What does ostracod mean?
An ostracod is a tiny aquatic crustacean belonging to the class Ostracoda. Its body is enclosed within two hard, shell-like valves, giving it a compact appearance and the common name “seed shrimp.” Ostracods inhabit both fresh water and salt water and feed on microscopic organisms and detritus. Although they are usually difficult to see without magnification, their remains are abundant and well preserved in many sediments. Scientists therefore use fossil ostracods to study past environments, including changes in water temperature, salinity, and chemistry. The term is mainly used in biology, ecology, and paleontology, where the broader classification is more useful than the everyday name “seed shrimp.”
nounA small aquatic crustacean belonging to the class Ostracoda, characterized by a compact body enclosed within two hard shell-like valves. Ostracods occur in fresh water and salt water and are known from the fossil record.
- A small crustacean of the class Ostracoda, having a rounded body enclosed in two valves and inhabiting aquatic environments.
"The researcher studied tiny ostracods collected from the lake bed."
"Ostracods are so small that they can be difficult to distinguish from particles of sediment."
"Fossil ostracods in the rock layer provide clues about the water conditions in which it formed."
The regular plural adds -s: one ostracod, many ostracods.
"The sediment contained numerous ostracods."
Ostracods are minute, shell-bearing crustaceans whose preserved remains help scientists reconstruct ancient aquatic environments.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does ostracod come from?
The word derives from the scientific class name Ostracoda, which was formed from Greek ostrakon, meaning “shell” or “earthenware vessel,” together with a form based on Greek eidos, “form” or “shape.” The resemblance of ostracods to small, enclosed shells accounts for the connection. The related English words ostracism and ostracize also draw on Greek ostrakon, originally referring to a potsherd used in voting.
Related word forms
How ostracod is actually used
This is primarily a technical biological and paleontological term. In general writing, it is less common than the alternative “seed shrimp,” though ostracods are also referred to by this name in scientific and educational contexts.