In biology, all living organisms, and does exist on Earth, divided into four huge groups called kingdoms.This bacteria, plants, fungi and animals.Each realm includes a great variety of genera and species consisting of a large number of units.Amazing and a huge variety of wildlife.In turn, animals are divided into single-celled and multicellular, invertebrate and vertebrate organisms.A science dealing with the study of them is called zoology (biology section).
variety of animals: Classification
Invertebrates usually related worms, mollusks, echinoderms, crustaceans, arachnids and insects.These animals (yes, worms - animals too!) Have no inside or outside pronounced spine.Sometimes there chitinous shell that performs this role.For vertebrates include fish, amphibians, reptiles, birds, mammals (people refers to the last class, because it feeds its young with breast milk).
Invertebrates: Worms
A variety of wildlife can be a good present studying these creatures.This group includes more than 46 thousand species of organisms.Worms move with the help of elastic muscles, bending the body in different directions.They live in the seas, rivers, lakes, swamps, in the ground.Bright, well-known representative - earthworms.It lives in the soil, helping to loosen and enrich it.It is very important for all kinds of farm work.Many classes of useful worms.For example, the leeches.Their use in medicine.A marine worms are the constant food for commercial fish harvested by fishermen.Without them, some species of fish just would not be the food.However, there are many parasitic worms that exist at the expense of other organisms (parasites on them).Due to the lack of personal hygiene, such parasites can get into and inside the human body and live there for years.So now that you realize how important it is to follow the simple rules of hygiene: wash hands before eating, do not use dirty dishes, do not allow the presence of flies.By the way, worms inside the settling of other organisms emit harmful products of its life activity, gradually poisoning his master.The person becomes nervous, his everything annoying, he quickly tired and weakened, there is a constant intoxication, and you need to have a serious interference with the doctors, special means of removing animals from the whole human body.
Shellfish
A variety of animals and large shellfish.This group has more than 130,000 species.And they live almost everywhere, even in the trees.But most of them lives in the ocean at various depths.Some of them are hundreds of years old.Shellfish feed on both plants and small animals, and organic waste.Almost all of them are protected in the form of a shell (except, for example squid, which is also a clam, but he has the beginnings of the shell).People have long shellfish consumed as food.Some representatives of this group are even delicacies.
Echinoderms
This starfish (1,500 species), got its name because of the ray on the body (many of them five, but some even account for up to 50 pieces).Stars who live in the sea, vary in size and appearance.A characteristic feature of the starfish - the ability to regenerate (like lizards).If the animal's severed limbs, then in its place it grows a new speed.A detached from the beam, under favorable conditions develop new individual.Most starfish - predators.
Sea urchins (800 species) also belong to the echinoderms.The body is covered with urchins needles of various sizes.A long arm can reach up to 30 centimeters.Jerzy move with the help of needles.And some of them are very toxic, dangerous to other animals.
Crustaceans
body of these animals consists of armored segments: head, thorax and abdomen.Of course, settling on the abdomen and chest, allow cancers to move around the surface.Their eyes are made up of many small holes, and on his head there are several pairs of jaws.
Arachnids and insects
A variety of animals living in the world, and is well represented by these groups, which number more than 27 thousand species.These two groups are related.Only the six legs of insects and spiders - eight.Once all the insects have wings, even in infancy.Spiders wings are not available.Also, the structure of the body in different ways: in insects has a head, thorax and abdomen, and spiders - cephalothorax and abdomen.
Vertebrates
variety of animals living on our planet, it is easy to imagine studying vertebrate squad.This fish covered with scales.They are a great variety of species, among which are very old inhabiting the ocean from time immemorial (sharks, fish crossopterygian).This amphibians and reptiles, birds, and mammals that inhabit the world.The variety of animals is so great that even an experienced zoologist not give a precise answer to the question of how many species exist in nature.Because there is no definitive answer: constantly open up new, some existing species disappear.Implemented by the cycle of nature, including the infinite variety of animals (see above photo).
