Crustaceans have a full toolkit for feeding. On the front of a crustacean’s head are two pairs of sensitive antennae for feeling food. Picture a lobster’s long antennae swinging up and down. Two appendages, often claws, are used to seize food and break it up into pieces. Crustaceans typically have three pairs of biting mouthparts for chewing. The configuration of their mouthparts varies, depending on whether they are predators, scavengers, or filter feeders. While crustaceans have many adaptations for eating, they are also a common prey for other organisms. Humans eat millions of tons of crabs, lobsters, and shrimp every year. Tiny crustaceans, including krill and copepods, are part of the plankton that tend to congregate in the top few hundred meters of the ocean and are are vital to the marine food web. As krill and copepods feed, they concentrate ocean nutrients into their bodies, which then become available to the fish and filter-feeding organisms that prey on them.