Five Invertebrates that would be Terrifying if they were Bigger!

The secret of the big terrifying jaws is #1 below! 

HALLOWEEN! Every year, I like to use the season's festive theme to try and highlight some cool invertebrate diversity! Last year I did an overview of creepy worms and the year before that, I did an overview of spooky things that echinoderms (my research focus & subject of this blog's love) are known to do. 

So, note that I actually am using REAL aspects of these animal's biology that make them, creepy, terrifying, spooky, whatever. Unlike SOME places.. I won't just find some weird looking, random animal and just SAY its spooky or creepy. It actually HAS to do something worthy of the name!

This year: a theme that often comes up with invertebrates: Predators that would be terrifying if they were larger!! 

So, this is a pretty popular trope and frankly, there are ALREADY a bunch of huge, oversized marine invertebrates that freak people out. You will doubtlessly see some tweets about those beasts this week.

Here are some of my picks for invertebrate PREDATORS that to me, have earned the RIGHT to be optioned for movie rights! or other fantastic treatment!  So, nothing that is weird looking but harmless (I mean, c'mon, BASKING SHARKS? SHREWS?)

There were MANY to choose from of course and so perhaps next year I'll present more of them. But for now, here's some good ones.....

5. Arrow Worms (phylum Chaetognatha)
Imagine the oceans filled with fast-swimming, transparent worms with sharp spines for teeth on their head, and which can effectively "see" in a 360 degree field of view AND attack and devour prey several times their own size.

Bodies are transparent and with unusual "eyes" that are arrayed in 5 directions, essentially giving them a full field view (360 degrees). Fortunately, these "eyes" lack lenses and are thought primarily to be used for orienting to light and dark.
They feed with these big nasty hooks that emerge off the front of the head!!  Some are even known to do so with venoms like tetrodotoxin, the potent toxin from puffer fish.

Arrow worms have been documented as having capture prey several times their size...like fish!

Here's an interesting video that shows the spines extending from the head on a Japanese species... 

Sadly, or perhaps fortunately for us.. these are pretty small. Ranging from less than half an inch with monsters up to 4 inches! 

But what if they were HUGE????  Honestly, I think one movie from 1998, Deep Rising had these things, which swam through the water at a good clip. and the spines were KINDA chaetognath like! 

So, yes! We want MORE ARROW WORM MONSTERS PLEASE!!! 

Via Wikipedia

4. Cone Snails.  Does everyone know what cone snails are? Marine snails that use a modified tooth like a harpoon + very potent toxins to capture their highly mobile prey. Often times, vertebrates like fish..

Some of them, however, rather than using the proboscis to directly paralyze prey, will use this  highly modified "net" which is presumably, a modified feeding proboscis.. 

Yikes.. imagine what that would be like if cone snails were bigger..like bear or even elephant sized! 

3. Rhizocephalans! Barnacle Parasites that take command of your Body! 
Imagine  a fleshy parasitic network that works its way into your body, commandeering your all your bodily functions, INCLUDING your gonads, such that all you do is produce eggs to make NEW parasites.

These don't really NEED to be bigger..but merely adjusted to parasitizing MORE than crabs.

These have been written about in some detail by Rebecca Helm over at Deep Sea News. Her account is quite chilling. I recommend reading it in the dark, while you are alone with some seafood....

Or, watch this video from Casey Dunn's "Creature Cast" series which also very ably explains the life of this creepy parasitic barnacle... 

                Rhizocephala: The Extraordinary Life Cycle of a Parasitic Barnacle from Steph Y on Vimeo.

2. LEECHES! This is kind of a cheat, since I put leeches into my "Creepiest Worms" post last year.  I just thought this was kind of awesome... 

1. Labidiaster annulatus, the giant 50 armed star of the Antarctic!
This is one of my FAVORITE beasts.. which I wrote up here, early on in the blog (and on numerous other occasions).
But the short story:  Giant 1.5 foot wide starfish with 50 arms, catches krill and other prey with arms!!                  

The surface of the starfish, especially on the arms is covered by THESE.. 

Jaw like structures called pedicellariae which act as "bear traps" to capture krill and other prey if they get too close to the arms. 

Thanks to Bob Ford & Taylor Steed of Frederick University for the SEM pics

These are ALREADY pretty big. About 1-2 mm. But look at those fangs!!  and the shanks on the teeth!

Can you IMAGINE if this critter was DOG or even BEAR sized on the land????  Catching everything from tiny mammals to birds!!! 

For the Next few weeks: Echinoblog Returns to PARIS!

