In this article we will discuss about the aquatic and terrestrial habitats of animals.
Aquatic Habitats:
The animals which live in water are called aquatic animals. According to the nature of the water aquatic animals may be marine or fresh-water.
1. Marine Animals:
About three fourths of the earth’s surface is covered by the oceans. The salt water serves as the home for the marine animals who can survive neither in fresh water nor on land.
The sea beach is occupied by the littoral animals, some of which live on sand, others in mud, and still others remain attached to submerged rocks or to sea weeds. The depth of the ocean is inhabited by the abyssal or deep-sea animals which are collectively known as the benthos.
The open ocean is thickly populated by the surface-dwelling pelagic animals which either swim freely or float passively and are drifted from place to place by the high waves.
The pelagic fauna is thus subdivided into nekton, which includes the active swimmers, and plankton, which includes the smaller passive forms that are at the mercy of the currents. Marine animals are more or less restricted to their own respective zone either the sea beach, or the abyssal depth of the bottom, or the surface of the open sea.
2. Fresh-Water Animals:
Fresh-water animals are found in ponds, pools, rivers, lakes and swamps. Some prefer to live in stagnant water but others choose the running stream.
Each of these habitats may contain a number of communities, such as those occupying:
(1) The beach,
(2) The open water, and
(3) The bottom.
Terrestrial Habitats:
Terrestrial animals are those who live on the land. They may be simple surface dwellers or they may burrow beneath the soil and thus become sub terrestrial. The surface communities may choose to live on rocks, or plains, or desert or damp forest. The aerial animals spend a part of their time in the air, but they depend on the surface for rest. A number of animals are arboreal, homing amongst the branches of the tree.
Animal Associations:
Some animals habitually live upon or within other animals.
There are four main types of such animal associations:
(1) Commensalism,
(2) Mutualism,
(3) Symbiosis, and
(4) Parasitism.
These four categories are absolutely man-made, which are not discontinuous in nature but are diverse aspects of the same general laws. Commensalism indicates an association between two individuals which live together with no metabolic interdependence and the relationship is not necessarily continuous for the life of the partners.
Commensals may be external as well as internal. The best example of commensalism is the suckerfish Remora which develops a sucker for attaching to sharks. The Remora is thus carried from place to place and protected from enemies. They never injure their host and feed upon scraps that are rejected by the shark.
Mutualism involves an association between two animals in which there is a metabolic dependence, but it is not obligatory for existence. Association of hermit crab and a sea-anemone may be taken as example of mutualism.
Symbiosis indicates an association between two individuals in which there is metabolic dependence beneficial to both and both the partners are mutually benefited. In extreme cases, the two partners cannot live without each other. One of the best example of symbiosis is the association between termites and a kind of small flagellates which five within their digestive canal.
The termites feed on wood but are unable to digest the same; the flagellates help them by digesting the wood and thus save them from actual starvation. In return, the flagellates are safely housed, protected from enemies and supplied with food by their host.
Parasitism is an association between two individuals in which one is metabolically dependent on other and is benefited at its expense; the one benefited is the parasite. The host is always the losing partner. The protozoa causing malaria is a parasite; the host in this case is man. The parasites may live externally (ectoparasite) or internally (endoparasite).