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www.GOALias.blogspot.comPaheli wants to know whythese animals cannot chewfood properly at the time theytake it in?Boojho wants to know whywe cannot digest celluloselike the cattle do.partially digested and is called cud. Butlater the cud returns to the mouth insmall lumps and the animal chews it.This process is called rumination andthese animals are called ruminants.The grass is rich in cellulose, a typeof carbohydrate. Many animals,including humans, cannot digestcellulose.RumenRuminants have a large sac-likestructure between the small intestineand large intestine (Fig. 2.9). Thecellulose of the food is digested here bythe action of certain bacteria which arenot present in humans.So far you have learnt about animalswhich possess the digestive system. Butthere are many small organisms whichdo not have a mouth and a digestivesystem. Then, how do they acquire anddigest food? In the section below you willlearn another interesting way of foodintake.2.4 FEEDINGAND DIGESTIONINAMOEBAAmoeba is a microscopic single-celledorganism found in pond water. Amoebahas a cell membrane, a rounded, densenucleus and many small bubble-likevacuoles (Fig. 2.10) in its cytoplasm.Amoeba constantly changes its shapeand position. It pushes out one, ormore finger-like projections, calledpseudopodia or false feet for movementand capture of food.Amoeba feeds on some microscopicorganisms. When it senses food, itNucleusPseudopodiumFood particle(ingestion)StomachFig. 2.9 Digestive system of ruminantFood vacuoleFig. 2.10 AmoebaEgested waste18SCIENCE