Zoology sponge. Sponge Type

Including about 10,000 known species inhabiting on Earth these days. Members of this type of animals are limestone sponges, ordinary sponges, six best sponges. Adult sponges are settled animals that live, attaching to rocky surfaces, sinks, or other underwater objectsAnd the larvae are in free swimming. Most sponges live in a marine environment, but several species can be met in freshwater reservoirs.

Description

Sponges are primitive multicellular animals that do not have digestive, circulatory and nervous systems. They have no organs and cells do not organize a clearly defined structure.

There are three main class of sponges. Glass sponges have a skeleton, which consists of fragile, glassy needles formed from silica. Ordinary sponges are often brightly painted and grow larger than the rest of the sponges. On ordinary sponges accounts for more than 90 percent of all modern types of sponges. Lime sponges are the only class of sponges with a spikel consisting of calcium carbonate. Lime sponges, usually less than other representatives of the type.

The body of the sponge as a bag perforated with a plurality of fine holes or pores. Body walls consist of three layers:

• outer layer of flat cells of the epidermis;
• the middle layer, which consists of a centered substance and amoeboid cells migrating within the layer;
• inner layer, formed from flagella and collar (choanocites) cells.

Food

Sponges feed by filtering water. They suck water through the pores located over the entire wall of the body in the central cavity. The central cavity is lined with collar cells, which have a ring of a sucks surrounding a flavor. The burning movement creates a current holding the water flowing through the central cavity into the hole in the upper part of the sponge called to weaken. Since water passes through the collar cells, food is captured by rings. Further, food is digested in food or amoeboid cells in the middle layer of the wall.

The flow of water also provides constant oxygen supply and removes nitrogenous waste. Water comes out of a sponge through a large hole in the top of the body called we can cooled.

Classification

Sponges are divided into the following main taxonomic groups:

• Lime sponges (Calcarea);
• Ordinary sponges (Demospongiae);
• Six Blue Sponges, or Glass Sponges (Hexactinellida, Hyalospongia).

Multicellular organisms (Metazoa.) - These are organisms consisting of cell aggregate, whose groups specialize in performing certain functions, creating qualitatively new structures: tissues, organs, organ systems. In most cases, due to such specialization, individual cells cannot exist outside the body. The bite of multicellular has about the types of types. The organization of the structure and vital activity of multicellular animals is distinguished by many signs from the organization of unicellular.

■ due to the emergence of organs, is formed body cavity - space between organs that ensures their relationship. The cavity can be primary secondary and mixed.

■ Due to the complication of lifestyle is formed radial (radius) or bilateral (bilateral) symmetry, What gives the ground to divide the multicellular animals of radial transichny and two-bichetic animals.

■ With increasing food needs, effective means of movement arise that allow you to conduct active meals, leads to the appearance musculoskeletal system.

■ multicellular animals need much more food than unicellular, and therefore most animals move to nutrition solid organic food, which leads to digestive system.

■ In most organisms, the external coverings are impenetrable, so the metabolism between the body and the medium occurs through the limited portions of its surface, which leads to the occurrence respiratory system.

■ with increasing size appears circulatory system, Which will break blood thanks to the work of the heart or pulsating vessels.

■ Form selective systems To output exchange products

■ Regulatory systems arise - nervous and endocrine which coordinate the work of the whole organism.

■ In connection with the advent of the nervous system, new forms of irritability appear - reflexes.

■ The development of multicellular organisms from one cell is a long and complex process, in connection with which more complicated life cycleswhich will certainly include a number of stages: zygota - Egg - Larva (kid) - young animal - an adult animal - a semi-creation animal - an aging animal - the animal died.

General features of the structure and vital activity of sponge type representatives

Sponge - the multicellular two-layer radially or asymmetric animals, the body of which permeated pores. Type has about 5,000 species of freshwater and sea sponges. The overwhelming majority of these species inhabit the tropical and subtropical seas, where they are found at depths of up to 500 m. However, there are also deep-water forms among the sponges, which were found at a depth of 10,000 - 11,000 m (for example, sea Yershiks). In the Black Sea, 29 species live, in fresh water bodies of Ukraine - 10 species. Sponges belong to the most primitive multicellular organisms, since they are not clearly expressed in them to the fabrics and organs, although cells perform various functions. The main reasonwhich prevents the mass spread of sponges is the absence of an appropriate substrate. Most of the sponges can not live on the orstive day, since particles of the alien climb the pores, which leads to the death of the animal. The salinity and water mobility, temperature have a large influence on the distribution. SAME general features Sponges are: 1 ) the presence of pores in the walls of the body 2) lack of tissues and organs; 3.) the presence of a skeleton in the form of needles or fibers; four) regeneration well developed and etc.

