what kind of species is the smallest one you mentioned?
Myxozoa is an unranked subphylum of aquatic, obligately parasitic cnidarian animals and contains the smallest animals ever known to have lived.
Animal
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.
what characteristics do all the organisms in the animal kingdom share Animals are eukaryotic, multicellular, heterotrophic, respire aerobically what is meant by the third feature? A heterotroph  is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. can you give example of such species? All animals and fungi, ome bacteria and protists, and many parasitic plants. regarding the first one; how are they classified? Insecta, Pisces, Amphibia, Aves, and Mammalia. which is the largest of it? The blue whale and the smallest? Myxobolus shekel what is the size of the largest one? length of 29.9 meters where are they found? In all major ocean basins, except the Bering Sea and the Arctic Ocean how fast do they swim? 20 to 48 km/h are they under any threat? Blue whales were nearly hunted to extinction in the 19th and 20th centuries by commercial whalers until the International Whaling Commission banned the taking of blue whales in 1967. The International Union for Conservation of Nature has listed blue whales as "endangered".
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Animal [SEP] Largest and smallest
The blue whale ("Balaenoptera musculus") is the largest animal that has ever lived, weighing up to at least 190 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 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.