The word animal is derived from the Greek word anilos, which means “creature being alive”. Animals are multicellular, social, multiregional, protostome organisms in the microbial kingdom Animalia. With the exception of fishes, all other animals are aquatic, breathe air, can move, reproduce sexually, and feed on a variety of foods. The four classes of animals are: the bony fish, which includes eels, hermit crabs, and snails; the bony fish and amphibians such as salamanders, newts, etc.
Insectivores eat vegetation and mites or insects, which belong to the Lepismatidae order. Preferring to eat live beings over plants, they have elongated bodies and sharp, narrow claws. Herbivores eat plant matter and some animals such as reptiles and birds also feed on meat. Although the majority of animals are carnivores, some few are considered omnivores; in fact, most lizards and snakes are herbivores.
Prototheria is the name for a class of animals which are placental, meaning that they give birth to their young in some other way than through a woman’s uterus. Other classification of prototheria are eutherians, which include all dinosaurs and small dinosaurs; metathers, which include the prehistoric creature called Pterychopetal, the first multiturial animal to evolve into a bird-like member of its own genus. Multituberculates are another class of animals that are not placental and belong to the Kingdom Eutheria. The modern day multicellular eukaryotic organisms belong to the Kingdom Protista, which is similar to the chordates.
All living creatures are categorized according to their specific type. The phylum of animals consists of more than 900 different classifications. Among these are the kingdoms with sharks being the only exception in this regard. The Kingdom Animalia also includes swimming and swimming animals such as fishes, snails, crabs and lobsters and the subkingdom includes birds, whose physical features are so complex that they can be classed as having a vertebrate nervous system. The classification of animals is further subdivided into the classes A to G. The order Proclastida comprises fishes and crustaceans and includes all crawling and flying animals.
Among vertebrates, whales, dolphins, turtles, hippos and trilobites belong to the Class C. The Class D includes eels, salamanders and lizards. The Class E includes amphibians and reptiles such as chiroptosis and hermit crabs. The Class F is comprised of mammals such as cats, dogs and porcupines and the Class G includes all dinosaurs, pre-cranial and marine animals. The Class H comprises fishes and amphibians and Class I includes all mammals with bony or scaly features and those with scales. The Class J includes all birds and whales. The Class K comprises reptiles, most of whom swim.
Among the reptiles, salamanders are the only true reptiles and have a sub-order allomorphology (the classification of reptiles that includes all reptile groups). Most amphibians are not true reptiles (e.g., all terrestrial mammals that do not have scales), but instead belong to the Kingdom Vertebrata, while turtles are true reptiles and belong to the Kingdom Metatheria. Certain classes or categories of both the Metatheria and the Vertebrata are found together in certain environments. The most common classes of reptiles are the iguanodon (e.g., Iguanas), mosasaurus (e.g., Cretaceous), pterygoid (e.g., Squamata), elasmosaurians (e.g., Diplodoces) and saurian (e.g., Saurischia). amphibians are classified into Classes A, B, C, D, F, G and L, and include all salamanders, chordates, leeches, caddisflies and lizards, salamander eggs and adults, cutworms, chameleons, cormorants and damselfly.