With freshwater forms common sponge-bodiaga (Spongilla Lacustris), which lives on stony soils of reservoirs. Green color is due to the presence of algae cells in the protoplasm.

features of the structure

Body The multicellular, has stalking, bushy, cylindrical, funnel shape, but most often in the form of a bag or a glass. Sponges lead an attached lifestyle, so there is from their body from below the foundation To attach to the substrate, and from above - a hole ( mouth) who leads to and trivial (paragastralia) cavities. The walls of the body are permeated with a plurality of pore, through which water enters this body cavity. Body walls are formed from two cell layers: outdoor - pinacodermas and internal - hoanoderma. Between these layers there is a structural student - mesoglya which contains cells. Sizes of sponges - from a few millimeters to 1.5 m (sponge neptune Cup).

Sponge structure: 1 - mouth; 2 - Pinacoderma; 3 - Hoanoderma; four - it's time; 5 - Mesoglya; 6 - archeocyte; 7 - base; 8 - three-way branch; 9 - atrial cavity; 10 - Splikula; 11 - Amemobocytes; 12 - colecitis; 13 - purocyte; fourteen - pinaccitis

Variety of sponges cells and their functions

cells	Location	functions
Pinoccitis	Pinakoderma	Flat cells that form a coating epithelium
Porocytes	Pinakoderma	Cells with intracellular channel-time capable of cutting and opening or close it
hoanocytes	Hoanoderma	Cylindrical cells with a long flagella that create a water flow and are able to absorb nutritional particles and transmit them to the Mesogly
Colencites	mesoglya	Fixed Star Cells, which are connective tissue support elements
Sclerocytes	mesoglya	Cells from which skeletal formations of sponges are developing - Splikula
	mesoglya	Cells are connected to each other with processes and provide some sponge body reduction.
amebecites	mesoglya	Movable cells that carry out digestion of food and diversity of nutrients by body sponge
Archeocitis	mesoglya	Reserve cells that can turn into all other cells and give the beginning of sex cells

Features of the organization of sponges are reduced to three main types:

Ascon - The body with paragastromia cavity, which is lined with homeocytes (in limestone sponges)

sicone - body with thickened walls, in which the sections of the paragastral cavity are made, forming flagella pockets (in glass sponges)

leicon - body with thick walls, in which small flagella chambers are distinguished (in ordinary lips).

Covers. The body is covered with a flat epithelium formed by the pinococcitams.

Cavity The bodies are called paramarish And lined with homeocytes.

Features of life processes

Support Provided by a skeleton, it may be limestone (spikula with Saso3), silicon (spikula with SiO2) or horny (from collagen fibers and substances spongugin, which contains a significant amount of iodine).

Traffic. Adult sponges are not capable of active movement and lead an attached lifestyle. Some minor body reductions are carried out thanks to myocytes, which in this way can react to irritation. Amebecites are capable of moving inside the body thanks to the pseudoopod. Larvae of sponges, unlike adults that can vigorously move in water due to the agreed work of flavors, which in most cases almost completely cover the surface of the body.

Food In the lips is passive and is carried out using a continuous flow of water through the body. Thanks to the rhythmic work of flavors honociva The water comes into the pores, the cavity falls into the paramptast and through the mouths are displayed out. Weighted in water dead remnants of animals and plants, as well as microorganisms are enjoyed by homeocytes, are transmitted by amecomitas, where they are digested and packed by them all over the body.

Digestion U intracellular sponges. The interests of nutrient particles are by phagocytosis. Unpained residues are thrown into the body cavity and are output.

Transportation of substances Inside the body is carried out by amobocytes.

Breath It occurs the entire surface of the body. For breathing, dissolved oxygen dissolved in water, which is absorbed by all cells. Carbon dioxide Also excreted in a dissolved state.

Selection Imaginary remnants and exchange products occurs along with water through the mouths.

Regulation of processes It is carried out with the participation of cells that are able to shrink or perform movements - porocytiv, myocytes, and chowanocites. The integration of the processes at the level of the body is almost not developed.

Irritability. Sponges react very poorly even on the strongest irritation, and the transmission of them from one site to another is almost imperceptible. This testifies to the absence of the sponges of the nervous system.

