I got my cable box set up to record it. I can’t wait.
Link to Opabinia.
Link to fossils of Opabinia and Parapeytoia, an anomalocarid with arthropod legs.
Unfortunately, these guys have been extinct for some time (like a half billion years).
Mermaidens.
Then I daresay that, etymology notwithstanding, this gives them a much better claim to “correctness” than the obscure Greek plural. Current usage, not long-forgotten linguistic ancestry, determines standard spelling.
If you agree with this line of thinking, then why should it be any less a travesty to put an English plural on a Greek word? I bet you use the English plural on lots of other words of foreign origin without a second thought.
I thought my point was that there was no “correct” plural (just various incorrect ones), which is why it was a trick question (and, for me at least, funny. 
).
As I said before,
“My mouses are all cheering in their little hice over the rationality of English.”
Though it is even more funny to see the pedantic use “octopi” as if it were “more correct” than the plebian “octopuses”, when neither is strictly “correct” (or if they are, they are for the same reason - common usage). Who could resist the temptation to deflate the pompous, with the application of a pomposity even more grand? Not I. 
I still prefer “octopussies” even though it sounds like some kind of freaky Japanese porn.
Aye! Would you happen to be familiar with “The Clean Song”?
This site introduced me to the unusual “Mantis Shrimp”. I figured that was the coolest until I read about that mimic-Octopus!
Try MSN searching. It only gives two links, though.
Obvious, since nobody seems to have heard of it.
Try looking in some books…
And I’m Bong, by the way.
Kind of obvious since I seem to be the only person on earth who know about the thing.
And they’re extinct.
I needed to register a new account since it seems like my password for the bong account got emailed to a nauruan multiorganism porn site, which explains why I didn’t get my password after about 200 tries.
Might to contact a higherup about it…
a happy elf!
;j
Coolest marine creature?
Its got to be the Sawfish
What does a Hallucigenia or a Seymoria look like?
But those things are COOL.
And of all the things in the world, they made a pokemon out of a crinoid and an anomalocaris.
And the anomolocaris pokemon looks like godzilla, and the other guy looks like a head attached to a plant.
Cooooooooooooooooool…
Yeah, Peyote Coyote, CARCHARODON MEGALODON rocks.
Check this out. Imagine a great white shark at 50 ft., 100 ft. or bigger. Fairly plain looking, except for scale.
“We’re gonna need a bigger boat,” is right.
I’ll second the ** cuttlefish ** and I’ll add ** seahorses ** and the ** leatherback turtle ** (although it does spend some time on land)
hebesphenomegacorona: Lots of folks know about opabinia, you just have to spell it correctly to get google hits on it.
If were going for Burgess shale critters, I nominate Anomalocaris. Three’s a nice animation of one swimming here:
http://www.geocities.com/goniagnostus/anohome.html
And they’re estimated to have gotten up to 6 feet long. DAMN!
I have the Burgess shale playset, it’s a collection of little plastic models of the burgess shale critters. 
As for extant underwater critters, the nominations of mimic octopus, giant squid, elbow squid, cuttlefish, and also the ancient paper nautilus work for me. I’m a fan of pretty much all cephalopods. Around here, it’s not too hard to find octopodes in the wild, and I love petting them. They’re so soft. Squid are also seen regularly, but I have yet to see a wild cuttlefish. I keep hoping.
I finally saw a stomatopod in the wild a week ago, after years of wanting to. I agree with casdave, they’re utterly cool. They can differentiate between various polarizations of light, and appear to use polarized patterns on their meral scales to communicate with each other. And rather than binocular vision, like us, with the three foci on their two eyes, they have hexnocular vision. Also, their raptorial appendages perform one of the fastest motions in the animal kingdom, smashing or stabbing prey in I think 1/2000 of a second. The bigger ones get to about 14 inches long.
I once had a volunteer job at the Woods Hole MBL. I was in charge of taking squid out of the squid tank if they’d died. My “pay” was several giant horshoe crab (limulus polyphemus) shells. I love horsheshoe crabs, even if they are chelicerates. I agree with…uh, whoever it was; imagining them being the same, so far back in time, is really quite wonderful.
I don’t know if they’re the coolest, but my favorite marine creature are lobsters. They’re adorable. I can find spiny lobster almost every time I go snorkeling here, and I like to pet their spiky antennae. They’re so cute! It makes me sad that people haul them out of the water as food.
Oopppsssss…
That explains why I didn’t get any hits!
Ooh, so many to pick from! I’d have to say that far and away my favorite group is the octopodes/pi/puses. I collect octopus “stuff”- figurines, photos, plush toys, etc. But I have many other favorite sea creatures.
The manatee is definitely a favorite, due to appearance and personality. So cute and tubby! I love their little whiskers. I also love walruses, again, probably the whiskers.
Rays, especially manta rays, are awesome. I saw a Discovery Channel show once a long time ago where a diver actually hitched a ride on a giant manta ray.
Sharks are always very cool for the scare factor.
I love marine invertebrates, especially marine snails. I’ve always loved snails period, and marine snails as mentioned are like super predator snails. Very diferent from their docile land cousins.
The nudibranch is also cool, especially the more colorful forms.
About keeping octopuses as pets, it can be done, but it is very expensive and time-consuming. My late father was one of those aquarium junkies, and he kept about every sort of tropical fish possible over the years. Octopuses are usually only available from dealers specializing in exotic marine life, and they’re expensive. They also have very specific tank requirements- you have to have a very powerful filtration system for them since they need very high water quality, and if an octo inks and can’t get away from it, it can suffocate itself. They are also very shy and will usually hide all day until the lights go off. They’ll eat anything else in the tank with them as well. You must give them many hiding places and you can’t stare at them until they’re used to you. They’re very susceptible to stress and it can kill them. They’re definitely not for inexperienced keepers.