Sponges: Porifera

Physical characteristics: The shape of bird's nest sponges ranges from tall and narrow, like a barrel, to short and wide, like a cake. These sponges grow to a height of about 10 inches (25 centimeters) and a width of about 8 inches (20 centimeters). The thick, hollow body tapers to a single sharp-edged upper opening. Short thin, hairlike silica spicules surround the opening and stick out of the upper third of body. Longer spicules cover the lower third of the body and anchor the sponge in soft mud. The spicules on the middle third of the body are arranged in a pattern that looks like the interlocking twigs of a bird's nest. Bird's nest sponges are white.

Geographic range: Bird's nest sponges live in the northeastern part of the Atlantic Ocean from Iceland to northern Africa, including the Mediterranean Sea.

Scientists are trying to find out why there are so many bird's nest sponges in the deep ocean, where there are usually very few of any animal. (Illustration by Emily Damstra. Reproduced by permission.)

Habitat: Bird's nest sponges live on soft, muddy bottoms in the very deep ocean.

Diet: Bird's nest sponges are probably filter feeders.

Behavior and reproduction: Scientists do not know how bird's nest sponges behave or reproduce.

Bird's nest sponges and people: Scientists are trying to find out why there are so many bird's nest sponges in the deep ocean, where there are usually very few of any animal.

Conservation status: Bird's nest sponges are not threatened or endangered. ∎