Despite the diversity of single-celled, more complex organisms are much better known to man.They represent the largest group, which includes more than half a million species.All multicellular organisms have certain common characteristics, but at the same time very different.Therefore, it should be considered a separate kingdom, and in the case of animals - and classes.
General properties
main feature separating unicellular and multicellular organisms, is a functional difference.It arose in the course of evolution.As a result, the cells began to specialize in complex body, combining the tissue.The simplest is to use only one of all the necessary functions.This traditional plants and fungi accounted for separately as animal and plant cells also have significant differences.But they, too, should be taken into account in the study of the topic.In contrast to the simple, they are always composed of a plurality of cells, many of which have their own function.
Class mammals
course, best known multicellular organisms - animals.Of these, in turn, are allocated mammals.This highly organized class of chordates, which includes four and a half thousand species.Its representatives met in any environment - on land, in the soil, in fresh and salt water in the air.Advantages of multicellular organisms of this type over the other in a complex device body.It is divided into head, neck and torso, a pair of front and hind legs and tail.Due to the special position of the feet the body is raised above the ground, allowing the speed of movement.All of them are reasonably thick and elastic skin accommodating the sweat, greasy, fragrant and breast cancer.Animals have a large skull and complex musculature.There phrenic special partition called the diaphragm.Peculiar animal modes of transportation include various activities - from walking to climbing.The heart has four chambers and arterial blood supplying all organs and tissues.To use breathing lungs, to highlight - the kidneys.The brain consists of five departments with multiple cerebral hemispheres and cerebellum.
Class birds
Asked what organisms - multicellular, and not to mention the birds.This highly organized warm-blooded creatures, capable of flying.There are more than nine thousand of modern species.The value of a multicellular organism such class extremely large, so they are maximally extended and thus, participate in economic activities of the people and play an important role in nature.From the other creatures of birds distinguished by a few basic properties.They have streamlined the body with the front limbs, transformed into wings, and back, which are used as a support.Birds distinguishes dry skin without iron, with horn formations, known as feathers.Skeleton thin and durable, with air cavities that provide its lightness.The muscular system provides the ability to walking, running, jumping, swimming, climbing and the two types of flight - soaring and flapping.Most species are able to travel long distances.Birds have no teeth and is there a goiter, and muscle department, grind food.The structure of the language and the beak depends on the specialization of food.
Class reptiles
worth mentioning that type of creatures, representing multicellular organisms.Animals in this class were the first terrestrial vertebrates.At the moment, there are about six thousand species.Reptile skin is dry and devoid of glands, it covers the horny layer, occasionally coming down during molting.Durable ossified skeleton differs reinforced shoulder and pelvic girdle, and developed the ribs and chest.The digestive tract is long enough and clearly differentiated, the food is captured with the help of jaws with sharp teeth.Respiratory represented easily with a large surface area, bronchi and trachea.The heart is divided into three chambers.The body temperature is determined by the habitat.Excretory organs are the kidneys and bladder.Fertilization is internal, eggs are laid on the ground and protected by a leathery or skorlupovoy shell.
class amphibious
Enumerating multicellular organisms, it is worth mentioning, and amphibians.This group of animals is widespread, particularly common in warm and humid climate.They have mastered the terrestrial environment, but have a direct link with the water.There were amphibians from Crossopterygii.The body features a flat shape amphibians and separation of the head, torso, and two pairs of limbs with five fingers.Some also have a tail.The thin skin of different lots of mucous glands.The skeleton is composed of a plurality of cartilage.Muscles allow you to do a variety of movements.Amphibians are predators, food is digested stomach.Respiratory organs are the skin and lungs.The larvae are gills.Three-chambered heart with two circulation - such a system are often different multicellular organisms.To select using the kidneys.Fertilization is external, takes place in water, the development of a metamorphosis takes place.
class insects
unicellular and multicellular organisms, not least also differ a surprising variety.This type includes, and insects.It is the most numerous class - it includes more than one million species.Insect distinguishes the ability to fly and great mobility, which is provided with a muscular jointed limbs.The body covers chitinous cuticle, the outer layer of which contains fatty substances that protect the body from the withers, and UV damage.Other mouthparts reduce competition types, allowing you to always maintain a high number of individuals.The small sizes are an added advantage for survival, as well as a wide range of methods of reproduction - parthenogenetic, bisexual, larval.Some also differ polyembryony.Respiratory provide intensive gas exchange, and the nervous system with perfect senses creates complex behaviors due to instincts.
plant kingdom
course, animals are most common.But it is worth mentioning other multicellular organisms - plants.They were there about three hundred and fifty thousand species.They differ from other organisms is the ability to carry out photosynthesis.Plants serve as food for many other organisms.These cells have rigid walls of cellulose and internally contained chlorophyll.Most are unable to perform active movements.Lower plants are not separating the leaves, stem and root.Green algae live in water and can be different from the structure and methods of reproduction.Brown carry out photosynthesis using fucoxanthin.Red algae are found even at a depth of 200 meters.Lichens - following subkingdom.They are the most important in soil formation and used in medicine, cosmetics and chemical industries.Higher plants are distinguished by the presence of leaves, roots and stems.The most primitive - mosses.Most developed - trees, which can be flowering, di- or monocots and conifers.
kingdom fungi
should go to the latter type, which may be a multi-cellular organisms.Mushrooms combine features of both plants and animals.There are more than one hundred thousand species.A variety of cells of multicellular organisms manifested most clearly in the mushrooms - they are able to reproduce by spores, synthesize vitamins and keep still, but at the same time as the animals can eat heterotrophically not carry out photosynthesis and have chitin, which is also found in arthropods.
