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Echinodermata! Starfish! Sea Urchins! Sea Cucumbers! Stone Lillies! Feather Stars! Blastozoans! Sea Daisies!Marine invertebrates found throughout the world's oceans with a rich and ancient fossil legacy. Their biology and evolution includes a wide range of crazy and wonderful things. Let me share those things with YOU!

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    Wednesday (today) was the last day of the Okeanos Explorer's Oceano Profundo expedition, exploring the deep-sea habitats off Puerto Rico in the tropical Atlantic. In the next few months, they will transit through the Panama canal and onto Hawaii! 

    Among the most commonly encountered of the animals they encountered were swimming sea cucumbers! I've written about swimming sea cucumbers here.  Most of the ones we saw were benthopelagic, which is to say that they live on the bottoms but swim when needed/desired. There's really only one that is truly pelagic... 

    Several different morphotypes (species?) were seen..

    1. This transparent one...
    Here it was as it was taking off...
                                 
                                 

    Is this the same as this one??

     Were those the same as these? An Enypniastes like species (possibly Amperima or Peniagone?)
    It left MANY nice traces!
    2. This "sea pig" like one.. Elpidiidae? 

    3. The following ones were all "Benthodytes-like"
    This like one had a clear body and with an highly convoluted gut! 

    This one was a solid purple...
    4. and there was this whitish purple beauty! 
    5. and finally there was this weird pink one we saw yesterday....

    This last week had SO MANY exciting observations, so maybe there will be some extra posts soon....

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    It is May 5, 2015 as I write this. Thanks to a recent question from my Twitter followers (thanks @MissMolaMola!) I got it in my head that this month and indeed TODAY would be a great day to address one of the great fundamental questions in the evolution of echinoderms 

    WHY DO Echinoderms have FIVE PART (pentameral) SYMMETRY???

    Adult echinoderms have one of the more unusual features among "higher" metazoans in that adults have a form of radial symmetry called 5 part or pentameral symmetry. So, not only is the body radiating from a central axis but it does so in increments of five. This is in stark contrast to most other animals which show bilateral symmetry: two sides with paired limbs on either side as well as a head with centralized sensory apparatus. 

    Most times, non-bilateral symmetry (radial and absence of symmetry) is associated with "lower" or simpler metazoans. Mainly sponges and cnidiarians (jellyfishes, corals, etc.). And indeed in much of the 19th Century echinoderms were considered as PART of this lower "grade"of animals called the Radiata (more here).  

    But subsequent data over the centuries, first from development and later from DNA has verified without a doubt that echinoderms have complex tissues, organs and are actually more closely related to chordates (e.g., humans, fishes, etc.) than they are to "simple" animals. ALL adult echinoderms display radial symmetry (although as we'll see there is some modification).

    So, therein begs the question: WHY go "back" to have a body type that is seen primarily in simpler animals??  and why five? 
    (and in science "why" means what is the evolutionary reason, there is no metaphysics at play..)

    The answer to this question is... elusive. But here are some facts. 

    1. Larval Forms are Bilateral
    thanks to Dr. Allison Gong for the pic
    This is a fundamental part of echinoderm biology and part of what classifies them among the more complex animals. 

    ALL living echinoderms have a larval stage which is bilateral. These bilateral forms settle onto the sea bottom (or wherever) and develop pentameral symmetry as adults. 

    This is an important part of understanding their evolution, since life modes observed at these early stages can sometimes be reflective of the early evolutionary stages of these animals. 

    In this case, it shows that it shares the same morphology as other complicated animals in that it has bilateral symmetry in the same way that worms, arthropods, mollusks, and other "complicated" animals do. 

    Thus, pentameral symmetry is a SECONDARY characteristic "on top of" the "basic" bilateral symmetry. It had to acquire this feature during its evolutionary development.  And so when we ask WHY do they have pentameral symmetry? We are also asking HOW/WHY did this unusual symmetry evolve in echinoderms??? Figuratively speaking, it adds an additional step to its evolution by appearing with this body form. What's the deal with that??

    2. Are all adult echinoderms purely pentameral? 
    You may suddenly realize "AHA! I GOT YOU!  SOME echinoderms show kind of BILATERAL SYMMETRY AS ADULTS!" Don't they???

    Um. Well, yes and no.

    Two notable exceptions: "irregular" urchins and sea cucumbers. Both are unusual in that most are detritivores or process sediment for food.  Therefore requiring movement in one direction.

                                 

















    Bilateral symmetry is associated with directed movement and so, its presence is often associated with organisms which show some kind of single-directed motion.

    I've written about "irregular" urchins here.. basically a bunch of skeletal modifications that are part of the morphology in sea urchins that live/feed on sediment...(again, motion in a single direction)

    What happens in "irregular urchins is that yet ANOTHER "symmetry" is overlain/"added" over the radial symmetry.. So, these animals go from bilateral (as larvae)
    and eventually develop bilateral symmetry IN ADDITION to pentameral symmetry...  This is called SECONDARY bilateral symmetry.
                                             
    Sea cucumbers  show bilateral symmetry (right and left sides) along their worm-like bodies. Presumably, again because they have a life mode which requires them to show directed movement in order to feed.

    But you can see this five-part symmetry along the longitudinal axis of the body.. down the mouth or looking up the anus! Here we have anal teeth nicely showing pentameral symmetry!! (what are anal teeth? go here to find out)
    So, all adult modern echinoderms show SOME kind of 5-part or pentameral symmetry. Even if it doesn't always look like it.

    BUT was that ALWAYS the case????

    3. Not all echinoderms were pentameral...
    I've mentioned in past blogs that the echinoderms of the Paleozoic were mostly NOTHING like they
    are today. 

    Some such as this helicoplacoid (which I wrote about here) were actually asymmetrical! 
    Others, such as this carpoid echinoderm laid on the bottom with one side...
    Belemnocystites wetherbyi by avancna on DeviantArt

    and indeed some of the fossils which have been proposed as among of the oldest known echinoderms (e.g. Tribrachidium) show three-part symmetry...
    So, based on fossils like these, much of the older traditional paleontology suggested that echinoderms were evolving from different "grades" of symmetry.. 3-part to 5-part, etc. 

    Modern approaches including  cladistics and more intensive scrutiny to characters were applied... and it turned out the "family tree" of echinoderm evolution was much more complicated than simply being different "grades" of symmetry....

    Here are some phylogenetic trees from Mooi (2001)-a review of fossil echinoderm phylogeny... which show just how complicated the relationships can be. And that the question of symmetry in Paleozoic forms can be quite complicated.

    Some of the oldest lineages look like they don't have pentameral symmetry but in some trees, asymmetry is an acquired characteristic. Something that evolves later rather than a feature of early echinoderms..


    One of the lesssons from paleontology though: symmetry in echinoderms might be part of a changing/evolving body form through time rather than some discrete, adaptive event.

    4. A crystalographic/developmental explanation? 
    from Nichols 1967
    Perhaps one of the most involved explanations of pentameral symmetry which was applied to LIVING echinoderms came from a series of papers outlined by echinoderm biologist Dave Nichols in the late 1960s. He followed up on an original notion by a previous worker who pursued crystallographic arguments:  
    The pentagon is the only regular polygon for which the number of sides equals the number of diagonals...In all echinoderms whose development has been studied, the first plates to form include those at the apex of the animal-that is, at the pole opposite to the mouth. These plates are required to produce a body with basically a circular cross-section, and in order to reduce the planes of potential weakness across them, the sutures between them must be as few and as short as possible. Only with a pentamerous arrangement are these requirements satisfied. from Nichols 1967, New Scientist 14, pg. 547 (italics mine). 
    So, basically during development, Nichols arguments that the arrangement as seen above in "b"the theoretical  development of these plates that this is essentially the strongest arrangement of these plates. Four or six plate arrangements (a or c) presents a clear breakage plane whereas the 5-plate arrangement does not.

    He goes on to apply this structural explanation to various living echinoderms, but unfortunately, even Nichols admits, that this idea was experimentally untestable.

    5. Some insight from Evo-Devo! 
    Some of the more intriguing clues into the "How did pentameral symmetry evolve?" are almost certainly going to be found from the field of "Evo-Devo", which is short for "Evolution & Development". A multidisciplinary field which integrates genetics and developmental biology. Which genes "turn on" or express certain characters??

    One paper by Arenas-Mena et al. (2000) from Andy Cameron's lab at the California Institute of Technology in Development  shows expression of the Hox cluster of genes in the purple sea urchin, Strongylocentrotus purpuratus.
    Basically, what this colorful digram shows is the gene represented by color and what part of the larval form is being "expressed" or developing in the larvae. So, there is easily a LONG description of how each gene triggers a different body cavity or other structure to be expressed or to be formed but long story short: These are all features "tracked" from a bilateral larvae which are observed in the pentameral body form.

    There has undoubtedly been more work on this topic, but honestly, this was about all I was going to gather in the time I had and its a VERY involved field!

    So, developmental perspectives give us SOME perspective into the process and its a start, but ultimately there remain a LOT of questions.
    1. Is pentameral symmetry evolutionarily adaptive?
    2. How is it relevant to the calcium carbonate skeleton? If at all? 
    3. Under what conditions does pentameral symmetry evolve from an ancestral form with bilateral symmetry?
    4. How would this shift/expression be observed in early echinoderms? Like crinoids? 
    5. Does the "5 part crystal stability" theory have any support?
    Another fundamental aspect of echinoderms we know practically NOTHING about! Understanding of these types of evolutionary changes has important ramifications for many fields.. ecology, paleontology, developmental biology and even astrobiology! 

