ostracode

Ostracodes are a diverse group of small crustaceans belonging to the class Branchiopoda, though sometimes they are placed in their own class, Ostracoda. They are commonly known as seed shrimp or mussel shrimp due to their small size and the presence of a bivalved carapace that encloses their body. This carapace is typically calcified and resembles a tiny clam shell. Ostracodes are found in virtually all aquatic environments, from marine to freshwater and even brackish waters, inhabiting a wide range of habitats including open water, sediments, and attached to vegetation.

The fossil record of ostracodes is extensive, stretching back to the Cambrian period. Their calcified shells are readily preserved, making them valuable index fossils for biostratigraphy and paleoceanography. The study of fossil ostracodes, known as ostracodology, provides insights into past environmental conditions such as salinity, temperature, and water depth. Modern ostracodes exhibit a remarkable diversity in morphology and lifestyle, with some being free-swimming while others are benthic, burrowing into the substrate. They are detritivores, filter feeders, or scavengers, playing roles in aquatic ecosystems as both prey and consumers. Their life cycles can vary, but many undergo direct development with several molts before reaching adulthood.