Animal including salt water, hydrothermal vents, fresh water, hot springs, swamps, forests, pastures, deserts, air, and the interiors of animals, plants, fungi and rocks. Animals are however not particularly heat tolerant; very few of them can survive at constant temperatures above . Only very few species of animals (mostly nematodes) inhabit the most extreme cold deserts of continental Antarctica. The blue whale ("Balaenoptera musculus") is the largest animal that has ever lived, weighing up to 190 metric tonnes and measuring up to long. The largest extant terrestrial animal is the African bush elephant ("Loxodonta africana"), weighing up to 12.25 tonnes and
Animal measuring up to long. The largest terrestrial animals that ever lived were titanosaur sauropod dinosaurs such as "Argentinosaurus", which may have weighed as much as 73 tonnes. Several animals are microscopic; some Myxozoa (obligate parasites within the Cnidaria) never grow larger than 20 µm, and one of the smallest species ("Myxobolus shekel") is no more than 8.5 µm when fully grown. The following table lists estimated numbers of described extant species for the animal groups with the largest numbers of species, along with their principal habitats (terrestrial, fresh water, and marine), and free-living or parasitic ways of life. Species estimates