We are spineless and tend to be shellfish. We can be crabby or just a little shrimp. Cladistically we can bug you.

What do you call a cow with no legs? Hint: two words but don't put a space between them

If you come to the sea you'll have a whale of a time, Expensive by boat; on shore won't cost a dime, You'll hear me breathe as my fin breaks the surface, I may look like a shark, I swear we don't do it on porpoise!

Up a tree, in a box, on a warm windowsill, An elite predator, but you house me still, I come in all shapes and sizes; bald or with fur, Give me a lap and a pet and you might hear me purr.

OSHA would hate my work conditions, full of lava pits and turtle collisions.