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    Following the last Okeanos Explorer cruise to Puerto Rico, a got a bunch of questions from folks about what the heck was going on with the very odd looking spines of this cidaroid urchin: Cidaris blakei?

    Some Etymology:"Cidaris" the genus name for this species (and the other urchins in the group)? is Latin for a headdress or tiara for ancient Persian kings The species name "blakei" is named in honor of the USS Blake, which was the vessel on which the species was collected.

    Now, "normally" (which is to say in the majority of other ciadaroid urchins) the spines are pointy or blunt. Surfaces might be more smooth (as in Cidaris cidaris)

    or kind of textured like so...
    Cidaroid urchins are unusual in that their spines LACK skin on the surface. Remember that ALL echinoderms display their ENDOSKELETONS. What you are seeing (spines, armor, etc.) are NOT a shell or exoskeleton. All the surfaces are covered by skin (an epithelium)

    Because of this, cidaroid urchin spines are affected by the environment. So, epizoics and fouling faunas grow on them. Worm tubes, barnacles, etc. 
                               
    From one of my prior posts, these Antarctic urchins, called Austrocidaris, which actually can "seed" new areas with the animals that live on its spines.

    So, what is Cidaris blakei doing with those wide, fan-like spines? Their unusual shape doesn't necessarily seem to display any obvious function. Defense? Some bizarre hydrodynamic function? perhaps to more effectively encourage growth of epizoics on the spines??
    I also came upon this pic of C. blakei, which seems to grow a lot of critters on its spines...
    from this echinoderm Scratchpad
    MANY other cidaroid urchin species are known for having very unusual spine morphologies which I've shared with folks over the years. Here's a bunch for comparison

    Broadly speaking, cidaroids are the only urchins that have these pretty weird spine morphologies. For what reason? Are they related to the growth on the spines?? (increase in surface area?) Defense? Reproduction? 

    A curious bunch of animals. "About which, very little is known.."

    Another one from the recent Okeanos 2015 Puerto Rico dive, this one was home to two serpent stars (I think.. Asteroporpa annulata)..

    This one is called Chondrocidaris gigantea, a species from the Indo-Pacific, which was in the Paris collections...
    Another curious species with very heavily serrated spines...
    The above species seems to have a fairly heavy growth on their spines..
    Another species of Chondrocidaris, C. brevispina, pic by Arthur Anker
    Here's the mysterious Tylocidaris (formerly Psychocidaris) with these thickened "cortex" covering the spines... (see more here)

    Some Haeckelian art showing odd cidaroid spines..
    More strange treasures from the Paris Museum I've shown before.. BOTH of these urchins are different species in the genus Goniocidaris

    But again, its unclear what they use the spines for..

    Here's a second species with VERY different spine morphology

    and there's a bunch of Paleozoic urchins that are worth checking out...

    Starting next week: THREE WEEKS OF BLOGGING FROM CAPETOWN, SOUTH AFRICA!!


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  • 05/28/15--22:11: Moments from South Africa...
  •                            
    For the next 3 weeks I am visiting the marine invertebrate collections at the Iziko Museum in Cape Town, South Africa!   


    Things are keeping me busy.. so here are some moments that give you some ideas of life on the road!

    Spines and arm from the South African goniasterid, Calliaster acanthodes...
    The mountains surrounding Cape Town as the fog clears...

    The original catalog of the South African Museum invertebrate specimens! (mostly now databased)
    This nudibranch, described by Dr. Terry Gosliner, named for Nelson Mandela...
    This lovely walk through the Company Gardens outside the Iziko Museum...
    Similar to the New Zealanders and the Australians, it seems that Cape Town also loves its fresh, hot meat pies!
    More to come! 



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    Greetings to everyone from Cape Town where I've been for the last two weeks! One more left to go!

    Sorry if I've been a bit quiet and off Twitter. What have I been up to? What have I been learning?

    1. Identifying Starfish!
    image by @MarineBio_SAM
    So, it turns out that the South African Iziko Museum's invertebrate zoology collection is probably the largest one of all the collections of its kind in Africa. It includes a huge number of specimens from multiple places throughout the region. So, all major groups have been building up on their shelves.

    BUT sometimes, groups need the attention that a specialized scientist, such as myself can offer: in this case the taxonomic skills to identify the many shallow and deep-water species which occur in the very diverse and wonderful waters of South Africa and nearby locales in TWO different habitats: a cold-temperate water setting on the west and south coast AND a tropical water setting on the east coast. Its unusal.

    The last starfish/echinoderm expert to visit Cape Town was in the mid 1970s. Specimen collection has been proceeding at a semi-regularr ate for this entire time. And so, there's a LOT of them.

    These represent valuable specimens with applications to everything from ecology to natural resource management.

    I've identified HUNDREDS of specimens.. some rare. some new. More on this to follow.

    2. Learning about South African Starfish!
    So, along with what I've been learning from specimens, I've also been in contact with an extensive network of South Africa's marine biologists, citizen scientists, and other ocean-themed folks who are likely to know about echinoderms in the region.

    I've been able to experience everything from pictures of living animals to general tips about local species. And yeah.. stuff that will hopefully find its way into a published paper...


    3. Observing that temperate water South African marine habitats look astonishingly like those from central California!!

    Thanks to some time at the Two Oceans aquarium and talking to colleagues, I have been reminded how stunningly similar (identical) the kelp forests of temperate South Africa can be!

    Most folks think of Africa as a tropical locale but I can tell you (especially since I'm here during their winter) that Cape Town gives Monterey, California a run for its money for kelp, urchins, rain and food!
    A kelp forest (Macrocystis) off Cape Town

    versus a kelp forest (Macrocystis) in Monterey, California

    These urchins are Parechinus angulosus (Parechinidae)

    these are the  purple  and red California urchins Strongylocentrotus purpuratus and Mesocentrotus franciscanus (Strongylocentrotidae) 
    In the case of the sea urchins, they're ENTIRELY different species in different families but they do appear to show some ecological similarities...

    4. Giving workshops & presentations on Starfish & more! 
    OUTREACH! By now, its probably clear that I am not one to shy away from sharing what I know about echinoderms with everyone.  Part of the plan for my visit to Cape Town was to share what I knew with students and colleagues.

    So, far I've given a workshop on the classification and taxonomy of starfish as well as a talk on deep-sea biodiversity at the Two Ocean Aquarium!  One more talk at the University of Cape Town next week!


    Have been LOVING talking to local citizen scientists, students and the MANY interested natural history enthusiasts in the area!

    5. Encountering familiar names & history far from home....
    So, even though I'm on another continent, there are a lot familiar names and a lot of shared history with my other friends and colleagues who have worked in South Africa-especially at the Iziko Museum!

    These two specimens for example show collected specimens and work by several of my colleagues. Gary Williams is curator of cnidarians at the California Academy of Sciences. Terry Gosliner, is the curator of mollusks/nudibrancs at the same institution. Angel Valdes is another colleague who works on nudibranchs...

    Its interesting how much of what I encounter here is part of this greater shared legacy in Invertebrate Zoology.
























    Another unexpected finding was this specimen, apparently identified by Smithsonian echinoderm worker and friend, Cynthia Ahearn who passed away many years ago. She often identified specimens for colleagues. This one was from 2002, in her distinctive writing and on a Smithsonian identification tag...












    More Next Week!

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    So, this is my last 2015 report from Cape Town and its been a GREAT three weeks. I've been working on the collections at the Iziko Museum courtesy of my colleagues at the South African Environmental Observation Network (SAEON).

     Lots of great specimens to study and good interaction with the marine scientific community in the South African region! An extremely productive trip.

    Plus, of course, first hand exposure to ecosystems and their faunas! I still marvel at the resemblance between the kelp forests & fauna here and in California!
    But here are some lasting impressions that I take away from South Africa that encapsulate the lessons learned over the last few weeks...

    1. One of the BEST collections of echinoderms in Africa is at the Iziko Museum! 
    This is always kind of a cheat of course. I just spent 3 weeks identifying a massive collection of sea stars, so OF COURSE, I'm a little biased!

    But seriously, the collections here contain historical materials from famous echinoderm workers like Hubert Lyman Clark and Ailsa Clark (unrelated). They've maintained a good record of marine biodiversity throughout the region for decades from intertidal to relatively deep-depths.

    The Iziko is undergoing many efforts to share its materials with the scientific community including digitzation initiatives and of course a collections database is ongoing!

    This is a great place to start your studies on the Indian Ocean or to survey the unusual temperate water habitats of South Africa!


    2. Citizen Science is thriving in South Africa!
    Perhaps one of the best things I've discovered about the scientific community in the Cape Town and South African is the presence of a very active diving community which LOVES to share and study the marine habitats they observe!

    Groups such as iSpotnature.org, SURG (the Southern Underwater Research Group), and even websites such as Eastern Cape SCUBA diving  show a multitude of pictures. This also includes the many pictures off Flickr and other photobanks.. I'm sure there are probably more...


