kottke.org posts about marinebiology
Although it's widely accepted that the scream heard when a lobster is dropped into a pot of boiling water is a bunch of hot air, it turns out that some crustaceans do feel pain, and have the capacity to remember it.
Some crabs that evacuated attacked the shell in the manner seen in a shell fight. Most crabs, however, did not evacuate at the stimulus level we used, but when these were subsequently offered a new shell, shocked crabs were more likely to approach and enter the new shell. Furthermore, they approached that shell more quickly, investigated it for a shorter time and used fewer cheliped probes within the aperture prior to moving in. Thus the experience of the shock altered future behaviour in a manner consistent with a marked shift in motivation to get a new shell to replace the one occupied. The results are consistent with the idea of pain in these animals.
And for a more eloquent take on the struggles of our shelled undersea edibles, there's always David Foster Wallace's riveting essay, "Consider the Lobster."
Sea urchins have teeth so powerful they can munch through limestone. These teeth are composed of calcite, a form of calcium carbonate, which happens to be the same material in the limestone they're snacking on. So how do they chomp through the rock without grinding down their tusks? By aligning the calcite crystals that make up their teeth.
The structure and composition of the tip, particularly the orientation of the calcite crystals, is exquisitely controlled.
Maybe as dentists investigate how to spur humans to generate teeth like sharks, they can devise a way to make them as strong as those of a sea urchin. A scary prospect when you think about playing hockey.
Crinoids, or sea lilies, are marine animals that resemble plants. Unlike its garden namesake, the sea lily doesn't stay still, but creeps along to avoid becoming prey for sea urchins and other predators.
It seems they've also developed the ability to "shed" their stalk-like appendages.
"It's the lizard's tail strategy," said Baumiller, who is also a curator in the UM Museum of Paleontology. "The sea lily just leaves the stalk end behind. The sea urchin is preoccupied going after that, and the sea lily crawls away." And the speed at which they move---three to four centimeters per second---suggests that "in a race with a sea urchin, the sea lily would probably win."
When on the move, they resemble graceful spiders in a hurry.
Crinoids are also the state fossil of Missouri, and inspired the design of Pokemon characters Lileep and Cradily.