ANIMAL FORM AND FUNCTION

NUTRITION

     The basic aim of all the living organisms is “to stay alive”. And, for this, they require a steady supply of food or nutrients.

    Biologically, the body needs food and other nutrients mainly for providing the energy, which in turn is required for carrying out various cellular activities. However, there are numerous other functions, although minor, which are also served by nutrients.

   Living organisms can be classified into following categories on the basis of modes of nutrition:

(i)                  Autotrophs(“Auto”= self; “trophie”- nutrition ), i.e., self nutrition. It’s a mode of nutrition where an organism synthesizes its own food from simple inorganic materials like Co₂ and water (in presence of sunlight) for example, green plants.

(ii)                Heterotrophs (“Hetero” = others; “trophie = nutrition). They obtain their food from other organisms. These are consumers; e.g., animals. It can be following types:

(a)    Saprotrophs (“Sapro”= rotten). These organisms obtain their food from decaying, organic matter viz. dead plants and animals, e.g., fungi

(b)   Parasites These organisms derive their nutrition from another living organism, i.e., ‘host’.

    The animals are heterotrophs. Therefore, they depend upon plants to supply them with already synthesized organic compounds or several other sources to meet their diverse nutritional requirements.