Ostracods

Ostracoda

Classification

Phylum: Arthropoda
Subphylum: Crustacea
Class: Ostracoda

Pronunciation

How to pronounce Ostracoda: //ˌɒstrəˈkoʊdə//

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Summary

Ostracoda, commonly known as seed shrimp, is a class of small crustaceans characterized by their bivalved carapace and diverse ecological roles in aquatic habitats. They are recognized for their extensive fossil record and unique reproductive behaviors, including some species displaying bioluminescence.

Physical Characteristics

Usually under 3 mm; bivalved carapace resembling tiny clams with legs; flattened from side to side; body generally encased in a chitinous shell that may contain calcium carbonate.

Identification Tips

Look for the bivalved carapace and small size (typically around 1 mm, varying from 0.2 to 30 mm); some species are bioluminescent.

Habitat

Aquatic habitats such as vernal pools, marine environments, and freshwater bodies; can be found in sulfidic caves and extreme environments.

Distribution

Marine and non-marine species found globally; deep ocean species documented at 9,307 m depth; significant diversity in temporary and extreme aquatic habitats, particularly in Africa and Australia.

Diet

Diverse; includes herbivores, carnivores, filter feeders, scavengers, and predominantly deposit feeders.

Life Cycle

Eggs can remain dormant during desiccation; they hatch as juveniles with bivalved carapace; undergo a series of molts to reach sexual maturity, which occurs after a variable number of instars.

Reproduction

Mating involves swarming; species may be sexual or parthenogenetic; brood care present in some orders; eggs glued to surfaces or as resting eggs in some species.

Predators

Species are preyed upon by various fauna, including amphibians and marine animals like whale sharks; certain clams utilize suction feeding to capture ostracods.

Ecosystem Role

Ostracods play significant roles in benthic ecosystems and as part of the zooplankton; they are important in biozonation and paleoenvironments studies.

Cultural Significance

Bioluminescent species were harvested in WWII by the Japanese army for illumination purposes during nighttime operations.

Collecting Methods

Sampling sediment from aquatic environments
Using plankton nets

Preservation Methods

Fixation in formaldehyde
Preserved in ethanol

Evolution

Class Ostracoda may not be monophyletic; however, some molecular and morphological studies suggest it is monophyletic although support for this is low.