In this article we will discuss about the classification of marine organisms.
1. Plankton Community:
Plankton Community includes the groups of buoyant and floating marine plants and animals which live in the photic (euphotic zone or eupelagic zone) up to the depth of 200m from sea level. Plant planktons, called as phytoplanktons produce food through the process of photosynthesis with the help of sunlight, water and atmospheric carbon dioxide and thus they are primary producer green plants and are also called as autotrophs. Algae and diatoms are most important members of this community.
This community grows so quickly that within a short span of time they cover very large area of sea surface. Such area of dense cover of algae and diatoms is called marine pasture. There is reproduction explosion in some of the red-gray microscopic plants. Consequently, extensive area of red- gray plants is de veiled. Such area is called as red tide.
The size of zooplanktons ranges from one millimeter to several meters.
Zooplanktons are of three types:
1. Herbivore zooplanktons,
2. Carnivore zooplanktons, and
3. Detrivore zooplanktons.
In fact, zooplanktons act as a bridge between marine pastures of phytoplanktons of photic zone and the largest sea animals.
2. Nekton Community:
Nekton Community consists of swimming animals of various depth of the seas and oceans. Most of the animals of nekton group are vertebrates. Fishes of numerous species are most important members of this community. Sea fishes are divided into two groups viz. pelagic fishes and demersal fishes. These fishes are main sources of marine biological resources.
The swimmer marine mammais of nekton community are divided into two groups e.g.:
(i) Those marine animals which live in waters as well as on lands such as seals, and
(ii) The second category of swimming marine mammals includes those animals which spend their entire life in sea water such as whales.
Whales are divided into two families viz.:
1. Toothed whales, and
2. Whale bone whales.
Toothed whales are predators and range in size from smaller one (such as sperm whale) to giant size (such as killer whales). Dolphins and porpoises are also included in the toothed whale family.
Whalebone whale family of fishes includes blue whales and humpbacked whales. Sea cow such as manatees is also important species of swimming mammals of nekton community. Guano, mainly boobies and cormorants are important swimming birds.
3. Benthos Community:
Benthos Community includes all those plants, and animals which live on the sea bottoms right from the littoral marine biome to the open sea biome. The organisms of this community are characterized by large species diversity. The total known species of benthos animals represent 16 per cent of the total species of all the marine animals.
Benthos organisms are divided into two categories on the basis of their habitats e.g.:
1. epiflora and epifauna, and
2. inflora and infauna.
Epiflora and epifauna live on the surfaces of sea bottoms whereas infauna and inflora live in the detritus and are generally buried whether completely or partially in the ocean bottom deposits. Sea weeds, large algae, eelgrass and turtle grass are important benthos plants.
Benthos animals mostly include several species of molluscs e.g., bivale mussels, oysters and cockles. Majority of the benthos animals are scavangers (e.g., shark, sable fish, hagfish. octopus etc.). The life of marine benthic animals living on the 1000-4000m deep sea bottom largely depends on the organic matter of the upper surface of sea water and remains of nekton animals.