Excretion In  Animal

To give out nitrogenous waste products after oxidation of food is excretion.

EXCRETORY MATERIALS -

1.      AMMONIA - Animals are amonotelic. It is aquatic adaptation. e.g. Protozoa, porifera, coelenterata, some polychaetes (Nereis), some crustacean (crab), some mollusca (Aplysia, sepia, octopus), fresh water teleost, tadpole larva of frog, aquatic tortoise.

2.      UREA - Ureotelic. Terestrial adaptation. Less poisonous than ammonia. e.g. some annelids (earthworm), some gastropods (Pila), elasmobranchi, adult amphibian, mammals.

3.      URIC ACID - Uricotelic. Its' chemical name is 2,6,8 trioxy purine. Last product of nucleic acid metabolism.

Xerophytic adaptation. Less poisonous, synthesized in liver. Eg. Insects, snails, reptiles, aves, desert mammals, camal.

4.      AMINO ACIDS - Aminotelic. In man 1.5 gms amino acids per day are excreted. e.g. unio, limnea, some echinoderms.

5.      CREATINE - Chemically it is methyl guanidoacetic acid. Stored in heart, testes, brain & uterus max. in striped muscles. More in urine of children & pragnent ladies. Arginine, glycine & methionine are essential for its synthesis. When creatin present in urine it is creatine urea. Anhydrous product of creatine is creatinine.

6.      AMINO ACIDS CONJUGATION - In mammals benzoic acid is fused with glycin amino acid to form hipparic acid. Also known as benzoglycine. In aves benzoic acid combines with ornithine to form ornithuric acid.

7.      TRIMETHYL AMINO OXIDE (TMO) - In some marine teleost.

8.      GUANINE - In spiders.

9.      HYPOXANTHINE & XANTHINE - In columba.

10.     MINERAL IONS - Na, K, Ca, Mg, Cl, are excreted. In sea birds and reptiles salt glands present to control mineral excretion. Marine fishes excrete minerals through gills. Marine fishes face great problem of water.