Mystacocarids: Mystacocarida

Physical characteristics: Adults measure less than 0.039 inches (1 millimeter) in length. This species is distinguished by very small differences in the size and shape of their body structures. They also have grooves on the body with edges that resemble teeth. The mouthparts are bristly, and the bladelike structures on the tip of the abdomen are short.

Geographic range: Derocheilocaris typicus (abbreviated as D. typicus) lives along the Atlantic coast of the United States, from Cape Cod south to southern Florida.

Habitat: This species lives deeply buried in beach sand. They are sometimes found several feet (meters) inland, but still within the zone where the tides keep the sand wet.

Derocheilocaris typicus use their antennae to crawl between sand grains. (Illustration by Jonathan Higgins. Reproduced by permission.)

Diet: They eat small bits of algae and bacteria between or living on the surfaces of sand grains.

Behavior and reproduction: They use their antennae to crawl between sand grains.

Eggs are laid in the sand. The larvae go through seven stages before reaching adulthood. Adults molt once.

Derocheilocaris typicus and people: This was the first mystacocarid ever to be discovered, resulting in the creation of a new order and subclass of crustaceans.

Conservation status: D. typicus is not considered endangered or threatened. ∎