When you consider a person’s place in the animal kingdom, one’s level of consciousness can be compared to that of an animal. A cat is a very complex organism, but it is not a metamorphic animal because it does not undergo metamorphosis. Metamorphosis is a term used to describe changes in an animal that take place over the course of many years. Among the animals that undergo metamorphosis are birds, amphibians, fishes, mammals, reptiles, protozoa, fungi, algae, molds, and plants. Birds have the most complex life plan with nearly ten thousand species of birds alone.
Animals are multicellular, meaning that they are made up of more than one cell. Animals reproduce both asexually. Asexually, animals reproduce asexually by having sex and then letting it mate again. Animals have no need for sexual and reproductive processes such as reproduction and gestation. On the other hand, asexually, animals reproduce sexually by means of an ovulation process.
Sex and gender are the two main categories of animal science. Sexual classification refers to the distinction between male and female characteristics. The classification of sex in animals is largely based on physical features such as the presence of distinct lines of difference between the sexes. In terms of behavior, most animal species can be classified into two broad categories: hominids or simple cells and arboreal or semi-arboreal animals. Hominids are the Prototheria, which include a great number of the animal species we know today; arboreal species are those that are capable of walking upright.
Animals make up a diverse group of multicellular organisms. All animals possess digestive systems with a primary function of extracting food from a diet. Digestive systems also constitute part of the immune system in animals. Most animals have some form of tail, which serves as an aid to moving from one place to another. Other limbs are used in climbing, swimming, and walking.
Bacteria, prokaryotes, eukaryotes, and algae are the typical components of a living organism. A few protozoa, for example, belong to the class Protista, which also includes the single-celled algae. Among all the different animals, plants are the only ones that reproduce by means of asexual reproduction. Almost all animals reproduce through a process that involves the transfer of genetic material from an external source, such as an egg, to a more distant living being via a reproductive organ such as a leaf.
The primary distinction among animals is that vertebrates, meaning vertebrates and their nearest living relatives, reproduce by means of a process called sexual reproduction. These animals are different from asexual reproduction in that asexual reproduction involves no sexual contact between organisms. Sexual reproduction takes place when two organisms experience intercellular budding, where new genes are inserted into an existing gene pool. Animal genders are distinguished from each other on the basis of whether or not they are asexually reproducing. Animals with only a one-sex reproductive system are called monogenetic, while animals with both male and female sexes are classified as sexually complemental.