Reproduction Canopy and sex. Miscellaneous reproduction is carried out by external and inland kilibration, fragmentation, longitudinal separation, etc. In the event of an external boring, a subsidiary is formed on maternal and contains, as a rule, all types of cells. In rare kidney forms, it is separated (for example, in sea orange), and in colonial - retains communication with the maternal organism. IN sponges-Bodhagi And in other freshwater sponges, except for external, there is an internal binding. In the second half of the summer, when the temperature of the water decreases with an archeocive, internal kidneys are formed - gemulas. For the winter, the body of Bodharya dies off, and the gemmos are lowered to the bottom and, protected by the shell, winter. In the spring of it develops a new sponge. As a result of fragmentation, the sponge body disintegrates into parts, each of which, under favorable conditions, gives the beginning of a new organism. Sexual reproduction occurs with the participation of Games, which are formed from the archeocive in the Mesoglye. Most of the sponges are hermaphrodites (sometimes separately). In the case of sexual reproduction, the ripe spermatozoa of one sponge leaves the mesoglya through the mouths and with the flow of water falls into the cavity of the other, where with the help of the amecitis is delivered to the mature egg.

Development indirect (with transformation). Crushing the zygotes and formation of the larvae occurs mainly inside the maternal organism. Larva, which has flavors, goes through the mouths in environment, attached to the substrate and turns into an adult sponge.

Regeneration well developed. Sponges are very high level Regeneration, which ensures the reproduction of a whole self-organism, even from the sickness of the sponge body. For sponges inherent and somatic embryogenesis - Formation, development of a new individual from body cells that are not adapted for reproduction. If you skip a sponge through a sieve, you can get a filtrate containing live individual cells. These cells retain livelihoods for several days and with the help of pseudoenia are actively moving and collected in groups. These groups in 6-7 days turn into small sponges.

Sponge (Spongia) is a type of invertebrate animals. Sponges occur, probably from colonial collar flames, forming a blind branch at the base of the phylogenetic tree of multicellular.

Sponges have arisen in the Precambria (approximately 1 million. 200 million years ago!, Those. These are very ancient organisms), the greatest heyday was reached in the Mesozoic.

Sponges are predominantly marine organisms, not many - freshwater. Externally sponges are even difficult to accept animals. They are not moving at all, while attaching to the substrate, and they do not react to irritation. Sponges more often colonial organisms, but meet single. To the touch sponge solid, tough. Freshwater Badyagi gray or greenish, but sea sponges are often brightly painted. Coloring depends on the presence of pigment cells. Many sponges have a specific not pleasant taste and smell, so they are not edible and nobody touches them.

Sponges are distinguished by an extremely primitive organization. Their body has no any symmetry, it formless. Inside a glasswall or bag-shaped body (height from a few mm to 1.5 m or more) a typical sponge is located paragastral cavityvertex ustov hole. There are no real bodies and tissues, but their body consists of a variety of cellular elements. Flat cells are located on the body surface - pinoccitis, from the inside the paragastral cavity linked flavored cells, or hoanocytes. Between the layer of pinoccocytes and the layer of chowanocytes lies the structure of the substance - mesoglyaContaining amosombites, collencites, scleroblasts and others. Cells. On the surface of the body of the sponge set poreleading in channelspenetrating body walls. Depending on the degree of development of the channel system, the localization of the homanocytes and the compositions of the flavored chambers are distinguished by 3 types of sponges structure: ascona., sicone and leicon.

Almost all lips have skeletonformed by silica or lime needles, Horn sponges, the skeleton consists of sponrug's protein substance.

Sponge vital activity is connected with continuous filling Through the body of water, which due to the beating of flavors of the set of homoenocytes comes into the pores and, having passed the system of channels, flavored chambers and a paragastral cavity, it turns out through the mouth. Food particles (deriters, simplest, diatoms, bacteria, etc.) come with water in a sponge, and the exchange products are removed. The seizure of food is made by homeocytes and cells of the channel walls.

Most of the sponges - hermaphrodites. The flickering larva is developing from the egg - parenchimula, or amphiblastula, which goes out, swims, then settles on the bottom and turns into a young sponge. In case of metamorphosis, the process of the so-called sponge is observed perversion germ listkov, in which the cells of the outer layer migrate inside, and the cells of the inner layer are on the surface. In addition, spontes are widespread binding and education gemmul - varieties of dust reproduction.

All sponges, as mentioned earlier, are water, predominantly sea colonial, less often solitary animals, leading a fixed lifestyle. They meet from the coastal zone and almost to the maximum depths of the ocean, are most diverse and numerous on the shelf (shelf - a gentle non-deep zone of the seabed). In the northern and Far Eastern seas of our country, over 300 species live, in the Black Sea - about 30 species, in the Caspian Sea - 1 type of sponges. In total, about 2500 species are currently described.

