1 The kidneys are used to remove excess water and ions from the blood. 2  These are then expelled as urine. 3  The kidneys perform a vital role in homeostatic regulation in mammals, removing excess water, salt, and urea from the blood.
Ectoparasites Parasites that live on the outside of the host, either on the skin or the outgrowths of the skin, are called ectoparasites. They are directly transmitted between hosts.
an organism that lives in association with, and at the expense of, another organism, the host, from which it obtains organic nutrition. Those that live on the outside of the host, such as ticks, are called ectoparasites, while others such as tapeworms that live inside the host are called endoparasites.