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OSTRACODA By Catherine, Brandon, & Nicole A.Characteristics - Class of Crustacea Known as seed or mussel shrimp Generally small (0.1 - 32 mm in length) Approximately 8,000 living species Very numerous in both marine and freshwater environments - Date back to the Cambrian period - Reveal detailed information on the history of our planet like climatic changes etc B. Difference from Regular Athropods Arthropod - exoskeleton - segmented body - jointed appendages Ostracod - laterally compressed bodies - undifferentiated head - molt carapace so lacking growth lines C. Body Plan - Shrimp-like organisms, encased in a bean shaped, bivalved shell (carapace) Typically have eight pairs of appendages - 5 head and 3 body the 2 valves are articulated by a dorsal ligament and closed by a single adductor muscle - carapace can be: be transparent (usually young) or opaque - elliptical, round, or rectangular 1. Sea Firefly (Vargula hilgendorfii) - only member of genus Vargula to inhabit Japanese waters - known in Japan as humi-hoturu - it is nocturnal and lives in the sand at the bottom of shallow water - at night, it feeds actively - known for its bioluminescence - predation defense or mating 2. Darwinula stevensoni - considered to be ancient asexuals, males are unknown wide geographical and ecological distribution - In Japan they are from lakes, ponds, rice fields, and spring run off. Female right lateral view shows the brood chamber towards the rear with three eggs. The right valve is larger than the left, and overlaps the left along the ventral margin when the carapace is closed. Most other genera have an opposite overlap. 3. Terrestricythere elisabethae - Can walk over dry surface by - taking a small supply of water with them, in and around their shells - special hairs on the shells help to retain the water and drag it along with them - if unable to replenish water before it evaporates they perish 4. Potamocypris humilis - eggs are tiny and can survive complete drying - The eggs and adults can hitch a lift on the feet of birds the long migrations of Arctic Terns explain the distribution of one species found in Northern Europe and South Africa 5. Cypridopsis vidua - Fish eat ostracods, sometimes in great numbers - Experiments show that 26% of specimens eaten by small bluegill sunfish came out the other end alive/unharmed - By tightly closing their shells and waiting they survived passage through the gut of the fish "Whoa! That was a journey I don't want to repeat!”