The type of sponge is divided into Grade 4. The classification of sponges is the structure of the skeleton.

Class 1. Ordinary Sponges (Demospongiae). These sponges have a skeleton formed by uniaxial or four-glacial silica needles. Channel leafoid type. Usually colonial, less often solitary forms, mainly sea forms. This largest class of modern sponges is represented by 2 detachments: crestorogovogovaya and four-melted sponges.

In the Slow-up sponges, the skeleton consists of flint uniaxial needles and organic matter - spongugin or from some spongy fibers forming a mesh, less frequently branched body support. These are mainly colonial forms that have a kind of cortical or pillow-shaped fours, unevenly crumpled lumps, plates or various types of tubular, funnel-shaped, stalking, bush and other formations, up to 0.5 m or more. Krenevogovskaya Sponges include famous for us Badyagi and several species Toilet sponges. Toilet lips are used for toilet, medical and technical purposes. The fishery of these sponges is developed in the Mediterranean and Red Seas, off the coast of about. Madagascar, Philippines, in Mexican Gulf and the Caribbean. The so-called is most appreciated Greek sponge (Euspongia officinalis).

Four-beam sponges body spherical, egg-shaped, glass-shaped, pillow, is usually up to 0.5 m. The skeleton is formed by flint, usually four-glav (hence the name) or their derivatives - uniaxial needles located in the body radially. Also colonial, less often solitary forms. Dwell predominantly to a depth of 400 m. Four-beam sponges include a family Drilling sponges, or clions. These sponges are able to do moves inside a lime substrate, leaving on its surface rounded holes with a diameter of about 1 mm. It is believed that the drilling mechanism is due to the simultaneous action of carbon dioxide, isolated by surface cells of drilling sponges, and contractile efforts of these cells. About 20 species, mainly on shallow water of the warm seas. In our country - 3 species, in Japanese, black, White and Barents seas. These sponges are dangerous pests of oyster cans.

Class 2. Lime sponges (Calcispongiae). The skeleton of these sponges is formed by three-, four-beam and uniaxial needles from calcium carbon dioxide. The body is often keg -ide or tubular. The only class of sponges in which sponges have all 3 types of channel system are marked. Lime sponges are small single (up to 7 cm height) or colonial organisms. Over 100 species are common exclusively in the seas of moderate latitudes, mainly in shallow water. Representatives Sicone, Sicandra, Leuqandra, Aszetta.

Class 3. Coral sponges (SCLEROSPONGIEE). Colonial sponges. Width of colonies up to 1 m, wound - 0.5 m. Known with mesozoic. The skeleton consists of the basal mass of aragonite or calcite and silica uniaxial needles. Live tissue is only a thin layer (about 1-2 mm thick) covers the surface of the coral sponges. Channel leafoid type. Total 10 species, inhabit the shallow water among the coral reefs of West Indies, the western parts of the Pacific and Indian Oceans, in the Mediterranean Sea and O. Madeira.

Class 4. Glass Sponges, or six high sponges (Hyalospongia, or Hexactinellida). Known with Cambria. The most diverse and numerous were in the chalome period of the Mesozoic era. Skeleton from silica six-needle needles (or their derivatives) with rays lying in three mutually perpendicular planes. Monsterly single, bag-shaped, tubular, glazing or barrel shapes, up to 1.5 m high. About 500 species. Oceanic organisms, dwelling usually at a depth of over 100 m. Glass sponges are very beautiful and used as decorations. For example, sponge basket Venus, Eurplectel, Halyonma.

Sponges are the most primitive and the most ancient of modern multicellular animals. Their ancestors were probably Parenchimells, which turned to habitat in the attached state at the bottom of the reservoirs. The sedentary lifestyle did not contribute to the complication of the organization of sponges. Most types of type are colonial forms, and only a small amount of sponges have retained a single lifestyle characteristic of their ancestors. It is known about 5,000 species of this type, of which only a small amount inhabs in fresh watersAnd the rest are marine animals.
The main features of the structure. The most primitive representatives of the type - single sponges - have a boalovidu shape (Fig. 22). The walls of their bodies consist of two layers of cells - outdoor and internal, divided stud mesoglyeya. The composition of the outer layer includes basically epithelial cells that perform the role of protective cover. In the inner layer there are very characteristic of sponges collar cells, or hoanocytes Named so because their front edge stretched into a transparent collar surrounding the base of the flavor (Fig. 22). There are non-specialized cells in Mesogle, the value of which will be mentioned on. The combination of cells in the body of sponges, as already noted, loose and they can be changed to a certain extent.

