Like the common hermit crab, the female phronima is a squatter. This small, translucent crustacean does not occupy an existing shell. Instead, it makes a barrel-shaped dwelling from parts of gelatinous planktonic organisms.
Different species of phronima specialize in capturing siphonophores, salps, and jellyfish. Using sharp claws phronima cuts and eats its prey and recycles the gelatinous parts, cutting and assembling panels to fashion its own transparent barrel.
As it grows, the phronima builds bigger and bigger barrels. It clings to its house with clawed arms, swimming and feeding with bristle-covered posterior legs.
Unlike most crustaceans the female phronima takes great care of her progeny. She lays eggs, protects the embryos, and feeds her larvae inside the barrel. Phronima, in turn, are an important link in the food chain. Barrel and all, phronima are a real treat for fish.