Coelopleurus! The most gorgeous urchin you never heard of!

This week, I thought I'd share some gorgeous sea urchin love! Behold Coelopleurus! 

What's that? You've never HEARD of Coelopleurus??  Well, that's about right, I suppose. Its a distinctive looking enough species but it lives in slightly deeper water than is typical for most casual SCUBA divers or vacationing snorkelers..

Described by Louis Agassiz in 1840, Coelopleurus is a genus in the family Arbaciidae. There are about 14 known species. Eleven living species and four fossils.  

Coelopleurus is a deep-sea urchin, but on the shallow side, about 75 to 500 meters. They occur primarily in the tropics, but across the Atlantic, Pacific and Indian Oceans. 

Biology of these animals is poorly known. 

Based on one study on the gut contents of the Atlantic species Coelopleurus floridanus, we know that it is a possible predator of the octocoral Telesto, as well as bryozoans, worm tubes and sediment.  The octocoral Telesto looks like this and occurs in pretty shallow water. Learn more about it here.

It is also kind of unusual because it is one of the few sea urchins that displays secondary sex characteristics.. i.e., you can tell the females from the males when the males are spawning. 

You see that structure that the red arrows are pointing to?? 

That is the male "papillae". And in "C" you can see sperm being ejected into the water column. Yow!! This image is from a paper by Dave Pawson and John E. Miller in the Bulletin of Marine Science, 1979. 29(4): 581-586.  

Coelopleurus is unusual because it has these big, long curved spines BUT they are brilliantly colored in red and white!

But even MORE than that?? The tests (i.e., the skeletons) are brightly colored with these very striking patterns that seem to be rather variable..

Here is the test of Coelopleurus floridanus... 

But here's one that is considered the SAME species but a LARGER specimen.... Honestly.. it wasn't clear to me how important the patterns were to identifying each species.

The colors and patterns are embedded in the skeleton. So, if you drop them in a preservative like alcohol, the reds and purples, and etc. don't go away. They remain after death.

Here's another species. This one is from Japan... Coelopleurus undulatus from M. Shigei. 1986. The sea urchins of Sagami Bay. Biological Laboratory, Imperial Household, Maruzen Co. Ltd, Japan.

Gorgeous and amazing. 

Image from the NHM Echinoid database

Here is the most recently described species, Coelopleurus exquisitus which had the distinction of being described, in part from specimens purchased from the online auction house Ebay in 2006. 

Here again, is the very distinctive and unusual color pattern observed in this species... 

But wait! Coelopleurus also occurs in the fossil record!!  Here's Coelopleurus coronaformis from the Cenozoic of Mexico (< 66 million years ago) so pretty recent..

Here's Coelopleurus coronalis from the Eocene of Barcelona, Spain... 

Five Points About The Fossil History of Echinoderms! Happy National Fossil Day!

Happy National Fossil Day!
Every few years I'm in a position to share some more love about echinoderms and fossils. I've done this on previous National Fossil Days and tried to shed some light on the often arcane world of fossil echinoderms...

Here's one on paleocology & fossil parasites..

A nice gallery of fossil crinoids..   and this classic piece on giant floating/pelagic crinoids! 

Paleozoic Echinoderms: The Ophiocystioids!  and the Helicoplacoids! 

A LOT of the REALLY weird stuff in echinoderms takes place in the days of the Paleozoic, some 245 to 541 MILLION YEARS Ago... There was a lot of crazy stuff (evolutionarily speaking) happening then. Echinoderms, as a lineage PREDATE Dinosaurs and they've been around since before vertebrates walked on land.

But here's a bunch of interesting facts I've cobbled together to better understand and appreciate fossil echinoderms and their history!!

5. Animal Body Type can bias preservation. This is really a dynamic of fossil preservation which is true for almost ANYTHING. In order for animals or any organism to undergo the fossilization process, it has to "survive" long enough to be buried and then kept together so that it undergoes the process.  MANY factors can affect which animals/organisms/whatever are preserved in the fossil record. The study of how different factors affect fossil preservation is called taphonomy and it affects our perception of the history of life on the planet.

One of those factors is the physical strength of the body itself. Is it delicate? Is it REALLY strong and tough?? Delicate, soft bodies tend NOT to preserve very well (although they can exceptionally) but some bodies with very heavy and strongly calcified bodies are MORE likely to preserve.

So for example, these starfish, in life would have a fairly chalky body. They hold together pretty well when all the tissue is removed.