Sponge body walls are permeated with many small pores which lead to the cavity surrounded by the inner layer of cells and opening out the larger hole - oskumomom. The flavored cell flagels create a water current, which enters the pores into the mentioned cavity and comes out through the osalkulum. This cavity should not be considered an intestinal, it serves only for water passage and, unlike real intestinal, or garbage, cavities are called paragastral. In mesogly cells, skeletal formations of different chemical composition: Lime, flint, spongine (spongine - a substance close to a chemical structure to silk). Thanks to the skeleton, the sponge can grow up, and not spread through the substrate, which facilitates the movement of water through their body.
Vital activity. Irritability. Sponges are slowly and weakly responded to different irritation, since there are no nerve cells in their body. Traffic. There are no muscle cells in the body of sponges, with the exception of those that are sometimes developed around weak. Therefore, the body of sponges is almost unchanged, and the movement of water through their body is carried out, as mentioned above, only due to the beating of the flavors of the collar cells. In addition, some cells can move inside the body, like amcribes, i.e., releasing falcons.
Transfer of substances Provided, firstly, by constant water movement through a paragaretral cavity that delivers the inner layer of oxygen and carrying dissimilating products, secondly, diffuse method (penetration of dietary food, oxygen and other substances from the layer to the layer).
Breath. The preparation of oxygen is performed through the inner and outer surface of the body.
Selection Disimicing products also occurs through the body surface. In addition, these products can accopede in some cells (mainly in the mesogle), moving from a soluble state into insoluble and therefore ceasing to adversely affect the body.
Digestion. Food in the form of small organisms or their residues falls with water into a paragastral cavity and is captured by collar cells that are able to produce alcohols. Some cells of the outer layer can also be captured, as well as mesogly. Digestion, like the simplest, intracellular. The substances decomposed as a result of the digestion partially diffuse into other cells and are absorbed there, and partly assimilated on the spot.
Reproduction. The sponges are very common with a powerful reproduction, which is performed by different species Kindding. The formation of colonies occurs as a result of the fact that the kidneys remain on the parent organism. In addition, special kidneys are formed, which fall out of the parent's organism after his death and give rise to new organisms. Sponges are multiplied with sexually. Most of the representatives of this type are hermaphrodites, a minority - separate-use. Sex cells develop from undifferentiated mesogly cell cells, and microgamets, according to new data, can also be formed from collar cells. Sperm and spermatozoa go into the water and penetrate the body of other sponges, where the eggs are fertilized.
Development. The development of the zigotes occurs through the stage described above - Morula, Blastuly, Parenchimula and the sea sponges ends with the formation of plankton larvae floating with the help of outer cell flagella. The larvae floating in water and transferred by the currents contribute to the resettlement of these seating animals. There are no freshwater sponges of plankton larvae and they are distributed in other ways. When turning the larvae into adult seats, sponges occur perversion of the germinal layers: Outdoor flagellas migrate inside, and the cells of the inner layer are moving outward. Thanks to this process, a layer of collar cells surrounded, as explained above, a paragastral cavity, creating so important for the described animal current of water, bringing food and oxygen and removal of the decomposition of metabolism is formed.
Origin. The simplicity of the structure of sponges, the absence of the intestinal cavity, the completion of the embryonic development of the Parenchimulus stage confirms the opinion of most zoologists that these animals occurred from Parenhimell.

Sponges are the most low-organized asymmetric or radial-symmetrical multicellular animals (Table I, Fig. 57). The type of sponges includes about 5,000 species, the overwhelming majority of which dwells in the seas and oceans, freshwater species of a bit (sem. Spongillidae).

Systematic position - radiant or radial-modmetric. Latin RadiaLia.
A type SpongeLatin name Porifera or Spongia

Fig. 1. Various sponges:
A - Leucosolenia Coriacea; B - Sycon Raplianus: V - Colonia Verongia Aerophoba; G is a toilet sponge (Spongia officinalis): D - Freshwater Badyag Spongilla.

General characteristic of sponges

All sponges in an adult state of fixed, attached animals that do not have nevous cells, nor sense organs, nor musculatures, no oral hole. D.C Water with suspended food particles passes through the whole body of the animal. Water falls through numerous pores (Porifera means bearing pores) located on the outer surface of the body of sponges, into the system of pore channels and flagella chambers, or cavities, and outwards through the mouth, or oskloum.