    3. There are MANY wonderful ecological and natural history stories in South Africa but they are poorly studied.
    Probably one of the great things I learned about studying the fauna is how many cool things are out there and widely known to the local community but were not actually published! 

    For example, this amazing sea star, Pteraster capensis has been reported from throughout the area to brood and generate mucus! But was this an actual observation/report? Or simply an extrapolation from the scientific literature on the North Atlantic/North Pacific species? No scientific reports on this species are available (other than those that report taxonomy).

    But I finally spoke to George Branch and Charlie Griffiths at the University of Cape Town who verified that YES indeed. This has been seen!!  So, it will probably make someone a great paper some day!


    4. A HUGE diversity of sea stars exists in the region! (and now there is a reference collection!)
    As a follow up to the point #3 above, is the simple fact that there is a HUGE diversity of sea stars and other invertebrates on the shores of South Africa. You not only have those animals in the temperate water zones on the west and south coats BUT also the amazing Indian Ocean tropical species on the EAST coast!! Plus the deep-sea!!

    I've seen this species for example, identified as "Halityle regularis" in some field guides, but its a different color and is much flatter. Possibly a new record? Or merely a color morph of Halityle? We need to see more than a picture to be sure. I've alluded to possible undiscovered species in past posts... 

    BUT thanks to my work at Iziko identifying about 600-700 specimens we know have a bunch of baseline referneces for the fauna of South Africa!  But we will almost always have more pictures than specimens..
    5. The staff at the Iziko is AWESOME.
    I wanted to thank my hosts at the Museum who helped me with sorting specimens and managing data and other logistics. This includes Candice, Liz, Kanye and of course the curator, Wayne Florence

    P.S. The FOOD in Cape Town is AMAZING!

    I could NOT have predicted that OSTRICH tastes like very tender beef! Wonderful Grilled or "spicy Mongolian style"!!
    Also.. South Africans love cider and meat pies. EVERYWHERE!

    THANK YOU CAPE TOWN! I hope to be back!! 




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    Asteroidia | Asterinidae | Patiriella calcar [Variegated Sea Star] - Flat Rock, Ballina, NSW
    A lot of times on the blog, I talk about weird and often unfamiliar groups of echinoderms. But today I thought I would talk a little bit about a family of sea stars, the Asterinidae, which its most likely that most people have seen at some point. They're familiar and as a result, we know quite a lot about some of them..

    Members of the Asterinidae include some 150 species in over 25 genera spread out all across the world. Everywhere from the deep-sea to under rocks in the tropical Atlantic and Pacific. Most have five rays, whereas others, such as Meridiastra calcar from Australia can have up to 8 or 9..
    Meridiastra calcar #1, Blackmans Bay
    The many species go by several familiar common names: Bat star, cushion star, Knitted star..

    This is actually a good place to identify the very distinctive patterns in asterinids.. namely, these crescent or "knitted" looking plate patterns on the body surface..
    Asterina miniata, Bat Star, Dorsal Surface
                   Starphish Asterina (patiria pectinifera) Japan sea, Far East, Primorsky Krai, Russian Federation
    In fact, the Japanese word for sea star.. hitode, which means palm, may actually be BASED on an asterinid (Patiria pectinifera).

    But for once, there's quite a lot known about them! So here's five subjectively interesting facts about them!
    1. They live everywhere
    Asterinids occur all over the world with many in shallow water habitats, including under rocks in places as diverse as the North Atlantic. They often live under rocks, or hidden away in cryptic habitats..

    There is a HUGE diversity of these tiny little guys. Some are able to reproduce asexually but others just seem to get around.. Being small and easily transported...
    serennig - Asterina gibbosa - cushion star
    to tropical habitats in Singapore...
    Crown sea star (Aquilonastra coronata)
    This Callopatiria granifera was a species I observed in Cape Town South Africa!

    But honestly, one of the places you are MOST likely to encounter them is here.. in a tropical reef aquarium. These tiny ones are most likely in the genus Meridiastra or Aquilonastra.

    Again, this is one of those species which is small and easily transported.. Living rock is a GREAT place for them to turn up..

    This aquarium species is asexual and once one gets into your aquarium, you're most likely going to have a bunch of them after too long...

    So, you can encounter shallow water asterinids almost all over the world! Australia, South Africa, South America, Antarctica, North America, etc, etc.

    But as with most starfish groups, there are often weird deep-sea members... Both of these get to be pretty big sized animals.

    I've mentioned these briefly before.. the flat one on the left is called Anseropoda, which is SO flat that it feels like a cloth rag when you pick it up!  We know very little about it.. Sometimes, small ones are so thin that light shines through them! Its name literally means Ansero for "goose" and "poda" for foot.. So, Goosefoot starfish! These can get to be almost 1.5 feet across!

    The one on the right, is called Tremaster mirabilis. Katie Gale and her colleagues found that these will feed on coral in the North Atlantic. As a species it occurs widely around the world including the North Atlantic, the South Pacific and near Antarctica.



     2. Funky Feeding
    Asterinids practically EMBODY the classic feeding mode of stomach eversion in sea stars! Here's a classic video I've been showing since the blog started!  It shows the stomach extended out onto the glass and feeding on the algae and other good stuff.  Most other asterindis feed in a similar fashion...

    Sea star stomach (Bat star)

    BUT some are neat ambush predators!! One species in New Zealand.. Stegnaster inflatus pretends to be a cave and can actually AMBUSH tiny swimming crustaceans!!

    One of these days, somebody needs to actually make a video of this thing feeding!
    This image from SeaFriends in New Zealand













    3. Reproduction! Lots of it!  Asterinids are one of the most heavily studied sea stars because of their many reproductive strategies...

    Some, such as this "Asterina panceri"(Asterina gibbosa) actually BROOD their young
    Asterina pancerii birth
    From Byrne 1996, Fig. 4h

    and I've reported in the past on this other brooding species, which live inside their mother and whose babies will actually EAT one ANOTHER! 











    And of course when all else fails, there's always dividing yourself!  Asexual or fissiparous reproduction is why those tiny aquarium stars are so numerous! 
    asterina6361_281111
    IMG_3451

    3.  Commensal Worms! In the Pacific Northwest species, Patiria miniata, its been know for quite some time that there's actually a species of polychaete worm (Ophiodromus pugettensis) that actually lives on the underside!!
    Ophiodromus pugettensis

    This is one of the better studied species of asterinids, but there's many other species of Patiria and other species such as Patiriella and Meridiastra which have a similar surface morphology and are conceivably "habitats" for other animals...

    4. They are important to the Evolution of Sea Stars!

    Here's figure 2 from our paper...
    Yeah, I know the image is hard to read, but basically, what I wanted to show was how the Asterinidae seems to show close relations with several other groups of sea stars, including the big multi-armed predators, the Solasteridae
    Solaster endeca
    and the enigmatic Antarctic Perknaster.. 

    Also, the aforementioned Tremaster mirabilis? Sea stars which resemble this species can be found from the Jurassic!  And its position in the tree seems to suggest it might be... interesting..

    and of course, there's more I haven't summarized here.. their phylogentic history relative to their various interesting features, etc.. but that's another post!

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    Polychaete worm
    This week I celebrate International Polychaete Day which falls on July 1, the birthday of noted polychaete expert Kristian Fauchald, recently of the Smithsonian's NMNH, who passed away in April of this year (2015).
















    What are polychaete worms? 
    Polychaetes are segmented worms, which are distinguished by their leg like structures called parapodia, which each bear distinct bristles (hair-like structures) known as chaetae which are composed of chitin (the material found in arthropod skeletons).
    Alitta virens puziko 2
    In the traditional sense, polychaetes are usually classified with earthworms and leeches.  But more recent molecular phylogenetic studies have shown that the "Polychaeta"is actually a big messy group that likely includes groups of worms which, at one time might actually have been classified as separate phyla !
    This includes spoon worms (echiurans)
    Eastern Pacific echiurans or spoon worms
    and peanut worms (sipunculans)
    Phasocolosoma agassizii, Agassizi's Peanut Worm
    How many are there and where do they live? 
    Its thought that there are likely over 13,000 species of polychaetes which live in every ocean and at every depth (intertidal to >7000 m abyssal depths) and indeed a small proportion of them (about 168 species) even live in freshwater. The diversity of polychaetes is stunning. Those 13,000 species reside within 80 families!!

    As I've shown in photo essays here (by Arthur Anker), they can be STUNNINGLY beautiful!

    and some, such as these forms from Antarctica can be quite huge.

    Feeding ranges from deposit feeding on sediment, filter feeding to of course, raptorial predation which has been made famous by the Indo-Pacific Bobbit Worm! (Eunice sp. )
    Rise of the bobbitworm! (Eunice aphroditois)
    So, here's five subjective things about polychaetes for IPD!!!

    1.  Eat the Palolo Worm! Out in Guam and the Solomon Islands, there are several island cultures who are privileged to be around swimming polychaetes during their reproductive periods, where they undergo a stage/morphological transformation known as epitoky.
    The worms swim up into the water column en masse as seen here..
                                
    These worms are then promptly eaten by the locals. There are many accounts of this, such as here on National Geographic Palolo worm is considered quite the delicacy and is apparently very reminiscent of caviar and is served here on toast. A traditional presentation.
    From MrLavalava's blog!
    2. Polychaetes that glow in the dark! 
                                
