giant isopods

Maturing to a length between 19 and 37 cm (7.5 to 14.5 in), and maximally reaching a weight of approximately 1.7 kg (3 lb) in B. giganteus, giant isopods are a good example of deep-sea gigantism (cf. giant squid); most other isopods range in size from 1–5 cm.

Although generalist scavengers, these isopods are mostly carnivorous and feed on dead whales, fish, and squid; they may also be active predators of slow-moving prey such as sea cucumbers, sponges, radiolarians, nematodes and other zoobenthos, and perhaps even live fish.

source: http://en.wikipedia.org/wiki/Giant_isopod