|Ostracod grazing on filamentous green algae - Micrographia.com|
|Empty shell - Micrographia.com|
|Click to enlarge - Pionocypris vidua, - bumblebee.org|
Their flattened bodies lie within a bivalve structure similar to a mollusc. They swim with their legs extended but can contract them and close their "shell" to protect themselves. They lack a distinct abdomen and circulatory system but have antennae to seek out food (diatoms, bacteria and detritis) and mandibles and maxilla to obtain it. I will leave the anatomical details to Wikipedia.
Here are what 5th grade WOLF students would call "Fun Facts"* although some might be R-rated.
- Although fish eat ostracods, some may survive the passage through the gut. One study showed that 26% of those eaten by a bluegill passed out the rectum alive. Who counts these things?
- Many species reproduce parthenogenetically, i.e. without male fertilization, but some species have the largest sperm in the animal kingdom, up to 3.6 times longer that the adult's body.
- Ostracods are the most abundantly preserved arthropod in the fossil record (500 million years) and boast the oldest known example of a fossilized penis, 425 million years ago.
- Some species are bioluminescent, a defense mechanism seen in this video. During WWII, Japanese troops collected and dried specimens, then rehydrated them to provide a dim light for map reading without giving away their location.
* Amazing Facts about Ostracods.