Excretion in Animals

EXCRETION

All the organisms (plants and animals) are made up of cells. These cells work all the time for sustaining the life of the organism. Most of the work of the cells is in the form of biochemical reactions which they carry out all the time. 

The major Excretory products of Animals are Nitrogenous compounds such as Ammonia, Urea and Uric acid, Bile pigments, Water and Small Amounts of other waste products.

Different animals have different arrangements (or organs) for excretion

Also Check – Excretion In Plants

Types of Excretory Systems and Organs in Animals

The protozoans, the single celled animals, lose waste matter by simple diffusion through the cell membrane into the surrounding water. Some excretion and osmoregulation occurs by way of contractile vacuoles. 

Also Check – Excretion in Human Beings

In Amoeba ( single celled organisms), the waste material carbon dioxide is removed by diffusion through the cell membrane, but nitrogenous wastes (like ammonia) and excess water are removed by the contractile vacuole.

Also Check – Nutrition in Amoeba

The Insects, Centipedes, Arachnids and Millipedes have Malpighian Tubules for excretion.

 In Earthworms, the excretion and osmoregulation occurs through tubular structures called Nephridia.  In addition to nephridia, the moist skin of earthworms also acts as an excretory organ.

Excretion in Aquatic animals – In Freshwater animals ammonia often diffuses across the skin of an animal – Gills are utilized for this process aquatic animals produce very dilute urine, and pump salts inward through gills.In Saltwater, the risk is that all of the water will diffuse out of fish due to concentration gradient Salt excreted across gills, very concentrated urine produced to conserve water.

The mollusks and vertebrates have kidneys for and osmoregulation. 

In Human beings, the microscopic thin tubules form nephrons, which function as excretory units. Millions of Nephrons are present in Kidney.