Here's a whole bunch of crinoid stems preserved in limestone. These are pieces of the "stalk" in stalked crinoids. Hard parts that are pretty structurally solid. You're most likely to find this of all the pieces of a crinoid (aka a "stone lily").

4. Preservation Environment is important. So, here's the thing. The fossilization process requires pretty RAPID burial of the subject organism/animal, whatever for fossilization to eventually take place.  Which brings us to another "bias" of preservation: The environment!!

If the animal lives in an environment in which it is predisposed to be buried ANYWAY, that makes it THAT much MORE likely that it will be preserved. One good example are sand dollars (or really anything which lives buried).

Sand dollars have a pretty solid skeleton but ALSO live buried in sand. Sometimes, they can be killed by burial and pretty much just get preserved there in the sediment as it turns into rock.
                           

and voila! (yes, its not the same species but play along, its not easy finding matching videos and pictures of fossil sand dollars! )

3. There were MORE KINDS of Echinoderms in the Paleozoic!
One of the oldest questions from biologists unfamiliar with the fossil record is, "Why haven't you completely figured out the evolutionary history (i.e. phylogeny) of Echinoderms yet?? There's only FIVE of them!"

Yes. Only five LIVING groups (crinoids, sea stars, brittle stars, sea urchins & sea cucumbers) are around today. BUT when you get into the VERY earliest days of echinoderms in the Paleozoic (245-541 MILLION years ago), you have easily TRIPLE the number of groups! (i.e. classes) and a crazy diversity of body plans NOT seen today!

You got things that look like crinoids. Disc-shaped echinoderms. Accordian-shaped, asymmetrical echinoderms. Weird, crazy tentacle-balls. and all sorts of natural "experiments" in Echinoderm morphology.

A crazy panoply of things! Oh, to go back in a time machine to see when rock was young!

                           
2. The Roots of Recent Echinoderms were there...
Picking up on the crazy, diversity of echinoderms mentioned above its worth mentioning that the ancestors of MODERN echinoderms were seen among them.

Ophiocistioids for example are intermediate between sea urchins and sea cucumbers.

Also in the Paleozoic, we had the early ancestors to brittle stars and sea stars.  Today, the brittle stars and sea stars distinctive looking in appearance that we can easily tell them apart, but looking at those early forms was NOT so easy...

Can you imagine walking around in the Paleozoic seas and seeing something that was NOT quite a starfish but also NOT quite a brittle star!! Something in between....

That's kind of why some paleontologists get so twitchy about what you call a "sea star" versus a "brittle star". They have LITERALLY spent years arguing WHY that is the case..

1. The Permian/Triassic Extinction Changed everything
So, then at the END of the Paleozoic, in the Permian, you have one of the most devastating MASS EXTINCTIONS known to life on Earth at the Permian-Triassic Boundary. That is the end of the Paleozoic and the beginning of the Mesozoic (i..e time of the dinosaurs).

This extinction was huge. 96% of marine species were wiped out. Part of this? All those aforementioned echinoderm classes.. (about 15 of them)? GONE.

Only survivors from FIVE groups survived to live on today.   Here's a cartoon of this from Echinoblog Art Department!

Echinoblog Art Department Lives on!

Any one of these could be a whole blog post but this gives you a short summary of some dynamics involved with the rich fossil history of the Echinoderms! Happy National Fossil Day! 

What is that WEIRD THING on FACEBOOK???

So by now, everyone and their 3 best friends have seen the critter above and the video on Facebook (below) which seems to have freaked everyone the frack out. Its been circulated and seen by over 5.6 million people!!

Post by Jr Saim.

And everyone keeps on asking WHAT IS IT?? I've received this video now, what feels like a million, jillion times from people who want.. nay, DEMAND to know:  What IS IT???

Answer: A basket star. A distant relative of sea stars.

First thing: HARMLESS.  and out of its element. But we don't know much about them.

This was even given time by IFLS but not being echinoderm specialists, their answer was a bit over generalized... So, here's MORE. Its actually a pretty neat beast.

1. This is a BASKET STAR. These are specialized ophiuroids. Ophiuroids are members of the phylum Echinodermata. In other words, its related to Sea Stars, sea urchins, etc. Basket stars in particular have a highly branched system of arms which they use to feed. I've discussed the feeding biology of basket stars here.  They have hooks on those branches with which they feed on tiny bits of food.

There are actually several different groups (i.e., families) of ophiuroids which have these fleshy arms and highly branched arms.They occur widely and vary from habitat to habitat.

