Aquatic ecology and Biodiversity

Unit 7- Biotic communities

7.4.1. Crustacean copepods
Amphipods
Amphipods are less abundant in pelagial, frequently found on siphonophores, medusae, ctenophores, slaps etc. Common genus is Cythere, Bairdia, Themisto etc.

Mysids
Mysids or opossum shrimp appear like decapods, shrimps, resembles Euphausids. They are mostly marine, widely distribution and total of 450 species have been identified. Mysids are omnivores feed on living and dead plants and animals. A few species are truly planktonic and often abundant around river mouths and brackish waters. Hyperiids, Gammarids and Caprellids are three major groups present in plankton. Neomysis, Boreomysis, Eucopia, Gnathophausia, Mesopodopsis etc.present in Indian waters.

Euphaussids: krill

Euphausids (Euphasia superb) form a major component of the zooplankton and form important in marine food chain. They are small shrimp like large species They form important food for varieties of fishes- herring, mackerel, copelin, salmon, sardines, herring, salmon, tuna etc. and also for seals, oceanic birds, tuna, whales etc..
Decapods

Lucifer hanseni

Decapods include most of the larger conspicuous crustaceans such as prawn, lobsters, hermit crabs and crabs and are generally benthic in the adult state. Most of them have pelagic larvae and some of these which are pelagic as adults are strong enough swimming to be classed as nekton rather than plankton, Lucifer is the genus highly modified for planktonic existence. Lucifer is an important genus present abundantly in the Indian seas.
Ichthioplankton
Mollusca: clams and snails produce ciliated trocophore larvae and shelled veliger larvae; ciliated velum serves for locomotion and food collection

Cirripedia: Barnacles produce nauplii, which turn to cypris

Echinodermata: sea urchins, starfish and sea cucumber produce pluteus larvae of different shapes , which turn into brachiolaria larvae (starfish); metamorphosis to adult.

Decapoda: shrimps and crabs produce zoëa larvae; they turn into megalopa larvae in crabs

Pisces: fish eggs and larvae referred to as ichthyoplankton; fish larvae retain part of the egg yolk in a sack below their body until mouth and stomach are fully developed