Amphibian
Amphibians are remarkable animals that include modern-day frogs, toads, caecilians, newts, and salamanders. These animals are the descendents of the first vertebrates to make the move from life in water to life on land. Despite their early colonization of terrestrial habitats, most lineages of amphibians have never fully severed their ties with aquatic habitats. A majority of amphibian species return to the water to breed and some species remain entirely aquatic throughout their entire life cycle. Most amphibians go through a complex metamorphosis process as they grow to adulthood.
Bird
Birds are bipedal, warm-blooded, egg-laying vertebrates characterized primarily by feathers, forelimbs modified as wings, and hollow bones.Birds range in size from the tiny hummingbirds to the huge Ostrich and Emu. Depending on taxonomic viewpoint, there are between about 8,800-9,800 living and about 120-130 extinct bird species in the world, making them the most diverse class of terrestrial vertebrates.
Bug
General term for any insect or similar creeping or crawling invertebrate.
Fish
Any of various mostly cold-blooded aquatic vertebrates usually having scales and breathing through gills; "the shark is a large fish"; "in the living room there was a tank of colorful fish".
Invertebrates
An invertebrate is an animal without a backbone. The group includes 95% of all animal species — all animals except those in the Chordate subphylum Vertebrata (fish, reptiles, amphibians, birds, and mammals).
Mammals
The mammals are the class of vertebrate animals primarily characterized by the presence of mammary glands, which in females produce milk for the nourishment of young; the presence of hair or fur; and which have endothermic or "warm-blooded" bodies. The brain regulates endothermic and circulatory systems, including a four-chambered heart. Mammals encompass more than 5,000 genera, distributed in 425 families and up to 46 orders, though this varies depending on the classification scheme adopted.
Prehistoric
Prehistory, more precisely, is the period from which no known written records (including later copies) have been preserved. When did prehistory begin? People disagree. If human prehistory is defined, as presumably it should be, as the pre-literate history of Homo sapiens then at least the matter can be resolved in principle.
Reptiles
The reptiles are a group of vertebrate animals.Reptiles were defined as the set of animals that includes crocodiles, alligators, tuataras, lizards, snakes, and turtles, grouped together as the class Reptilia.
