Aquatic ecology and Biodiversity

Unit 7- Biotic communities

7.2.1. Zooplankton
Zooplankton are heterotrophic plankton except bacteria and viruses. Their size range from 2 µm (flagellates) to several meters (jellyfish). Many of the zooplankton adapted to a pelagic mode of existence. Thus, they form a permanent entity called holoplankton. But the inshore (neritic) waters, a large part of the zooplankton consists of developmental stages of benthic organisms. Their larval forms which are present temporarily in the plankton are called meroplankton.The holoplankton includes animals such as foraminiferans, radiolarians, siphonophores, ctenophores, pelagic polychaetes, copepods, cladocerans euphausids, chaetognaths, pteropods, salps etc. Whereas meropkankton includes the drifting larval stages of numerous littoral and benthic species such as polychaetes, barnacles, decapods crustaceans, echinoderms , molluscs etc. Fish eggs and fish larvae are ichthyoplankton.