    What would any group of invertebrates be without at least a FEW members that glow in the dark??? (i.e., emit bioluminescence?)

    I actually found two: this one is the "Bahamas Glow Worm"aka Odontosyllis enopla. This species looks like a more conventional polychaete

    And then you also have the pelagic (aka swimming) polychaete, Tomopteris! which is a bit more unusual given its habitat (the water column)
    Image from Wikipedia! 
    3. They have a fossil record dating back to the Cambrian
    All of the major invertebrate groups can usually be traced back to the very earliest moments in Earth's history when the first evidence of life appears. Polychaetes are no exception.

    This pic shows what is thought to be a Cambrian polychaete from the famous Burgess Shale in Canada. It is  appropriately enough called Canadia spinosa
    From the Smithsonian's Paleobiology-Cambrian Page! 
    The Royal Ontario Museum has a fairly detailed page on this animal here including some nifty paleo art showing what the animal might have looked like alive..
    There were apparently a few of these Cambrian polychaetes, including Burgessochaeta,  Phragmochaeta and others..  These were thought to have paddles and interpreted as having the ability to swim. Length: 2-4 cm, so some tiny beasts. 


    4. Many polychaete species live in close relationships with other animals
    The most photogenic polychaetes might be large predatory ones or possibly even the colorful Christmas tree worms..but there are many polychaetes with a cryptic lifestyle which includes living as a "guest" on other, larger animals.

    Sometimes with strong relationships than had been surmised. I wrote about the scale worm Arctonoe vittata a few years ago.  These worms live within the tube foot groove and along the underside of the leather star, Dermasterias imbricata on the Pacific North West coast. 

    In experiments, not only did the worms move to the sea stars when separated, but the seastars moved toward the worms! 
    Photo by Paul Norwood-from iNaturalist
    Scale worms are very dedicated commensals to their hosts.. As I reported from my time in Japan, these stayed with their host, a solasterid until death...





    Polychaete worms sometimes have highly specialized relationships. Here are a group of worms known as myzostomes, which are parasites on crinoids. and apparently have been parasitic on crinoids since the Jurassic! (Here
    Myzostome 1
    5. Many polychaete names are derived from greek mythology: nereids (nymphs) and goddesses!
    A comparison of the names of various nereids (sea nymphs or female water spirits) shows that there are in fact a LOT of them shared by a host of polychaete worms..
    "Nereid on Ketos" from "Pausilypon" in Naples - beginning 1st century AD - Naples Archaeological Museum - "Augustus and Campania" - Exhibition at Archaeological Museum of Naples, until May 4, 2015
    Everything from the genus for the "Bobbit Worm"Eunice sp.
    Jack in the box Bobbit Worm
    to Nereis which is itself, the Greek word for the water god Nereus
    The Worm
    Amphitrite, Goddess of the Seas...
    Amphitrite
    and her terebellid namesake..
    DSC_8341
    While I'm not privy to the original etymology of these names, its not unusual for the original scientists to name organisms which they perceived as beautiful with namesakes which befitted them...

    Happy International Polychaete Day! 

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    This image by Nick Hobgood via Wikipedia
    Last week, I had a pretty fun conversation with some colleagues, namely Anna and Ned deLoach at Blennywatcher.com, about benthic comb jellies and Its been awhile since I've had a chance to play "lets run through Flickr and see if we can discover anything new", so I thought I'd try my luck this week again !!

    What are benthic ctenophores (aka benthic comb jellies)? I've explained them before in one of my earlier posts (here), but simply put, they are an unusual group of comb jellies, which you might be more familiar with as purely pelagic or swimming animals, such as this "sea gooseberry"

    They swim with the shimmering paddles you see in the video and feed using those long tentacles as they are dragged through the water behind it...

    Benthic ctenophores (aka bottom-living comb jellies, benthic comb jellies, sessile comb jellies) are basically the same idea except that the animals live on bottom substrates. They occur in tropical habitats and in shallow to deep-water settings.

    Here's a nice pic of a species which lives on coral (image by Ria Tan and my friends over at Wild Singapore). You can see the tentacles doing the same thing..but oriented "upwards" away from the bottom.. and into the current.
                    Ctenophore (Coeloplana sp.)
    In the last few years with the proliferation of video and underwater cameras, we've been seeing more and more of them. And so, learning more and MORE about them!!

    Anna and Ned over at Blennywatcher.com for example were very lucky in that they were able to capture one such animal FEEDING for the first time ever!! (Here

     One of the main reasons, I got so interested in benthic ctenophores was that they live primarily on a starfish, Echinaster luzonicus, a 6-7 rayed species frequently encountered throughout the Indo-Pacific.

    The ctenophore species is presumably Coeloplana astricola (no specimens examined, so hence my caution). As you can see in the picture above.. the feeding tentacles project up into the water to feed as they do in other species..
                      AMBO200902270045
    Based on this cool video made by blennywatcher.com, there appear to be different species of benthic ctenophores present on each individual host. But usually not more than one species per host...

    Other hosts? Interestingly, a review of images on Flickr reveals at least ONE other sea star that serves as a host for Coeloplana.., Another species in the SAME genus as E. luzonicus.

    This one is called Echinaster callosus. A weird but colorful starfish with big puffy protrusions on its body surface...
    DSC_0907_DXOalex-2
    Here is one of the benthic ctenophores of the surface with its feeding tentacles extended...
    Coeloplana astericola

    Are these new records of hosts? I couldn't find these in my brief review of the literature, but I'm not a benthic ctenophore expert....

    How Far Can they GO?  Another question we always ask when we see stuff like this, is just how MANY of these ctenophores can "pile on" to a host starfish??

    This looks like a LOT. At least 20 to 30!! Nearly covering the surface of the starfish..
    Starfish, Seraya
    One with 20-30...
    Echinaster luzonicus  sea star with sessile ctenaphores ind11-3 06278
    Another one mobbed by benthic ctenophores! 
    Comb Jelly Attack
    and GREAT scott! this one is almost completely covered by them. By my count? About 40 to 60 of them.. but the outlines of each ctenophore are hard to make out...
    Starfish
    and more..and MORE! 
    Echinaster luzonicus
    Here's one with 4 arms being regrown also completely MOBBED by these ctneophores.. covering the surface
    Starfish comb jellyfish Coeloplana astericola
    Some individuals of E. luzonicus end up being practically a hotel for commensals! This one not only has the benthic ctenophores but some polychaete worms as well...
    Starfish comb jellyfish Coeloplana astericola

    Getting away from the benthic ctenos that live on sea stars, there's also been some cool observations of some others from Flickr and Twitter..

    Here's an unidentified Indonesian benthic ctenophore with its feeding tentacles out.. and maybe its caught something (a shrimp)? or perhaps its just the confluence of feeding tentacles..
    hunting
    From my colleagues in South Africa are a bunch of images via Twitter of something similar to Lyrocteis, a larger "bunny eared" benthic ctenophore from about 100 m off the coast of Natal...

    Some of these are just unearthly..
    and finally, from my friends at the California Academy of Sciences (Steinhart Aquarium) the curator of the "living collection" Bart Shepherd tweeted these 

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    Image from the Census of Marine life
    This week a new paper that I think everyone will be interested in! Remember back in 2012 when filmmaker James Cameron (famous for Terminator 2, Titanic, and Avatar) personally travelled down to the deepest known place on earth (> 10,000 meters!)?

    It was in all the papers! There was certainly some good criticism of what was accomplished but many argued that even though Cameron himself did not bring back very much, he did apparently make some collections which were studied by scientists at Scripps Institute of Oceanography in San Diego, California, and as explained by Deep Sea News' Holly Bik even mud from that depth holds the potential for interesting data (here). 

    So, here we are now THREE years later and one of the first papers detailing results from Cameron's Expedition has been published!! !

    The OPEN ACCESS paper was published just recently in Deep Sea Research in the May 2015 issue, written by Natalya Gallo at Scripps Institution of Oceanography and a host of coauthors, including yes, director James Cameron. 

    Cameron famously descended in the one-man submersible, DeepSea Challenger to 10,000 meters where he took some video and grabbed some mud..
    I saw him and his team as they stopped in DC on their way up to deposit the sub at Woods Hole Oceanographic awhile back...


    This paper by Gallo et al. details not just his dive but ALL of the dives undertaken by the sub during the expedition to the region, including several of the world's deepest trenches, including the New Britain and the Mariana Trench (Challenger Deep).  This totaled seven dives, five general dives and two into the trenches, overall ranging from 884 to 10,908 meters!
    Figure 1 from Gallo et al. 2015
    Everything was captured on video and these observations are scrutinzed and analyzed!

     What do they report??

    1. Organic input was different in the New Britain Trench
    In the paper, there is what they call "allochthonous organic input" which is"science speak" for organic external or foreign materials that fall into the deep-sea which was seen more heavily near the New Britain Trench than the other regions sampled.
    Figure 4 from Gallo et al. 
    In this case: plants and other related material: palm fronds, leaves, sticks, etc. but also carrion or dead animals..  Many of the animals observed interacted with the plant material.. some living on or hiding under..

    In contrast, the carrion in the form of bones, etc. contributed food or nutrients to the ecosystem..