Sponge are located on cellular level Organizations. This means that their body is a cluster of loosely located, in varying degrees Differentiated cells infollowing certain functions: coating, support, water, nutritious, etc. However, these cells still do not form real tissues and organs.

The sponges distinguish the following main types of cells:

1. Pinaccitis - flat polygonal, capable of cutting cells that linse the outer surface and pore sponge channels.
2. Collar cells, or chowanocytes, cylindrical or spherical shapes. They form flagella chambers, and in the most primitive single lime sponges wretched the inner (garbage) cavity. At the free end of the cell, converted inside a flame chamber, is a burning, surrounded by a cytoplasmic collar (Fig. 2). With the help of an electron microscope, it is found that the cheanocyte collar is formed by a wedge of 30-40 closely adjacent to each other with the thinnest plasma grows - the tental. Hoanocite flagelter departs from the basal taurus to which the crystal parabaznaya caller is attached (Fig. 2,IN). The same ultra-thin structure has both collar flavored (craspedomonadina), which indicates their phylogenetic proximity. It is believed that sponges and collar flagelves had a common ancestor. Hoanocites perform the water and nutritional function. The beating of their flavors creates a constant directional current of water in the body of the sponge, and the dietary particles, brought by water, are captured and digested by the homanocytes. The whole process of digestion in sponges passes intracellularly. Imaginary food residues from digestive vacuoles are thrown out with water current through oskulum.
3. Amemobocytes are large wandering cells, they carry out phagocytosis and participate in digestion of food, receiving surplus of food particles from homepoxites. Amemobocytes are constantly moving in the shapeless mass of the main substance of the sponge - Mesoglee, which fills the entire space between the sponge surface and the aquifer system. Mesoglya binds all types of cells mechanically and chemically, or humoraln
4. Collests are star cells in contact with their neighboring cells, they perform a reference function.
5. Scleroblasts and sionioblasts - large cells forming the elements of the skeleton of sponges - Splikula and sponginotefibers.
6. The archeocytes are not differentiated cells that can easily turn into any type cells serve as a cellular reserve.
7. Sex cells formed from archeocites provide sexual reproduction.

All the types of sponges cells are capable under some conditions to move into an amoeboid state and turn into a different type of cells. Even early-grained homeocytes, according to the latest data, are able to lose collars and flagellas, go deep into the mesoglya and turn into an amethocytes there. The sponge can be cut into small pieces and wipe through fine sieve (mill gas), while cells will be separated from each other. If you put the mass of the vessel on the bottom of the vessel, then the cells will slide and form groups, or aggregates, cells that will turn into small sponges in a few days. Such a high p e-ge, the union of sponges is explained by relatively weak differentiation of their cells and the absence of real tissues.

Sponges, as well as all multicellular, multiply in sexual path. The formation of genital cells - eggs and spermatozoa - occurs common for all multicellular method. In addition to sexual reproduction, the sponges are inherent in a powerful reproduction - by outdoor kinding or the formation of resting inland kidneys - gemmul.

Appearance and internal structure

Sponges are not at all like animals, they rather resemble plants. No wonder they are early XIX. in. Relevant to the collecting group of zoophytes seem to be intermediate between plants and animals. The shape of sponges is extremely diverse. Many of them form growths and crusts on the substrate, Karavai, Bliss. Many sponges have a cupid, bush, tubular, mushroom (Fig. 1,A B C; Table. I) form. The uncertainty of the body shape of many sponges depends on the fact that they form colonies consisting of many individuals. In the growth of the colony usually loses the individuality of the components of its individuals (Fig. 1,G, e). Separate individuals clearly distinguishable only in a few colonial sponges (Fig. 1,IN ; Table. I). Single sponges are relatively few. Usually they have a more correct form - vases, cup or barrel. Single sponges can be identified with radial multipath symmetry.

To the touch, the body of most sponges is rigid, which is explained by the presence of a solid skeleton - limestone, flint or creamy.

Dimensionssponges fluctuate from a few millimeters to 1-1.5m long and up to 2 m in diameter. Many sea species Brightly painted, more often in yellow, orange, red, purple-purple and brown tones. Coloring causes a variety of pigment cells present in the Mesogle. Some sponges are deprived of pigment and look white or grayish. Freshwater sponge badyagi Painted in brownish or green. The latter depends on the presence of symbiotic unicellular green algae -zoohlorell.

