and of course 2012 was James Cameron's big dive in the Marianas Trench!
|Image from NPR|
Echinoderms are DEEP. They live in the deepest depths of the ocean..
But how deep are we talking?? Most folks think of "deep" as anything beyond the intertidal.
Many biologists think of "deep-sea" as anything below 200 m, which is where roughly where light stops penetrating. But then you get beyond THAT... then you start entering the REAL deep sea... the ones where biologists start saying stuff like "THAR be where dragons have lease..."
- the Bathyal at roughly 700 to 1000 m
- the Abyssal at about 2000 to 4000 m
- the HADAL from 6000 to 10000 m
Here is a chart from CNN (from the Cameron dive) which gives you a sense of scale about what these zones mean..
|Image from CNN here|
Sources for this survey include Belyaev's "Hadal Bottom Fauna of the World Ocean", the former Online Echinoderm Newsletter World Records page and the Smithsonian NMNH specimen database!
Pourtalesiidae: The "coke bottle" urchins! I have written about these bizarre deep-sea sea urchins before. YES, these are sea urchins, albeit highly strange ones.
They have EXTREMELY thin and delicate skeletons, which can be almost paper thin. They live by burrowin through and digesting mud on the deep-sea bottoms. Records for the genus Pourtalesia sp. (usually only fragments are recovered) have been collected from 6,850 meters in the Java Trench.
Freyellid brisingidan starfish: Freyastera sp. and Freyella sp. Brisingids are starfish that use their arms to pick food out of the water (more here). All the members of the Freyellidae occur in the VERY deepest depths. Typically below 1000m, but many occur between 4000-6000 m. But the deepest record for a freyellid was Freyella kurilokamchatica from 6860 meters.
"Mud Stars" Family Porcellanasteridae. NOW we're talkin. This entire family lives on muddy bottoms deep on the ocean floor, where they swallow massive amounts of mud for food. Similar to the mud star Ctenodiscus (here). The specimen figured below from the NMNH collections is from 6, 250 METERS below the ocean surface! Deepest record for this species, Eremicaster vicinus is from 7,614 meters! These live in the deepest abyssal-hadal bottoms around 4000 to 8000 meters.
Here's a post about their shallower relatives. And you can always find more on my blog about them. Pic below is from 2000 m.
The deepest record for Hymenaster is for a species from 8,400 meters in the Kurile-Kamchatka trench! So, Hymenaster (species remains undetermined) currently holds the record for deepest starfish. But who knows what new specimens and video remain to be discovered!
The plate below is from this paper by Belyaev, G.M. & N.M. Litvinova, 1972: New genera and species of deep-sea Ophiuroidea. - Byull.mosk.Obshch.1spyt. rir. 77, 3: 5-20. (In Russian)
|From Belyev & Litvinova 1972|
- In the upper two boxes is Perlophiura profundissima, which has been collected between 2265 and 8015 meters.
- Lower, left box is Homalophiura madseni, collected from 6156 to 7,230 meters!
- and finally in the lower right hand box is Bathylepta pacifica which occurs between 5740 and 8006 meters! (thanks to Sabine Stohr for tipping me off to the correct species!)
|Bathycrinus carpenteri from the SERPENT website|
There's a LOT of diversity of sea cucumbers at the >5000 meter depth range. All of the swimming sea cucumbers live at these depths (click here)
And of course, our old friends, the SEA PIGS!! (the one shown from 1500 m). Many members of the Elpidiidae, the group to which the sea pigs belong are among the deepest known. Several species occur as deep as 9,500 meters!
But the winning sea cuke? the DEEPEST ones? Members of the Myriotrochidae, including Myriotrochus. Records for these sea cucumbers go down to 10,687 meters!!! The NMNH has records of Myriotrochus bruuni from the Philippine Trench at depths of 10150 to 10190 meters! So yeah, if Cameron didn't see any of these when he was down there? That's HIS problem!
This pic is from a Myriotrochus from the Kara Sea, but you get the idea.
|this image from this Russian page|
So, yeah. Sea Cucumbers. Deep. And don't you forget it!