    I am always keen to remind folks how important what happens at the surface impacts what happens at the deepest depths. Note here at 1000 meters food still falls FROM THE SURFACE.

    2. Deep-sea Starfish?
    One of the more interesting finds was the observation of these starfish living on bones and woody debris at 8.2 kilometers down! (8200 meters!!)

    These were identified as caymanostellids, a weird group of deep-sea starfish which live on wood. No scale was available but known examples of these sea stars are relatively small.

    If these are truly from 8.2 kilometer depths, they might be the deepest individuals known for this group! WOO!
    I've mentioned the deepest known records of OTHER starfish species here. Some of the deepest records are recorded from 8400 meters! So 8200 meters isn't much of a reach. 

    3. Lower abundance & diversity in nutrient poor canyons
    Figure 7 from Gallo et al. 

    This is the "on the other hand" of the study areas. The New Britain Trench (NBT) at 1000 m was nutrient rich but the Mariana Trench at the nearby Ulithi Atoll region (1100 m) were relatively poor in nutrients.

    Correspondingly, the abundance AND diversity of animals observed was much less in the Mariana Trench and Ulithi Atoll regions.

    The New Britain Trench site also seemed to demonstrate MORE diversity than the other two studied regions.












    4. There is a large and diverse bottom/scavenging community in the New Britain Trench.
     
    Figure 10 from Gallo et al. 2015
    The New Britain Trench (NBT) seems to be showing a huge diversity relative to the Mariana Trench and this was further seen int terms of scavenging communities such as the amphipods.

    Looking at the number of amphipods in each video (per frame) they observed that there was a HUGE difference in the number observed!

    Those in the New Britain Trench were MUCH more abundant!

    Multiple species were likely present but this assemblage also apparently included the "supergiant" amphipod Alicella gigantea:
    Image from the BBC
    Sea cucumbers and various crustaceans were also apparently present...

    One interesting thing: Absent from ALL the deep localites on this dive?  NO FISH were observed. Its been argued that fish "bottom out" at about 8000 meters and are unable to occur below that.. The observations here seem to be consistent with this data.

    5.  Other animal observations.. Potentially new species?? 
    Among the few animals observed at depth (from their Figure 9 below) were an odd ulmariid jellyfish (labelled C) as well many other crustaceans (D) which were either mysids or some kind of shrimp like crustacean..
    One of the significant discoveries was this "squid worm", a swimming polychaete, likely in the genus Teuthidodrilus from 1 KM down in the New Britain Trench!!  These were originally described from the Philippines. 

    5a. The Deepest Known Deuterosotome Known Probably one of the DEEPEST of the critters noted in Gallo et al's paper were, you guessed it! SEA CUCUMBERS.

    In the Marianas trench at the deepest depth (10,900 meters!) they observed sea cucumbers oriented into the current, which is consistent with behavior seen in deep-sea sea cucumbers like sea pigs  

    The animals observed from the deepest point were only tentatively identified as members of the family Elpidiidae (Fig. 10 on the right G & H). They indicate these might possibly have been Peniagone sp.  (Note Peniagone below is only for representative purposes and was NOT from Gallo et al.'s paper!)
    Peniagone islandica from EOL

    Previously, the deepest known sea cucumber was Myriotrochus brunni which was collected from 10,710 meters in the Mariana Trench.

    However, the account by Gallo et al. for the elpidiid sea cucumbers (their Fig. 10, G, H) are from 10,900 meters!! Which yes, makes them the DEEPEST known deuterostome animal!!  (and certainly the deepest known echinoderm!!)

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    Image by Arthur Anker
    AMPHIPODS! What are they? Small, very diverse crustaceans that occur all over the world in marine, freshwater and even terrestrial habitats. They are distinctive in that their bodies are laterally compressed, in other words, their bodies are "taller" than they are wide.

    There's a bewildering diversity of them with over 9500 species known.
    Most of them are pretty tiny (about 1.0 to 20 millimeters) but some giants approach 34 centimeters (13 inches!).. such as these supergiant amphipods which live in the abyss of the deep-sea at 7,012 meters!

    There's a MASSIVE amount of diversity within the group. Some are transparent, while others are colorful. Sometimes they occur in huge densities and are often thought of as the "bugs" of the sea. They often act as detritivores/scavengers as well as predators..

    I thought today might be a good idea to share some of the more unusual body forms, courtesy of the highly talented photo naturalists on Flickr. Enjoy!

    Epimeria loricata by Olga Zimina

    Apparently 2 different color morphs of Paramphithoe hystrix by Olga Zimina
    A "Jewel beetle" amphipod by Arthur Anker

    A stunning podocerid? from Arthur Anker
    A stunning hyperiid...


    Some interesting "reef aquarium" species by Waldo Nell
    the same under green filters/light!

    Some Antarctic amphipod goodness (Echiniphimedia hodgsoni ,family Iphimediidae-ID by Marie Verhaye!) from US Antarctic Research Program at the NMNH

    and a delightful species from the White sea.. by Alexander Semenov

    There's this stunning beauty, ..also by A. Semenov


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    Following International Polychaete Day (July 1, here),  I found there was quite a bit of neat stuff worth sharing, which led to more and some more.. and so a second polychaete post in July! woo!

    So, many of the polychaete worms have some pretty impressive jaws! Many are raptorial predators such as everyone's favorite eunicid-the Bobbit worm But many are just as easily omnivores or scavengers. 
    Rise of the bobbitworm! (Eunice aphroditois)
    Honestly, I'm not sure which species are known for specific habits. As we'll see even having an eversible pharynx does not seem to be immediately associated with predation. Although the "fast strike"/raptorial approach seems likely.. 

    Here's a nice one with 4 jaws! Pharynx of Lepidonotus squamatus, which is a scale worm (Family Polynoidae)
    It can beat you!
    Here is an SEM of another scale worm, but from a hydrothermal vent habitat..
    Hydrothermal worm
    Not sure which kind of polychaete this is from, but I'm going to guess that its from something similar to the above scale worms..
    I'm hungry!!!

    And of course, the giant Antarctic Eulagisca gigantea, which I briefly featured here. Honestly, I'm not sure its positively known whether this is predatory or not, but it sure does seem to be...

    So, here: let's look at some other polychaete worms that seem to have the apparatus for predation!The eversible pharynx for example, seems to be used for grabbing hapless worm food! Lets take a look at a nice video of one in this green paddleworm,  Phyllodoce lamelligera

    Here's a pretty incredible video showing the green worm with an INCREDIBLY extended proboscis trying to devour the red polychaete next to it.. Yow.


    These two both identify the subjects as Glycera, which I'm not 100% sure of, but it does look like they both show off that impressive polychaete proboscis!


    Here is the extended proboscis of a swimming (pelagic) alciopid worm, which uses its proboscis in the same fashion, to catch itself some dinner...
    Vanadis

    Here is a nice phyllodocid worm with its proboscis extended..
    The little monster
    And here's a very formidible looking one from Nephtys sp. 
    Dangerous
    Another extended proboscis in a nereid worm from French Polynesia..
    Jaws
    and of course.. the Bobbit worm, Eunice sp. with its big spring loaded jaws!!  Some of these Bobbit Worm macro shots are so tight, its practically like one staring you in the face!

    By now, I'm sure EVERYONE has seen Bobbit Worm predation. But if not, and you want to learn more about Bobbit worm taxonomy, Go here
    Face to face (Eunice aphroditois)

    Bobbit Worm
    ON the other hand, here is an eversible proboscis in a lugworm, Arenicola proboscis, which is a deposit feeder


    and to cover the full gamut, this video shows the proboscis in what looks to be some scavenging. I do not vouch for the identifications..


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    NOAA Ocean Explorer: NOAA Ship Okeanos Explorer: Galapagos Rift Exploration 2011 - EX1103 Leg2

    At the moment, the Explorer has been mapping the region and you can see all ofthis live, but come Saturday you'll be able to watch the actual EXPLORATION of the Hawaiian deep-sea here:
    NOAA Ship Okeanos Explorer (R 337)
                                 
    Why am I so Farkin' excited about this??
    I've been studying deep-sea Hawaiian starfish since the mid 1990s and in fact, my very first EVER publication was a checklist of Hawaiian starfish based on material at the Bishop Museum in Honolulu. In 2001 I got to actually go to the BOTTOM of the Hawaiian deeps! (about 1000 m I think?) in the submersible Pisces V

    So, to actually be able to SEE all of these species with High-Definition video?? EXCITING!!

    What Sorts of Starfish and other Echinoderms Will We See??
    As with past Okeanos Explorer dives, the dives will involve a Remotely Operated Vehicle deployed to the deep-sea with narration but also with ONSHORE support via phone, computer and social media. That includes me and a veritable ARMY of other marine biologists, including ecologists, taxonomists (i.e. people who identify different species) and geologists.

    I've helped summarize the various starfish species seen on Okeanos Explorer dives in the North Atlantic (here).  But the diversity in the Hawaiian region and especially in the Pacific is fair bit MORE diverse!
    and even though there's been a deep-sea research operation in Hawaii for the last 30 years or so, the truth is, we don't know a lot about many of the animals which live out here. So, the chances of our seeing something new out here? I would think those chances are VERY good!

    The folks at the Hawaiian Undersea Research Laboratory have an "ID Gallery" not just of Sea stars but of ALL the many different animals found at depth here... from crustaceans to corals and sea urchins to fish! 

