Biology Animal Nutrition Notes NEET/AIIMS

Animal Nutrition

Nutrition is processed by which organisms take those substances which are required to the Energy, Growth and Maintenance of life

       Nutriology: Study of food and its use in the diet.

       The nutrition process is completed in 4 steps.

       (i) Ingestion                   (ii) Digestion                       

       (iii) Absorption (iv) Egestion

Types of Nutrition

       Autotroph (=self nourishing) synthesises its own food.

       Two types –

       Photosynthetic nutrition Nutrients are synthesized with the trapping of solar energy by chlorophyll. e.g. all green plants.

Chemosynthetic nutrition

Nutrients are synthesized by the breakdown of complex inorganic or organic molecules, which provide energy. E.g., Nitrifying bacteria– break ammonia into nitrite and nitrite into nitrate. Sulphur oxidizing bacteria – break hydrogen sulphide into sulphur. Iron bacteria – break ferrous into ferric ions.

       Heterotrophs (= feeding on others) include animals, fungi, proteins and monerans.

       Heterotrophic nutrition is of three types –

  • Saprotrophic (two types – saprophytic and saprozoic)
  • Holotropic
  • Mixotrophic

       Saprophytic – Organisms secrete enzymes, which digest the food. They then absorb fluid food through the body’s surface.

       Example – Bacteria and fungi.

       Saprozoic – Organisms absorbs fluid food available in the medium through the body surface. Example – Some parasitic protists, such as Trypanosoma, and some invertebrates such as tapeworm.

       Holotropic (= holozoic) organisms taking solid or fluid food through the mouth.

       Examples – Animals.

       Herbivorous – Feeding on plants. Examples – Rabbit, Cow.

       Carnivorous – feeding on animals. Example – Lion, Tiger.

       Omnivorous – feeding on both plants and animals. Example – Cockroach, Man.

       Mixotropic – Organisms, which are both autotrophic and saprotrophic.

       Example – Euglena

       Depending upon food, nutritionally an animal maybe –

       Detrivorous – Feeding on organic remains mixed with soil. Example – Earthworm.

       Scavengers – feeding on fruits. Example – Vulture.

       Frugivorous – Feeding on fruits. Example – Parrot.

       Sanguivorous – Feeding on blood. Example – Leech, Female Mosquito.

       Insectivorous – Feeding on insects. Example – Frog, wall Lizard.

       Soilivorus – Feeding on the soil. Example: Earthworm

       Eggivorous – Feeding on the egg. Example: Snake

       Piscivorous – feeding on fish. Example: Birds

       Larvivorous – Feeding on the larva. Example: Fish

       Folivorous – Feeding on a leaf. Example: Goat

       Graminivorous – Feeding on greens. Example: Rhodent.

       Cannibals – Feeding on other members of own species. Example – Many Snakes, Scorpion.

       Coprophagous – (=Pseudorumination) Example – Rabbit.

       Myrmecophagous feeding ants.

Digestive System

In includes the alimentary canal and digestive glands.

Alimentary Canal

       It includes mouth including vestibule (space between gums and lips) and oral cavity (including palate, tongue, teeth and salivary glands); pharynx, oesophagus, stomach and intestine.

       The mouth of Prawn is bounded in front by labrum (upper lip) behind by labium (lower lip) and on sides by mandibles (jaws) :      


  • It forms the roof of the buccal cavity.
  • The anterior part of the palate is the hard palate.
  • The hard palate has transverse ridges (= rugae). which helps in keeping the food in place during mastication.
  • Posterior part of the palate is smooth and fleshy, soft palate. It helps in swallowing the food.
  • Posteriorly, the mid-free end of the soft palate hangs down as a small, conical flap uvula.

The uvula is movable and can separate the upper nasal part of the pharynx (nasopharynx) from the lower oral part of the pharynx (= oropharynx) during swallowing of food.


  • It lies mainly in the buccal cavity and partly in the pharynx. It is a muscular and highly flexible organ. The tongue of the whale is not movable.
  • The tongue is forked in snake and acts as an additional organ of smell.
  • It is attached to the floor of the buccal cavity by a median fold of mucous membrane, frenulum of tongue (= frenulum linguae).
  • It has an inverted V-Shaped furrow, sulcus terminalis. At the angle of this furrow, there is a small pit, foramen caecum.
  • The upper surface of the tongue has a median groove.
  • Weber’s glands are present at the border of the tongue on either side posteriorly.


  • Papillae containing taste buds are numerous on the upper surface of the tongue.
  • Papillae are

Vallarta – Large, 8 to 10 in number and lie in an A-shaped row near the base of the tongue. Each vallate papillae is surrounded by a circular groove, the wall of which has taste buds.

  • Fungiform – Round and deep red. More numerous but smaller than the vallate papillae. These are located mainly at the tip and margin of the tongue. These also bear taste buds.
  • Filiform – Smallest and most numerous. They are conical, Keratinized and whitish. These are found mainly near the centre and most of the upper surface of the tongue.
  • Foliate – 4 to 5 leaf-like folds at each border of the tongue near the base. These bear numerous projections (these papillae are not developed in the human tongue).           

Dysphasia – difficulty in speaking.  Dysphagia – Difficulty in Swallowing

Taste Buds

  • Papillae have taste buds.
  • The sensation of sweetness, saltness, sourness, and bitterness is found in the human tongue.
  • The tip of the tongue has taste buds for sensing sweetness.
  • The base of the tongue has taste buds for sensing bitterness.
  • Postero-lateral area of the tongue has taste buds for sensing sourness.

       Antero-lateral area of the tongue has taste buds for sensing saltiness.