Most sponges have a sharp, unpleasant odor, which depends on the release of poisonous substances. Sponge body itself also possesses toxic propertieshaving, apparently, protective value and conditioning along with a solid skeleton of the failed sponges. It is assumed that the smell and toxicity of sponges are due to the accumulation of a significant amount of metabolic products in individual cells and in the mesogle of sponges.

Fig. 2. The structure of sponges:
And the incision through a part of the body wall of the sponge of asconoid type; 1 - Picky Capal; 2 - Pina Kocytes; 3 - star mesogly cells; 4 - scleroblast with a spitule formed inside the cell; 5 - egg cell; 6 - Archaezpt; 7 - Hoanocites; B - Hoanocyte; B - the ultra-thin structure of the Hoanocyte of the limestone sponge R.Sycon Raplianus); 1 core; 2 - plasma collar; 3 - Baszlx Taurus; 4 - parabaznaya Taurus.

Internal structure Sponges are easiest to study on single forms. At the same time distinguish three types of their organization: and with conoid, or ascona, synocoid, or blue, and leikoidoid, or leicon.

Most simply arranged very small single (at least young) lime sponges Leucosolenia Coriacea (Fig. 1,BUT; Fig. 3, a). Their radially symmetrical body looks like a vase. Thin body wall (about2 mm) Limits the central garbling, or atriral, sponge cavity. The latter is dressed from the inside with an almost solid layer of chowanocytes, forming a primitive loose flavoring epithelium, which indicates the infringement tissue formation in sponges. The outer dermal surface of the body is mainly covered with pinaccitis (Fig. 2, l) mixed with cells of other types. Numerous tubes are very numerous, connecting the outer surface of the sponge with a gastral cavity. Their intracellular. The lumen forms pores by which water enters the garbage cavity. There are numerous star collests between the dermal surface and a layer of joanocyte in the journalist substance, the scleroblasts with the numbers and the three-axis numbers formed by them, various forms of amoeboid cells - the amobocytes and archeocytes, spindle-shaped cuts - myocytes, etc.

Fig. 3. Different types of sponges structure:
A - asconoid; B - skeonoid; In - leiko); 1 - oskulum; 2 - pores; 3 - flagella chambers; 4 - bringing channels; 5 - enduring channels; 6 - Hoanocytes; 7 - Gastric cavity. Arrows show directions. water currents.

The continuous bias of the Hoanocyte flavors runs down the water from the garbage cavity through the outlet - oskulum - outward, and through the pores in the body of the sponge there are all new portions of water.

This type of organization is called Ascona, it is found in a small number of species of limestone sponges or in young sponges, the structure of which in an adult is complicated. Most of the sponges are harder.

The complication of the organization of sponges (type of Sacon) is observed in small lime sponges from the genus Sycon et al. (Fig. 1,B; 39, b). The wall of the body of these sponges is thickened, numerous cylindrical phenomenon of the atria cavity is formed. Hoanocites are located only in these phenomena, which are converted into flavored channels. The attitudinal cavity of the synoide sponge lifted only the Pina-Kocytes. Water enters through the intercellular pores into the narrow channels lined with pinococytes, then in the harness channels, and from there to the attitudinal cavity and excreted through the oskulum outward.

Most large single and colonial sponges have a further complication of the organization. At the same time, the harness canals are divided into small spherical flagella chambers, which lie in several layers inside an even more thickened wall of the body of the sponge. All flagemic chambers are associated with an external environment of a complex system of leading channels, and with atria cavity - a system of discharge channels. This most complex type of structure is called leycooid (Fig. 59,IN). A progressive increase in the number of small flagery chambers leads to a significant increase in their filtration capacity. So, in the small sponge of Leucandra Aspera, height 7cm and diameter 1 cm , 2,250,000 buccible chambers with a common surface 52.5 are calculated.cm 2, 81 000 and 5,200 reducing channels. During the day, such a sponge filters 22.5l water.

Many sponges are secondary formed protective dermal membranes, or a cortical layer covering the body of the sponge outside. Atrial cavity can be strongly shrinkable, differing slightly from the discharge channels, especially colonial shapes. In the latter, it is usually impossible to distinguish between individual individuals that are part of the colony. About their quantities can only be judged by the number of sponge oskloumov.

Food with sponges is carried out by homeocytes and amobocytes. Hoa-Nocites capture small food particles (deriters, bacteria, unicellular algae. etc.) short pseudopods that form somewhat below the collar. At the same time, typical digestive vacuoles are formed making circular motions In the cytoplasm of Hoa-Nocite. Imaginary food residues are thrown out of the vacuoles reduced in the sizes in the collar zone. Large homeocytes of lime sponges capture the dietary particles, and then transmit them to them by the ambitance, which digest them and spread the nutrient material on the body. Larger particles are phagocycated directly by the amecomies suitable to the walls of the channels.

