Octopus

Octopi are a breed of multi-tentacles cephalopods that live within the ocean. They make their homes along the bottom of the sea, particularly within coral reefs. Octopi are quite intelligent as Mollusks go and capable of complex tactics in their pursuit of food.

Combat
Many have evolved the ability to blend into their environment. They can not only change the color of their skin, but also use muscle action to change its texture to appear more like whatever they are blending against. If they are pursued by predators, octopi are capable of expelling a cloud of ink before swimming away. Some octopi are venomous, capable of producing a paralytic neurotoxin.