    There's the potential to encounter one of approximately 55 species of deep-sea asteroids described in the Hawaiian region (that's not including any shallow water species).
    I've had the pleasure of describing at least four NEW species in the Hawaiian region, including  Apollonaster kelleyi, named for Dr. Chris Kelley who will be one of the science leads on the Okeanos team!
    We may even get to see my other new species, Astroceramus eldredgei (named for Lu Eldredge at the Bishop Museum) in glorious feeding action!
    Image courtesy of HURL
    Image courtesy of HURL
    Here are some posts I've written about the deep-sea Hawaiian fauna, including
    BUT WAIT! That's not all! What about the Citizen Science part I mentioned!!! 
    The Okeanos live stream has played a big role in part of a new and fascinating dynamic to deep-sea research!  Citizen Science!

    Now ANYONE around the world can watch a live streamed research cruise! (Note: Google is GREAT at helping calculate the time differences in different parts of the world).

    But how does the citizen science thing work?

    Screengrab software is pretty much a free feature on computers. My macintosh has it and I'm pretty sure most PCs have it. And if it doesn't already come with it, you can probably download some free software for it.  There are even software apps that allow you to take short movies off the video feed.

    So, basically, ANYONE can basically take a screengrab off the feed and contribute to a larger community of scientists and other interested people who are interested in deep-sea biology!!

    IF YOU SEE SOMETHING NEW you will see it along WITH the scientists and the entire world!
    Who knows? Maybe a screengrab that YOU take could lead to a new discovery!!

    Where do you find these and how do you contribute?

    There's TWITTER of course! Hashtag it with #Okeanos and Boom! there it goes!  If I can, I actually make it a point to LIVE TWEET any identifications and observations I make off the live stream..
    In addition to my Twitter handle: @echinoblog, others scientists and biologists who are usually watching include
    @ademopoulos An ecologist at the US Geological Survey
    @DrChrisKellogg A microbiologist/coral biologist
    @CarinaDSLR A marine biology PhD student 

    But there are often many, many more...

    The other interesting option is the FACEBOOK Underwater webcams Screenshot Group!  So, basically if you join, this group is made up of nearly 1000 people (some scientists but many are not) that are just taking and posting screengrabs from underwater live stream video including R/V Nautilus and Okeanos Explorer.

    There's usually someone on taking a grab of something almost 24 hours a day. If you missed that cute dumbo octopus?? Not to worry, in all liklihood, someone took a screen grab of it on this group!

    If you see something during the Okeanos feed, you can usually ask someone on Twitter or in the Facebook group and one can usually get a response the same day.. There are innumerable taxonomists and scientists monitoring. Some will call in on the phone, which you'll be able to hear on the live stream, others may add information via the Facebook group while others such as myself may Tweet an answer.

    New discoveries happen pretty regularly. New behavior. New species. Sometimes even rarely seen species!  On the last Okeanos Cruise, you may remember that they observed a deep-sea starfish which had not been seen since 1878 (130 years!)

    Who knows what we shall discover in Hawaii???


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    OKEANOS EXPLORER!! Since July 10th one of NOAA's primary research vessels has undertaken research in the Hawaiian Islands region, but it has only been since Sunday (August 2) that the Okeanos Explorer has begun live-streaming their video of the deep-sea (> 1000 m) bottom communities of the Hawaiian Islands. 


    A lot of their research in the area involves studying and characterizing the bottom communities-that is the organisms which make up the life living on the deep-sea bottoms.

    This includes a variety of colonial animals such as coral (actually a catchall term which includes different types of cnidarians such as sea fans, soft corals and antipatharians) and many, many different kinds of sponges!!
    Sponges are animals, and although they are considered among the simplest they are FAR from the simplest to understand. Sponges, as a general concept, occur in the family tree of life just before proper body tissue have developed but just after cells have come together to act together as part of a greater body. There's a huge variation in the body plan of sponges but most typically use some kind of inorganic material to form a supportive skeletal structure. 

    For example, one grouping: the Hexactinellida aka the "glass sponges" have skeletons which are made primarily out of lattices of silicon oxide, in other words.. glass. 

    Glass sponges are weird. In addition to their glass skeleton, which is demonstrated here in the shallow-water Euplectella
    Venus' Flower Basket (Euplectella aspergillum)
    Their skeleton is composed of the skeleton which is covered by an organic substance known as a syncytium. A syncytium operates at nearly a cellular level being composed of amoebocytes (i.e. independent cells) rather than formally developed tissue. 

    In spite of their relative simplicty, the skeletons are complex and there's a LOT of variation in hexactinellids. They live in shallow and deep water. Mostly deep. There are over 500 species ranging from relatively shallow habitats to deep-sea habitats in 2000 to 6000 meter depths!

    A LOT of these glass sponges are members of deep-sea habitats!  Here's a pic of the sea bottom at about 600 m or so? From off the island of Kona. These are ALL glass sponges. and each of those stalks anchoring them into the sediment?? Glass. Practically fiber optic cable! 
    The Okeanos Explorer has been seeing a LOT of these glass sponges! They form an extensive part of the deep-sea habitats in the Hawaiian Islands region.

    Some, such as this one called Regadrella has a more vase-like shape..
    BUT the opening (called an osculum) is covered with an intricate glass covering called a sieve plate..
    Others like this new genus/species is just kind of crazy looking. LOTS of weird textures and interesting folds attached to a stalk.
    Another one... but with a slightly different morphology I think..
    One thing to realize is the two red dots: These are 10 cm across.  That means this thing is HUGE!
                               
    Here was the dead broken stalk from another different species. A big one.

    For size comparison, here's the stalk versus the ROV. EASILY 2m long! (6 FEET!)

    This one gives you some idea of how the stalk looks on living glass sponges. These aren't the same as the one above..but general notion..

    If by the way you've always wondered what the texture of these stalks might be like? go pull some fiber topics out of your wall!Did you know that glass sponges are actually studied as inspiration for better fiber optics?? (here)

    Although most sponges are filter feeders, some of them, such as these inoccuous looking cladorhizid sponges are actually carnivorous!!  These are likely predators on other animals!  These were unknown in the Hawaiian Islands region and are a new record for this group!
    If you'd like to learn more about predatory sponges, my friends at MBARI have a TERRIFIC video about them

    Sponges are also interesting in that, although they are animals, they don't really move and often serve as habitat or perch for various OTHER animals...

    Numerous little crustacea, such as shrimp and copepods such as the ones shown below inhabit these large glass sponges for example..
    This feather star has seen fit to use this glass sponge, Farrea sp. as a perch for filter feeding
    and of course OPHIUROIDS!! You can't have a deep-sea sponge assemblage without brittle stars! (in this case.. ophiacanthids)
    What sorts of things will we see next week? WOO! 

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    Over the last few days, the R/V Okeanos Explorer has deployed its Remotely Operated Vehicle, the Deep Discoverer into some of the deepest waters in the Hawaiian Islands region, specifically in the Papahānaumokuākea Marine National Monument!  Many of the study areas have never been studied before.

    The Okeanos Explorer's primary objective here is to map and document the communites which form the habitat and primary fauna of this region. And so, a majority of their time goes towards studying the many, MANY deep-sea sponges and corals which make up these habitats. 

    The main page for the NOAA Hawaiian Expedition can be found here.

    Their LIVE feed can be found here.


    I've been tweeting the LIVE stream of the Okeanos' various discoveries and last week I documented the many, MANY different types of glass sponges seen by the Okeanos Explorer

    This week I thought I would just digest some of the various discoveries made which I thought warranted a place in today's post! Although most of the screengrabs here are mine, I am ETERNALLY grateful to the Facebook Underwater screengrab group! 

    1. Is this the world's LARGEST KNOWN SPONGE??? (Glass sponge or otherwise??)

    Here was a pic of the ROV Deep Discoverer NEXT to the sponge. it was approximately 3.5 m long X 2.5 m tall, that's about 11 feet x 8 feet LONG!
    Sponges and corals are known as "ecosystem engineers" because they play host to numerous other species and essentially become huge hubs of biodiversity. Many, MANY other animals live on these sponge colonies: brittle stars, starfish, squat lobsters, etc. the list goes on...


    SOMETIMES, the community is a little more permanent than others. Here's a shrimp which lives inside this "glass cage" sponge. This species mates and lives inside the sponge for the rest of its life...

    This story, of the "Venus flower basket" which is a pretty obvious deep-sea invertebrate "love story" is seen in the genus Euplectella. One can find more accounts of this story all over, such as here. 


    2. Starfish FEED on glass sponges!
    You wouldn't think there would be much on a glass sponge to eat, being composed primarily of... glass (see last week) but there IS that syncytium, the weird cytoplasm like stuff that covers the glass skeleton and a starfish has gotta eat.. 

    Some goniasterid that is not clearly identifiable..
    A "wolf pack" of Henricia sp. approaching on and feeding on this fallen glass sponge..

    3. There are multiple species of deep-sea starfish which feed on corals too! 
    One of my primary research interests and one of my favorite things to watch are deep-sea goniasterid starfish feeding on corals. I worked on these for my PhD and have described several new species of these animals (here) and here.  and even here

    In Hawaii, there are several species of coral-devouring sea stars. Many of them display a fairly prominent border of spines around their body...

