What is the invertebrate animal (without a backbone) that fascinates you the most?

The octopus. It is so flexible it can slide through small openings. It can change color. In labs where they placed its food inside glass jars it was smart enough to be able to open those jars by twisting off the lids.

Spider, Ant, Butterfly, Termite, Lobster, Crab, Squid, Octopus, Scorpion, Cockroach, Ladybug, Moth, Bee, Wasp, Fly, Flea, Mosquito, Worm, Caterpillar, Slug, Snail, Walking Stick, Centipede, Millipede, Praying Mantis, Dragonfly, Tick, Tapeworm, Grasshopper, Locust, Tarantula, Beetle. Choose your favorite 10. To all those people who wrote down snake. Mammals, Birds, Reptiles, Fish, and Amphibians belong to a group of animals called vertebrates meaning backbone meaning they all HAVE backbones. I hope you people are no older than eight. I learned this when I was eight. P.S. Crying??? I'm already filling the room with my tears. cab_must_die, were you thinking of animals WITH backbones?

Um.. sharks have a cartilaginous skeletal system along with dermal bone.. don't *really* qualify as "invertebrates".. but okay.

I agree with the Octopus - they're incredibly intelligent for an invertebrate and their use of color is fascinating.

the giant, and colossal squid, no one knew it truly exsisted til about 50 years ago. no one knows how long these things can get.

plus they have only ever been photographed and filmed once in their natural habitat.

i find it fascinating how something potentionaly so big can be so elusive, some estimates put it at over 100ft

I would say cuttlefish. They actually communicate with each other by changing the color of their skin in rippling patterns. They are also experts at camoflauge, more adaptable than octopi, and capable of some sneaky, playful behavior.

Sharks

Hey I was going to say jellyfish. lol

amoebas hehe