Animals are multicellular, euarchial, single-celled organisms in the Kingdom Animalia. With few exceptions, all animals breathe air, consume organic matter, can move, reproduce by a process called fertilization, and have a nervous system. The three major animal groups are bovine (all bovines, including cattle, pigs, horses, and deer), monotremian (all amphibians and reptile animals), and reptile (reptiles and all vertebrates).
All animals have complete metamorphosis, a process in which a living animal transforms into a more appropriate adult form through a series of changes that involve the development of organs, tissue, and skin layers. The skeletal system of an animal plays a key role in completing this process, as does the nervous system. The organs of the animal also undergo changes and recover to a new adult form. Although animals may appear very similar (i.e., both eyes, kidneys, lungs, etc. ), each animal possesses a unique system that is specific to its type and class.
One class of animals is commonly referred to as domesticated animals. Domestic animals are those that are kept for their purposes, that is, to provide food, shelter, and breeding environments. Domesticated animals include dogs, cats, rats, birds, lizards, sheep, pigs, poultry, and many other domesticated animals. A distinction should be made between types of domestic animal and different forms of animal husbandry. For example, bees may be kept for honey production, while cats may be kept as pets.
Other animals are classified as asexual reproduction systems. Examples are all forms of fungi, algae, protozoa, and bacteria. These animals reproduce both sexually and asexually. Sexual reproduction occurs through a process of fertilization, and asexually, animals reproduce by mating and dividing into a single generation per year.
Sexual reproduction is very important in the life of all animals. However, humans can engage in sexual reproduction by using their reproductive organs such as a penis or a spermatozoa. Sexual reproduction can be further classified into two forms: a prenatal gain or a postnatal gain. Prenatal gain refers to gaining an advantage before birth; postnatal gain happens at or after birth.
Insects are among the largest animals in the animal kingdom. They are among the most diverse animals in the entire world. Insects reproduce asexually by laying eggs, which then hatch and new life begins in their lives. While it is nearly impossible to determine the exact insect reproduction cycle, we can conclude that insects have both maternity and a reproduction phase. Insects are among the primary basis for modern agriculture, and scientists have been continuously making advancements in insect biology.