I have to admit, one of my all-time favorite animals is the octopus. It’s not only an invertebrate, but amazingly intelligent and can be poisonous (like the blue-ring Octopus shown here) or not.
The octopus is an animal because it’s multi-cellular (more than one cell, so amoeba and protists are not animals), it’s moveable (not like a fungus), and a heterotroph (not a plant). Their life cycle starts with a single cell that divides and leads into a multi-celled adult.
All molluscs have a muscular foot on the bottom, and there are three basic shapes: gastropods (snails and slugs), bivalves (oysters and clams), and cephalopods (octpous and squid).
The Indonesian Mimic Octopus, Thaumoctopus mimicus. This fascinating creature was discovered in 1998 off the coast of Sulawesi in Indonesia, the mimic octopus is the first known species to take on the characteristics of multiple species. This octopus is able to copy the physical likeness and movement of more than fifteen different species, including sea snakes, lionfish, flatfish, brittle stars, giant crabs, sea shells, stingrays, jellyfish, sea anemones, and mantis shrimp.
This animal is so intelligent that it is able to discern which dangerous sea creature to impersonate that will present the greatest threat to its current possible predator. For example, scientists observed that when the octopus was attacked by territorial damselfishes, it mimicked the banded sea snake, a known predator of damselfishes.