The five classes of vertebrates are fish, amphibians, reptiles, mammals and birds. These groupings predate modern genetics and represent functional groupings rather than true trees of phylogeny. Bony fish, for example, are more closely related to mammals than they are to sharks.Know More
Vertebrates are members of a sub-phylum within the phylum Chordata. The five vertebrate classes are grouped according to classical taxonomic lines rather than by clade, which is a true representation of each group's real relationship with the other groups of chordates. A clade consists of all descendants of a common ancestor. Thus, mammals and birds are good clades, as each group is descended from its own common ancestor, which was not ancestral to any other non-mammal or non-bird. Reptiles are a grade, not a clade, as some reptiles are more closely related to birds than they are to other reptiles. The same is true of amphibians, who are also not a true clade, as some descendants of their common ancestors are now reptiles, birds or mammals.
The four classes of air-breathing vertebrates are called tetrapods, and they have close relatives among bony fish. Tetrapods and bony fish are a good clade, as they are all exactly equally distant from the vertebrate outgroup of cartilaginous fish.Learn more about Zoology
All mammals are vertebrates. A vertebrate is any living being with a backbone or a spine.Full Answer >
Mammals have characteristics in their cells and bodies that help classify them as mammals. All mammals are vertebrates, are endothermic, have hair on their bodies and produce milk in order to feed their young.Full Answer >
Hippopotamuses are mammals, while crocodiles are reptiles. Although both of these animals spend the majority of their lives in the water, each creature has characteristics that make them very different from one another, including significant physical differences and differences of habitat.Full Answer >
Fish are vertebrates and therefore have backbones. Fish are sometimes observed with curved backbones. This is attributed to a variety of factors, including lack of vitamin C, injury, birth defect, temperature change while in egg and parasites.Full Answer >