In the biological world, animals are multicellular, eusocial, multifloral organisms in the Kingdom Animalia. With few exceptions, animals eat organic matter, breathe air, can move, can reproduction sexually, and are self-regulating when it comes to temperature. The animals that make up the animal kingdom eat food, breath oxygen, create sex, move to new locations, and are capable of sending and receiving mating signals.
The majority of animals today live for about one to five million years. This is because animals reproduce very slowly and a relatively small number of animals can survive for millions of years. Most animals reproduce only once a year, but a few animals can live for several years or a lifetime. Some animals reproduce very rapidly, however, such as insects which have lifecycle times of a couple of million years or more.
The majority of animals have a central body that they inhabit and that is where their brains and nervous system reside. Other animals have soft bodies with long, prehensile organs such as the beak or claws, which allow them to grasp and grab. Most animals have rear feet with two claws, but some have three claws; this enables them to climb. A few animals have wings, which they use to fly.
All animals have nerve tissue and brain cells, although most of this tissue is located inside the body and is surrounded by dense cell walls. The nerves and other tissues send and receive signals from the body’s organs and tissues. Brain cells are especially special because they contain memories, which are passed on to the animal cells and tissues and can be erased or destroyed when an animal is threatened or stressed. The nerves control the body’s functions by transmitting impulses from the cells to the muscle receptors. Neurons are covered with a thin cover of fatty tissues called myelin which is important in transmitting nerve signals.
Plants are animals’ primary food. Plants provide many of the nutrients and energy humans need. Animals also consume plant tissues, but these nutrients are not absorbed in the human form. Plants in the wild are eaten by animals and aquatic organisms, while many live in water or a soil bog. In nature, plant foods are rich in vitamins and minerals and carbohydrates.
Animals have evolved over time, but they are closely related to all other animals. All vertebrates are composed of multiple bones, teeth, muscles and organs. They have brains, nerves, and use the body for movement, but they have no vocal cords. The heart, lungs, stomach and liver are internal and contain organs, but they are attached to the bones with cords. Humans, chimpanzees, whales and dolphins are the only animal species that do not have a skeleton.