2. Euryale aspera?  I've consulted with one of the world's experts on basket stars and euryalinid brittle stars, my colleague Dr. Masanori Okanishi, currently at Kyoto University. Discussions with him and checking my own resources suggests that the animal above is a shallow-water tropical species, called Euryale aspera. Identification of the species is uncertain since there was only a picture and no specimen but based on my cross-check, this seems like a likely name.


3. Where and HOW does it live? Euryale aspera is a shallow water species which occurs widely across the Indo-Pacifc. This species is found throughout the Indo-Pacific, from Asia but as far west as Madagascar in the Indian Ocean.

As with other basket stars, feeding is accomplished via tiny hooks present on the MANY branching arms spread out into the water column when they feed.

Here are some videos of various Japanese basket stars which MIGHT be Euryale aspera. Its difficult to ID these from images, but these give you an idea of how they live. Arms up in the water during ideal water flow, but withdrawn when not feeding.

4. What does the name mean? So, as you may have noticed from one of my earlier posts, one of the better known genera of basket stars is called Gorgonocephalus. "Cephalus" means head while "Gorgon" refers to the head of Medusa and her sisters: The Gorgons of ancient Greek Myth. One of Medusa's sisters is named EURYALE. She was identical to Medusa in appearance with snakes for hair and transformed men into stone with her gaze. Thus, the genus of this other "basket star" follows the theme of a "medusa's head" type appearance. The species name "aspera" is Latin and a references a descriptor for "rough" which likely alludes to the spines and other tiny accessories on the body surface.

Euryale aspera was described in 1816 by the famous zoologist Jean Baptiste Lamarck himself!

5. What about OTHER BASKET STARS???
The term "basket stars" informally refers to several groups of ophiuroids within the order Euryalida, which all have thick, fleshy arms. Some are more serpentine (i.e. serpent stars) whereas others are branching and appear to form a "basket" (i.e., basket stars). But they are often similar in appearance leading once again to some "blurred lines" where common names are applied. There are about 177 species in five families.

Members of the Euryalida occur widely throughout the ocean depths. Many are shallow water, occurring in both cold and tropical habitats whereas others occur in the deep, deep sea (> 1000 m). Many of them occur at depths in between. But you can encounter basket stars at SCUBA depths on reefs or other shallow habitats, which is where the "creature" above was apparently collected from.

A "serpent star" (Asteroporpa annulata from the tropical Atlantic)

A "basket star"


And by the way, these have been caught on deck and seen before... 


The original video indicates that the one collected was returned to the ocean. These don't take exposure very well.. but perhaps more adverse to the animal was its ability to re-establish a perch to resume feeding. But, frankly our knowledge of their biology is very poor. We don't know much about them.

A panoply of Pycnogonid (sea spider) biology from the latest round of Okeanos Explorer

So, after a few days of bad weather, we finally finished this last round of the 2014 Okeanos Explorer's dives into the North Atlantic! 

BUT we were not left high and dry! There was an unusual abundance of GREAT observations! But wow! there were some SPECTACULAR SEA SPIDER aka Pycnogonid biology events seen! Especially on the last few dives.. 

I have a soft spot for these. I did a previous post on the very colorful ones that live in shallow-water tropical habitats here. 

I don't know a lot about pycnogonid biology, but its a pretty sure bet that a lot of what they do is poorly known, especially in deep-sea species. 

Most of the observations below took place below 1000 m, most were probably between 1000 and 2000 m.  Some pretty rarely seen (or maybe first time) sightings. 

Most of these were screen grabs I took.. but my thanks to the Facebook Underwater Screengrab group, Carina Tsottbauer (@CarinaDSLR) and Nicole Morgan (@coralnerd)! for their help! 

1. From Atlantis II Seamount. This Daddy Pycnogonid with a brood clutch of eggs!

2.  From Nantucket Canyon. This pycnogonid with an arcturid isopod on its proboscis (ID thanks to Tammy Horton). Not sure why its there. Possibly food or??

3. From Physalia Seamount! A big sea spider, possibly Colossendeis, caught in the act of extending its proboscis into this large solitary hydroid! Woo! An in situ feeding observation! 

4. From Physalia Seamount, a pycnogonid in this sediment depression! Possibly feeding on a burrowing anemone? 

5. This pycnogonid in Nantucket Canyon hanging out with some single cup corals.. 

6. From McMaster Canyon! A swimming pycnogonid! 

Wow! at first I thought this might be novel.. but thanks to Twitter (@tammy_horton) and quick communication with Tammy Horton, curator of the Discovery collection at Southampton, and deep-sea arthropod biologist extraordinaire! It turns out that there ARE some records of swimming sea spiders in the scientific literature from 1977!!