Biotic communities of a pond

The aquatic organisms may be classified into the following groups depending upon their sizes and habits:

1. Neuston: Neuston is the unattached organisms that live at the air water interface of an aquatic habitat. They are most abundant in freshwater habitats.

E.g., floating plants such as “duckweed” as many types of animals.

The latter may also be of two types viz.,

1.1. Epineuston: Epineuston is the animals spending their lives on top of the air water interface. E.g., water strider.

1.2. Hyponeuston: Hyponeuston is the animals spending most their time on the underside of the air water interface. E.g., diving beetles, back swimmers, etc. 

2. Plankton: Plankton are the free floating minute plant and animal organisms, that have feeble lacomotory organs and simply drift on the mercy of water currents.

According to their quality plankton may be classified as:

2.1. Phytoplankton: Phytoplankton consists of chlorophyll bearing organisms. Members of the phytoplankton are of great importance as they form the basic of food for all other forms of aquatic life, being the primary producers.

E.g., Diatoms, Volvox etc.

2.2. Zooplankton: Zooplankton consists of animal origin. All major animal phyla are represented in zooplankton, as adults, larvae or eggs; some are just visible to the naked eye but most cannot be seen without magnification.

E.g., Rotifers, Copepods, Ostracods etc.

3. Nekton: These include the animals which are relatively large and powerful pelagic organisms that actively swim through the water.

E.g., an insect, a tadpole, a fish etc.

4. Benthos: They include the organisms living at the bottom. Benthic may crawl, burrow, or remain attached to a substrate. E.g., Bacteria

Benthos may also be of two types viz.,

4.1. Benthic epifauna: Benthic epifauna is that which lives above the sediment water interface.

4.2. Benthic infauna: Benthic infauna is that which lives in the sediment.

References: Gupta, S.K., and Gupta, P.C., (2006), General and applied ichthyology.