    Calliaster pedicellaris
                              
    Evoplosoma, probably E. forcipifera
    and a new species I described last year, Hippasteria muscipula

    4. Special Weird Deep-Sea Treats! The Bottom-living or "dandelion" siphonophore!!
    A siphonophore is a gelatinous animal that is a sort of colonial jellyfish closely related to the Portuguese man-o-war. Siphonophores are best known as swimmers in the pelagic or open ocean. In the deep-sea, there are some species which live near the sea bottom and float above the surface, dragging their tentacles along the surface..
    If the weird beast above seems kinda familiar, you may have seen another species of this "dandelion" siphonophore in other news....such as this one from Africa which has been making the news rounds as a weird "spaghetti monster"

    The mystery of the million barnacle plates! The bottom was littered with millions of barnacle plates, but WHERE ARE THE BARNACLES??
     We did see a few, but were they even the same species??

    5. and my personal favorite..a sea urchin called Aspidodiadema hawaiiensis! A strange sea urchin that looks like the spider robot from Johnny Quest! I've mentioned these before in my post about HURL's deep-sea Hawaiian urchins
                           
    These seem to move around via a combination of their tube feet and these long bowed spines which seem to extend to the surface.
    Also of interest are the beak-like structures near the base. These are called pedicellariae and given how large and prominent they are, I would speculate that they are extended for defense. Perhaps to protect the tube feet??
    I also love these animals because they resemble the "robot spy" from Johnny Quest! 
    And yeah, post this week was a bit late. Laptop in the shop! More next week! 

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    the red stalked crinoid Proisocrinus ruberrimus
    So, sadly, the Okeanos Explorer's first leg has come to a close as it has concluded its survey of the 
    Papahānaumokuākea Marine National Monument and the ship has gone into port at Pearl Harbor to prepare for the third leg of the research expedition starting August 28th, surveying the main Hawaiian Islands and Geologists Seamount!! YOW!

    What sorts of COOL inverts did we see in the last 7 days?? Here are the ones that caught my eye...
    1. Benthic Ctenophores on Sponges Galore! 
    Many of you know that my blog showcases some of the most extraordinary examples of invertebrate diversity that I can find. I have talked before of my love of benthic comb jellies (aka ctenophores), which most people, if they experience them at all, encounter them in shallow water (here). 

    Long story short: these are similar to jellyfish, most are swimmers, but some are specialized to living on the sea bottom or other substrates.

    They occur in the deep-sea but are VERY poorly known there. Here are what are undoubtedly NEW observations. Possibly even a new species of these animals living on glass sponges between 1000-2000 meters!

    Here's a tight shot showing only a few with their tentacles extended. These tentacles were actually measured by the folks on the ROV. They can get to be OVER A METER (3 feet!) LONG!

    2. The Rare(ly encountered) starfish Pythonaster sp.!
    Exciting to me was the discovery of one of the "holy grail" of deep-sea starfishes: A species in the genus Pythonaster! NOT PREVIOUSLY KNOWN FROM HAWAII!  Or for that matter, this far in the Pacific!!

    We have seen a different species of Pythonaster in the Atlantic on previous Okeanos cruises (here), but those were known from older records. Not only were these new, but now we had pics of them FEEDING on a sponge!!    AMAZING!
    NOTHING has been known about the biology of Pythonaster. In one picture, we now have MORE information on its biology than we've known since this animals' description in 1885!!!

    Worldwide, there are less than maybe 10 specimens of this genus known!

    3. A bizarre community of deep-sea tunicates, barnacle plates and...????
    So, the last day the ROV from Okeanos Explorer was deployed they investigated a channel between west Nihoa and West Pac where the water current was quite strong.

    They encountered sponges (of course!) but curiously also a number of other bizarre members that formed an unusual deep-sea community.
    This community was made up of tunicates (Chordata-the same phylum to which humans belong!) aka sea squirts. These are filter feeders but not one of the usual species of tunicates one expects to find between 1000 and 2000 meters!!

    These are those brown potato shaped things in the picture above. Note how they are all clustered together in neat, almost ordered serial rows.

    Weird.
    Also observed were these odd little yellow blobs, which formed long, reticulating networks. It was unclear what these were. Maybe more tunicates?? sponges??  
    But they were ALL OVER the place!!  see all those long drippy yellow threads?? THOSE were all of those little yellow/gold blobs...

    One other part of the mysterious west Nihoa community (and indeed all over the place): The  mystery of the dead barnacle graveyard??

    Basically, it came down to the act that we were seeing these giant barnacle plates ALL OVER the bottom in HUGE abundance. Here's a close up, but you can see them above in the pictures.

    But WHERE WERE THEY?
    FINALLY the Okeanos Explorer team discovered them!! They were apparently giant deep-sea forms in the genus Chirona, But they were nowhere NEARLY as abundant as they were turning up in the barnacle "mounds". What happened?? Weird.

    4. PURPLE CRITTERS!
    Some animals in the deep sea are purple.

    A purple squat lobster. Not sure if they got a name to it.
    The stoloniferous octocoral Clavularia.
    The gorgonian Victogorgia sp.
    and this cute little jellyfish, which thanks to George Matsumoto at MBARI I know is called Crossota millsae!!

    5. Nice Shots of the Slime Star Hymenaster!  But which one? 
    I have written about the oh-so lovely and unusual members of the Pterasteridae before (here). And we see them in deep-sea habitats all over the world.

    But in the Indo-Pacific there is a HUGE expanse with MANY, many more species to be considered!

    Here is a species observed by Okeanos Explorer just a few days ago! The hole, which opens and closes is called an osculum.

    and thanks to Steve Hornik(@shornik ) this VIDEO!
    I've studied Hymenaster in Hawaii before. This one, from an expedition I was on in 2001, was identified as Hymenaster pentagonalis, described by Walter K. Fisher in 1905
    It emits a healthy defensive mucus!!
    So, what is this purple one???
    Or this ONE??  Deep Sea MYSTERIES!!???


    Many other cool critters seen-but I leave you with an assortment of weird glass sponges....
    What will the next leg of the Okeanos Expedition discover??


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    So, after a bit of a delay on Friday (the 18th) due to some technical issues, the Okeanos Explorer promptly got underway to begin LEG THREE of its Hawaiian Islands Expedition! Exploring Deep-Sea Coral Communities! (here

    Previous posts include: 




    Leg 3 has only been active for 4 days (including today) and already they've seen some pretty fantastic invertebrates!
    1. This awesome blue comb jelly.
    On Sunday (Aug 30th), the ROV was in relatively shallow water and spotted this gorgeous blue/purple comb jelly (ctenophore) at about 450 m off South Point, Hawaii (big island).  George Matsumoto of MBARI has described it as Euplokamis-like..

    Lasers below are 10.0 cm apart..so it was a decent sized beast...

    2. Was that a NEW STARFISH?
    So, this happened only Monday.. The ROV was exploring McCall Seamount at around 2700 meters and came upon this beast..

    So, the amazing thing about this is, I didn't recognize it! If you wanted to learn what it was like to "discover" new species along with the scientists??  THIS IS WHAT THAT IS LIKE.
    Unfortunately, they couldn't collect it for various reasons..but I'm hopeful an example will turn up so I can eventually confirm its status and learn more about it... and eventually give it a name...

    But as you can see its quite soft and its body sort of flutters in the current! 
    Video

    3. Coral Predators GALORE! 
    So, for years we've been watching sea stars and even sea urchins feed on deep-sea corals on the Atlantic Okeanos Explorer video streams. Earlier this year I published a paper on several of these starfish species, including Evoplosoma and Hippasteria.

    The Hawaiian islands region has many, MANY corallivorous starfish species. I've discussed a few of them here.  Its interesting to see how much more regularly we are observing predation by sea stars (mostly Hippasteria muscipula but several species are observed) on these octocoral colonies.

    What we're also seeing is predation on corals by cidaroid sea urchins!!  We've seen this by the white Atlantic urchin Echinus in the Atlantic, but observations of feeding on corals hasn't been seen by Okeanos in the Pacific before! 

    If indeed that is what they are doing in these pictures...

    4. Deep Sea crustaceans! 
    This deep-sea hermit crab has a commensal sea anemone instead of a shell! 
    Deep Sea balanoid barnacles! at 2700 meters! 


    5. More orange echinoderms than you can throw a stick at! 
    This cool biscuit star: Sphaeriodiscus ammophilus

    Based on a tip by ophiuroid expert Sabine Stohr, this ophiacanthid brittle star is likely Ophioplinthaca!
    and another nice shot of Hippasteria muscipula which I described only last year (here) What's interesting about it? the disk is HUGELY swollen with water!  A big difference from seeing them preserved in a bucket!!!

    What discoveries will next week's expeditions bring???


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    Image from page 459 of "Brehms Tierleben. Allgemeine kunde des Tierreichs" (1911)

    So, while we are waiting for the next leg of the Okeanos Explorer to begin this weekend, I thought it would be a good time to share some newly uploaded illustrations scanned from classic monographs by the Biodiversity Heritage Library and the Internet Archive Book Images Flickr site.

