What on earth is a Giant Seed Shrimp?
Seed shrimp are crustaceans (related to shrimp, crabs, and lobsters). They belong to a group known as ostracods. There are roughly 8,000 extant (living) species. Ostracods have five paired appendages on their heads and one to three pairs of appendages on their bodies. Another common name for the group is “mussel shrimp” because they have a two part, hinged shell (known as a carapace) that envelopes their bodies…like a clam or a mussel.
Giant ostracods, Gigantocypris sp., are deep water seed shrimp. Members of this genus appear to be among the largest of ostracods on earth, reaching a total size of 32mm diameter. This one was the size of a green pea. The eyes of these crustaceans (“nauplius eyes”) are divided into two lobes and have reflectors built in. The eyes can detect bioluminescence from potential prey items, such as is produced by copepods. Prey items include copepods, mysids, chaetognaths, medusae and other small invertebrates – even very small fish. Gigantocypris store their eggs internally, in a brood pouch. The eggs develop there until they hatch (as miniatures of the adults). Juveniles are released into the pelagic environment. This individual is brooding purple eggs inside its carapace. Populations that have been studied are biased with 3 to 6 times more females than males. Roughly five species have been described inhabiting all of the world’s major oceans.