What is Feeding Mechanisms in Physiology?
The feeding mechanisms depend on the nature of the food required as food can be obtained by the animals in different ways. Each and every mechanism for obtaining food is difficult to discuss in detail so that we will describes the basic principles below on which the different feeding mechanism operate in animal groups according to the type of food available.
Feeding on Small Particles:
The small particles can be taken directly by some microscopic algae and bacteria with the help of the digestive vacuoles. The most successful method of feeding on small particles such as detritus, living and dead plankton includes filter feeding or suspension feeding. In this method, the ciliated surfaces are used to produce currents and drawing drifting food particles into the mouth. In some animals, secretion of mucous is helpful as it traps the food particles.
In sponges, the flagella of the choanocytes, create internal water currents for trapping the food particles by phagocytosis. Both sessile and free living forms are filter feeders. Free swimming forms such as microcrustaceans, fishes like herring, menhaden etc. are selective filter feeders. Filter feeders are usually feed in water.
Feeding on Food Masses:
This type of method includes chewing and scraping used by many types of insects, invertebrates and herbivorous vertebrates to obtain food, while animals like earthworms ingest the medium in which they live and digest the organic material. The carnivorous animals like snakes normally grab and swallow their prey whole.
Chewing of food i.e. true mastication is seen only in mammals due to availability of teeth. Mammals have basically four types of teeth, which are incisors, canines, premolars and the molars. Incisors help in biting, cutting and stripping canines help in seizing and piercing premolars in crushing and the molars in crushing and grinding. The number and size of these teeth varies according to the type of food eaten.
Feeding on Liquids:
The organs are highly specialized in animals, which feed on liquids. These animals generally lack a digestive system of their own. The example includes parasitic protozoa such as tapeworms, flukes, endoparasites and aquatic invertebrates. They use their integument for taking up the nutrient molecules from the medium in which they live. Insects like mosquitoes, bedbugs, lice and leaches have well developed piercing and sucking organs. They use anticoagulant to prevent blood from clotting as it leaves the blood vessels ruptured by their piercing or rasping jaws.