    Here are a couple of lovely color plates of echinoderms from the Great Barrier Reef from H.L. Clark's monograph on the Echinoderms of Torres Strait. 
    n95_w1150

    Some Astropecten..
    Plate 1

    And some coloriffic ophiuroids! 
    n666_w1150
    And here's some great Deep-sea Echinoderm Pics! 

    A bouquet of Isocrinid stalked crinoids! 
    Image from page 25 of "The royal natural history" (1893)

    and the living ones..

    Probably one of the COOLEST things I found was this deep-sea illustration from the Brockhaus Konversations-Lexikon, 1892. Some kind of natural history/science encyclopedia.

    It included many, MANY deep-sea animals we see today from Okeanos (and other) video. below I've presented images of these plates along with some images of comparable living species.
    Image from page 963 of "Brockhaus' Konversations-Lexikon" (1892)
    Note #12 above? That's the deep-sea sea cucumber Oneirophanta mutabilis.. Here's a pic from a recent Okeanos trip for comparison

    Image from page 962 of "Brockhaus' Konversations-Lexikon" (1892)

    Note #17 above? Thats supposed to be Hymenaster rex, a North Atlantic slime star. Here's an ACTUAL picture of one that is doesn't QUITE meet with the artist's concept...

    Here's the giant deep-sea sea spider Colossendeis in comparison with #20 above. 
    Sea spider


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    Okeanos Explorer has begun Leg 4 into the Northern Hawaiian Islands and their last stream on Sunday was chock full of amazing vistas full of deep-sea (about 400-500 m) sea pens and corals! 
    Probably one of the most exciting parts of these cruises is that I'm able to actually watch my favorite starfish species, some of which I described, in ACTION! Feeding on what turns out is their favorite food: octocorals!!


    Sea pens are big fleshy octocoral colonies that look sort of like an aquatic "quill" or pen. Here's one called Ptilosarcus, which occurs in shallow water from about SCUBA depth. 
    Sea Pens
    Octocorals are specific type of cnidarian, which have eight arms on each polyp. They have a whole diversity of body forms and can be more colonial, such as this gorgonian or more like a big fleshy stick like the sea pens seen above..

    The majority of the sea stars that we have observed feeding on octocorals are in the family Goniasteridae. As a generality, they look like this.
                                        
    A big peripheral ring of plates frames their body. They can be anything from completely pentagonal to more star shaped. Many are covered by spines whereas others are not..

    Among the best known of shallow-water goniasterid octocoral predators is the so called "spiny star" aka Hippasteria phrygiana (aka Hippasteria spinosa, etc.), which used to be known by MANY species before being recognized as one wide-spread species which occurs in three oceans! (here). 
    Spiny Red Star snacking on a Sea Pen

    This species occurs at SCUBA depth (and deeper) and many, involved studies have documented how these animals are important parts of ecosystems due to their predation on sea pens.

    Thus, it makes a lot of sense that several of the deeper water species of Hippasteria, such as this Hippasteria imperials seen by the Okeanos Explorer should be a fairly active predator on deep-sea sea pens! 

    Disks are swollen with water...
    Here is just a gorgeous shot showing a seemingly endless vista of sea pens with these two large, Hippasteria imperialis roaming around like they own the place! 

    BUT, Hippasteria imperialis isn't the only goniasterid starfish which feeds on octocorals. Many of its relatives, both close and far are also pretty active predators on deep-sea octocorals..

    This big guy is Hippasteria muscipula! A species I just described last year! (here) It would seem to occur over a pretty wide depth range..from several hundreds to several THOUSANDS of meters!

    They seem to be primarily predators on bamboo "corals" which are octocorals in the family Isididae.
    and there was THIS stunning image showing H. muscipula but with 3 polynoid worms crawling around on its body surface. This is unusual, since polynoid worms usually crawl on the oral surface in the tube foot grooves..

    Another closely related Hippasteria-like sea star which we've seen in the Hawaii region is the genus Evoplosoma.  



    This shot is just awesome. We can see its stomach and tube feet hard at work clearing off the meat from the bamboo coral's stalk..

    BUT that's not all! We've encountered multiple goniasterid species apparently feeding on coral! 

    1. Astroceramus eldredgei

    2. Calliaster pedicellaris
    This species was described by Walter K. Fisher in 1906 and VERY rarely seen since then. 
    3. Circeaster pullus
    Here's another species I described back in 2006 and named in honor of Dr. Craig Young at the Oregon Institute of Marine Biology. It was observed perched on this coral skeleton where it was presumably feeding..

    Have not seen any of these on the Okeanos dives as yet though.

    4. Circeaster arandae
    This one was a surprise because it very much looks like a species I described in 2006 from Madagascar!!  But it lives in deep, DEEP water (>1000 m) which is consistent with my earlier account. But weird to find it so far off..


    How many more octocoral predators will we see??


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    Leg 4 of the Hohonu Moana Okeanos Explorer Expedition has begun! (here is the link to live feed!)


    We have new investigators Scott France (on invertebrates) and MacKenzie Gerringer (on fishes) studying the huge diversity of deep-sea corals, sponges and other life in the northern Hawaiian Islands region.

    The Hawaiian region brings with it a very different fauna from the one we saw in the Atlantic Okeanos cruises. There's actually quite a bit more diversity in the Pacific in sea stars, and many other echinoderms. So I thought I would offer a guide to some of the more prominent groups of echinoderms that we are likely to encounter in these deep-sea habitats: the sea urchins!!

    Most everyone is familiar with the spiny balls that one observes in the intertidal or while SCUBA diving. 
    Burrowing Urchin, Echinometra mathaei
    And basically, sea urchins in the deep appear the same.. BUT many of them are unusual in some way.  Different adaptations or different evolutionary histories and there's much more to them than the "typical" urchins most people encounter in shallower depths. 

    Here are some of the more commonly encountered sea urchins we will likely encounter in the Hawaiian region (below about 1000 m). These are also pretty typical of deep-sea settings throughout the Indo-Pacific.

    There ARE a few that aren't noted here. Mostly the "irregular" urchins such as sand dollars, or sea biscuits. 


    1. Aspidodiadema This is a genus of unusual deep-sea urchins that is represented in Hawaii and in many tropical deep-sea habitats in the Pacific as well as one species in the Atlantic. These have really long spines that it uses for locomotion in conjunction with its tube feet.

    There's apparently more than one species of Aspidodiadema in Hawaii, but so far we've been calling the one seen by Okeanos, Aspidodiadema hawaiiense. Upon looking at both images, there do seem to be some differences but its unclear without a specimen to examine..
    Here's a nice moving GIF of this Aspidodiadema species on the move! 
    This image shows the same type of animal as the one above but with a mysterious bag like extension emerging from the top. Possibly an anal sac as we see in diadematid urchins?? Unclear.
    In comparing them, this second one seems to be lighter in color... 

    2. Caenopedina! This genus is a member of the family Pedinidae, of which it is the only living member. This genus is widely occurring mostly in deep-sea habitats. 

    According to the Hawaiian Undersea Research Lab's Animal ID guide, there are two recognized species in the region: 

    Caenopedina pulchella This species shows these very thick spines which are brightly colored green and purple!
    The small individual above seems to have much smaller spines relative to this larger one.. but the colors patterns appear consistent..

    This second species is Caenopedina hawaiiensis and it seems to show a very different appearance... 
    3. Echinothuriid Urchins! These are one of the most frequently encountered sea urchins in deep-sea settings. Commonly referred to as "pancake urchins" or "tam o shanter" urchins, their body shape is suspended by water pressure, so when removed from the ocean into say, a bucket on the deck of a ship, their very soft skeletons collapse into a flat "pancake" like shape.

    I've written on these animals plenty of times hereand here and their shallow-water relatives here

    One caveat about this section: I'm not sure that any of these can be correctly identified..so I'm keeping it vague. At least for now. 

    But salient features of the urchins as a group include: 
    1. Needle sharp spines which can be pretty dang painful!
    2. Cute little walking legs with special "hooves" on their spines 
    We've seen at least 2 species.. this purple species..
    Rewatching yesterday's #okeanos dive: sea #urchin w/ mittens on its spines #Hawaii, Lone Cone ~1800m pic.twitter.com/kEL4cTtBIn
    There's this slightly different pink echinothuriid
     this grey species                            

    Echinothuriids are a frequently encountered group in the deep-sea. We will likely encounter more of them..

    4. Cidaroid Urchins! One of the other "typical" urchins one encounters in the deep-sea is that cidaroids.  This is a fairly old group of urchins, which branched off early in the history of urchins and has a fairly good Mesozoic fossil record (see here).   

    Cidaroids are unusual for urchins in that they lack skin on their spines, which results in an overabundance of "fouling" animals which can settle and grow on them. I've briefly talked about the ecological importance of this here. 

    We've also seen cidaroids with a CRAZY range of spine shapes and morphologies, such as what I summarized here
                               
    Cidaroids are not just predators on corals as shown below, but are also likely predators on stalked and other crinoids as I've posted about previously..

    A nice diversity of cidaroid urchins in the deep-sea Hawaiian Islands.. More at the HURL gallery here  but sadly we've really only seen a few at the deep depths Okeanos has been exploring..

    Histocidaris variabilis.. note the barnacles growing on the spines...


    Stereocidaris hawaiiensis

    Possibly Stylocidaris calacantha.  This one was observed high up in the branches of this bamboo coral, likely feeding on the polyps..


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