Class Ostracoda(seed shrimp)

1. Goes through eight larval stages before becoming an adult.
2. Limbs can be withdrawn into carapace or shell.
3. Mobile caudal rami.
4. Diverse feeding habits.
5. Varied reproductive habits.

The organisms of the class Ostracoda are mainly aquatic animals, with a few terrestrial species found in the leaf litter of forest floors. These organisms have an egg shaped, bivalved carapace or shell. Their bodies are short and usually have two pairs of thoracic limbs. These organisms usually do not exceed 1/16th of an inch, the largest size reaching about the size of a cherry. Some Ostracods are filter feeders, while others feed on organic debris and some are even predators on other small animals. Reproduction is a varied process as well. The reproductive habit of the Ostracods can vary from some carrying their eggs inside the carapace valves to some other Ostracods that stick their eggs to the surface of aquatic plants at the waters edge.

• When the Ostracod becomes threatened by danger it can withdraw all of its limbs into the carpace. After the legs are completely withdrawn inside the carapace the Ostracod uses its adductor muscles to draw two valves tightly closed, completely protecting its limbs.
• A few Ostracods have the ability to live in a symbiotic relationship. For example, there are some species of Ostracods which live in the gills of crayfishes.
• An abundance of Ostracods, over 2,000 fossil species, have been found dating back to about 425 million years ago.

1. Bertin, Leon. 1967. Larousse Encyclopedia of Animal Life. London: The Hamlyn Publishing Group Limited.
2. Numerous Authors. 1982 Audubon Society Encyclopedia of Animal Life. New York: Crown Publishers.