on planet Earth there are infinitely many different kinds of animals.To understand them, it is necessary to examine the classification, which includes the types, classes and groups.Forms are the last step of division, because their number is so great.Better to take a few basic types of animals, which is much less.Learn their constituent species will be much more convenient.
Sponges
long time these animals were considered plants.Science has studied their structure recently.Type jaws includes a variety of animal species.Examples of these can be listed for a long time.The representatives are always live in water, but they differ in appearance very impressive way.Sponges may look like expressionless growths, cakes, twigs or lumps.Glass appearance of these animals looks incredibly beautiful and is a real masterpiece of nature - the so-called basket of Venus or sea orange seem delicate and translucent.They have common features - for example, sponges scarcely move.However, each species is able to produce food without problems - by passing through a body of impressive volumes of water, microorganisms of which is the ration of these bizarre creatures.But the interesting thing is that the coincidence of the names of these animals with the name of home accessories for washing or cleaning is not accidental: in the past for this purpose was used by living sponges that are beneficial for the skin and can be very tender to the touch.
Coelenterates
So, listing species, examples should be divided into categories according to their main types.Next - coelenterates lowly creatures whose bodies are composed of only two layers of cells.All types, with a few exceptions, are found in the aquatic environment.For example, this hydroid evdendrium, coral Acropora or siphonophores fizofora.Each of these types of unique appearance - some are like small trees, while others resemble feathers.What unites them wont to dwell in colonies and structure of the body - as is evident from the name, it is the only body cavity intestine.All types can be divided into two groups: the polyps, which are located at a certain location, or jellyfish which may be movable.
Worms
enumerating the types of animals, the list of which is very long, it is worth mentioning that type.Worms can be flat and ringed round.All these species are united structure of several cell layers - ectoderm, endoderm and mesoderm.The body cavity of worms there, the body is made up of parenchyma, which performs all necessary functions.However, there is a distinction between these types.Flatworms have a brain stem, near round there are few longitudinal and peripharyngeal nerve ring, and in ringed - abdominal nervous system.Moreover, the latter present a closed circulatory system, which is not in others.
Shellfish
worth exploring not only the primitive species.Classification includes much more advanced organisms, such as shellfish.This is the type that includes a maximum number of species.This organisms living in the sea (oysters, octopus, mussels, squid), freshwater (mussels, viviparus, mollusks) or wet ground (snails, slugs).The size of different species of mollusks are very different, they can be very tiny (a few millimeters) or as high as more than twenty meters in length.Many people lead a sedentary lifestyle, but some can move a reactive way.This squid and similar species.Classification of clams also includes options such as cephalopods, bivalves and gastropods.Some have a shell composed of several layers (stratum and lime), but many of its lost during evolution.It combines all of these species, the names of which, by the way, and include snails and squid, the structure of the digestive system.It consists of three divisions at the front, middle and hindgut.Some individuals are different muscular tongue with teeth, while others feed on passively, simply by filtering food from the water suspension gills.All kinds of circulatory system is not closed, and includes blood vessels and the heart with several atria and ventricles.Aquatic organisms breathe with gills, ground - light.The excretory system is represented by the kidneys, and nervous - nodes scattered with several large ganglia.
Arthropods
lists various types of animals, the list can not be complete without a mention of these organisms.Arthropods - it centipedes, and scorpions, and spiders, and crabs.Typically, this dvustoronnesimmetrichnye animals with a body divided into segments.The body is covered by the cuticle of chitin, which serves as an exoskeleton and protection for the body.Since this category includes a variety of animal species, examples of the respiratory system can be diametrically opposed - it is both light and gills.All representatives of non-closed circulatory system.The shape of the body can be varied.Normally, the body consists of several segments: the head, thorax and abdomen - they have these types of animals.Examples, however, include some variation of: spiders head and chest combined with the abdomen, while ticks segments are generally impossible.
chordal
most common and well-known species of animals, pictures of which everyone saw, are of this type.He is the highest and assumes the skeletal axis of the neural tube.Type consists of three main types of organisms: this tunicates, and vertebrates bescherepnyh.The first animal species, examples of which are much less known than the latter, more likely to live in an aqueous medium, and settle colonies.They Bursiform barrel or body, the nervous system of the ganglion and underdeveloped senses.These organisms include the following types: sea squirts, Appendicularia, pirosomy and others.These creatures reproduce in different ways, feed on algae, small animals, detritus.Interestingly, the adult form is simplified, but the larvae are much more active and highly developed senses.Bescherepnyh have separate heads, which determines their name.Breathe with gills and are not too many members, is considered the most famous lancelet.Finally, the vertebrates - the most famous and developed by a group of animals.They include all kinds of mammals, fish, birds, amphibians and reptiles.This type evolved in prehistoric times.At the moment, the man known around fifty thousand species of vertebrates.
