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!
Chloeia is a fairly conspicuous polychaete worm in the family Amphinomidae which apparently occurs widely throughout the Indo-Pacific. About 27 species..and honestly I'm not sure if everything that is labelled C. flava in the videos and pics IS correctly identified but here's a round up of videos and pics while I am distracted by a job interview!
This one shows some burrowing action at the end...
More
Here's one eating...
This one is a stunning iridescent green! Image by friscodive
Chloeia fusca. Image by Ben Naden
Another similar one. Image by divemecressi
And yet another by friscodive
An awesome one from the Panama Canal. Image by Arthur Anker
Back atcha next week with more echinoderm blog love!
Our paper addresses how Antarctic echinoderms but specifically sea stars (=starfish) and brittle stars are likely to be vulnerable as the climate changes, creating a more acidic ocean environment.
Here is a quick video that nicely summarizes the broader phenomena of Ocean Acidification (abbreviated OA)
But here is where we add further details-the acidification? affects different kinds of calcium carbonate (the material which composes shells, coral skeletons, etc.) differently...
Most of the shells and skeletons that you read about in the news are usually made either out of different forms of calcium carbonate-either aragonite (wikipedia has a nice summary here) or calcite. Aragonite is usually what's seen as associated with shells, skeletons, etc..
But, of course, echinoderms being echinoderms have something a little different going on... Echinoderms have skeletons with a high concentration of magnesium (Mg).
Their skeletons are composed of Mg-calcite (magnesium calcite)
Mg-calcite is even MORE soluble (and more vulnerable) than aragonite!
Looking at Mg-calcite in Antarctic Echinoderms
McClintock and his team sampled some 26 species of echinoderms, representing all 5 living classes (sea stars, brittle stars, crinoids, sea urchins, sea cucumbers) and analyzed them for % composition of Mg calcite.
The sampled specimens showed that skeletal components in Anatarctic echinoderms met the defined standards for "high-Mg-calcite species" (MORE than 4% Mg-calcite by mol%)
Of all the echinoderms? Which had the HIGHEST amount of Mg-calcite by % weight??
Several species of Starfish!
I would note that ophiuroids were not heavily sampled-below but in all liklihood they are just as if not more important here..
Specfically, this very widespread species, Porania antarctica dsplayed among the HIGHEST % weight of Mg-Calcite
In the above image-the animal looks quite fleshy but in a dried one below..you can see there's actually quite a bit going on...
And here are some rather large Macroptychaster in a pic seen around the world..but you can see how big they get. The % of Mg-calcite is quite high in this and many other Antarctic asteroid species...
One major conclusion: Antarctic echinoderms-especially sea stars (starfish) have high amounts (in terms of % of total weight) of Mg-calcite in their skeletons.
Mg-calcite is more inclined to dissolve as a result from OA and therefore makes them highly vulnerable to dissolution!
This total amount of Mg-calcite was compared relative to OTHER %of Wt. values across different latitudes (0=equator, higher = closer to Antarctica)
Note the datapoints indicated by the RED ARROW. Those are the data from Antarctic taxa.
There's a global pattern that shows that those echinoderms close to the tropics have, by weight, the greatest % of Mg-calcite. This makes sense when you think about how heavily calcified tropical starfish are (such as this Protoreaster nodosus)
So, if tropical echinoderms have the greatest % of Mg-calcite by weight, why are we worried the MOST about POLAR species???
An excellent question. Here are some answers.
1. Temperature is an important part of the "calcium carbonate in sea water" ocean chemistry dynamic. Cold water settings, such as the Arctic and the Antarctic have shown the most dramatic decreases in the amount of calcium carbonate available for shell/skeleton building as ocean acidification increases. This has been shown most recently in pteropod mollusks (click here for ref)
3. Echinoderms are a dominant force in the Antarctic. They have HUGE biomass. In other words there's a LOT of them and they're important to the global carbon cycle. Notice the large numbers of sea stars in the video below...That is a lot of Mg-calcite...
Thus, Antarctic species may not have the highest % of Mg-calcite across the full "band" of possibilities but they are among the MOST vulnerable.
So-all this leads to an important realization:
Echinoderms, probably sea stars, will probably be an important, I daresay, critical indicator of which faunas will be affected as climate change continues and ocean acidification creates a more acidic ocean environment.
This could affect the larval development, the physiology or the ecology of these species. Its also important to realize that echinoderms have an endoskeleton as opposed to a shell which is what you see in other studied taxa... MUCH more remains to be studied.
Its also interesting to note the prior extinctions of echinoderms and other echinoderms from Antarctica as I've mentioned here , possibly during the Eocene glaciation event.
Things got a bit busy this week and I've been discovering the wonders of the natural history side of DeviantArt!
MANY creative and wonderful artists out there and I thought it would be cool to showcase some of the notable ones, especially the ones that can be compared against the "originals"
Frankly, I'm pretty impressed. At one time, a LOT of these animals were known only to a handful of specialists in the world. And NOW?People make them into art!! That's amazing!
What follows here are some PALEOZOIC fossils, with added colors and "reconstructed" onto a Paleozoic sea bottom as if they were alive... I try to compare some of these with actual fossils...
Here is an actual fossil of the ophiocistioid Eucladia from Yale's collection
Cystoid echinoderms from the Paleozoic! I'll blog more about the various Paleozoic echinoderms some day, but there's easily as many extinct echinoderm fossil groups (most of them with stems) as living groups. This image has a nice assortment of them from the Ordovician of New York..
Here are the three primary critters for comparison! The light olive one in the upper right corner, wrapped around the bryozoans is called Cupulocrinus jewetti
Here's another.. the brown one with all the unusual spines? tentacles along the sides? Is identified as Glyptocystites multiporus. Here's a fossil from the Ordovician in Ontario for comparison
Today, a little diversion from echinoderm as we feature, once again, the stunning invertebrate zoology photography of Arthur Anker featuring some of his favorite animals!
A "strawberry crab" (Pelia mutica) from the Honduras
wow! A festive decorator spider crab called Cyclax suborbicularis (Majidae) from Moorea, French Polynesia
A "christmas lights crab (Paractaea rufopunctata)
The spectacular deep-water crab Rochinia crassa
An awesome looking leucosiid crab, Heteronucia venusta from Guam
A stunning Chilean hermit crab (Pagurus edwardsi) infested by a parasitic barnacle (=a rhizocephalan called Peltogasterella gracilis)
A striking striped crab, Liopetrolisthes mitra
An interesting grapsid crab, from French Polynesia
A gorgeous polka dot xanthid crab, Cycloxanthops vittatus from Panama
Stunning red xanthid crab, Liomera rubra from Guam
Fire crab! (Hirsutodynomene sp.)
More polka dots! (Trapezia tigrina)
A flat-rock elbow crab, Cryptopodia fornicata
and wow..there's more which I will add in another post some day!