Breathing and allocations in sponges are diffuse. Oxygen dissolved in water, which passes through the entire body of the sponge, is used by it for breathing (gas exchange). Liquid products of metabolism and excrement from digestive vacuoles of homeocyte and selfocytes come through the channel system into the attitudinal cavity, and from there with a current of water are thrown through the ousto.

So far, it is not found out how coordination between all the cell elements of the sponges is carried out. French scientists (TYUZ, Pavaz, Grass, etc.) described bipolar and multi-polar-eyed spine and bubble cells that form connections with other types of cells. They consider them for nervous cells forming diffuse nervous system. However, the sponges have an extremely low ability to react even to coarse external irritation (chemical, thermal, etc.). A sponge can be pierced with a hot metal rod, but the reaction to this irritation will spread through the body very slowly and for a slight distance. All movements of the adult sponge are reduced to slow closure and dyeing. All this gives the basis to most scientists to deny the presence of spontes both nervous and muscular system.

Skeleton

The overwhelming majority of sponges have a skeleton. Features in the structure and composition of skeletal entities are an essential systematic sign. The skeleton among various groups of sponges can be limestone, flint, crenevogovogovoy and horny, or spongin.

A lime skeleton is of its respectable small group exclusively marine, more often than single sponges (Leucosolenia, Sycon et al.). It is formed different in the form of needles, or by sprockets consisting of calcium carbon dioxide. Distinguish between one-, three- and four-beam needles (Fig. 4,BUT). At Sikon and other sponges (Fig. 57) they surround the flagella and oskulum, and the ends can hang out.

Fig. 4. Skeleton of various sponges:
A - Splitles of limestone sponges; B - silkules of glass sponges; In - Skeleton Badyagi; 1 - spongine fibers; 2- flint spls; G is a spongy skeleton of the toilet sponge.

The spicules are formed by special cells of mesoglyee - sclerob-stamps. The deposition of carbon dioxide and the beginning of the formation of a spicula occurs inside the scleroblast. When the spitule reaches the size greater than the sizes of the scleroblast, the latter dies, and the needle remains in the Mesogle.

The formation of three- and four-beam sp camery occurs when the joint activity of several scleroblasts forming single-headed spiculas, which are simultaneously soldered with their ends at a certain angle.

The flint skeleton is formed by the sprockets consisting of silica, which is located in the scleroblast around the axial thread. The latter consists of an organic matter.

Flove spakes are two births: larger - macrosclerites, which make up the basis of the skeleton, and small - microsclerites. The flint sproculas are very diverse in shape (Fig. 60,B). Macrosclerites can be single, three- and four-axis, reaching some of the lighter sponges. So, at the glass sponge Hyalonema (Fig. 63,B) The "root" threads have a length of several tens of centimeters, and the MONORHAPHIS sponge has a so-called axial spirule reaches length 3m.

The creamy skeleton is available at Badag and some other sponges (Fig. 4,IN ). It consists of flint spls and fibers formed by a special organic matter - spongin. Sprong is complex organicThe composition is close to silk containing iodine (up to 14%). Sponaggin fibers are not formed inside individual cells, but intercellularly. Small cells spongyoblasts as a case clothes growing fiber.

Horny, or spongin, skeleton, peculiar to a small number of sponges (toilet sponge), due to the reduction of flint sprocket consists only of spongugin (Fig. 60,D).

Some very small sponges are completely devoid of skeletal entrancements. Apparently, the loss of the mineral skeleton with horny and puzzling sponges occurred secondary.

Sponges are peculiar both for use and sexualScrogging set. Mascable reproduction of spongesand development walks in two ways: outdoor and inland kill.

Outdoor kidding is to form small swirling - kidney, then growing and forming their own oskloum. For most sponges, subsidiaries are not separated from the maternal, and a colony is formed. Single sponges have subsidiaries separated from the maternal and switch to independent existence.

Internal kinding is observed in freshwater badag and some sea sponges. Badgy in the fall, the archeocytes are collected in groups and a double chiantoid shell is formed around them. The outer layer of this shell has air chambers. Scleroblasts surrounding the inner kidney, or Gem Mu Li (Fig. 61), form special scurrities, so-called amphids, usually consisting of columns with star-shaped expansions at the ends. Amphids are located between two layers of the shell.

In the fall of Badag colony die, and viable gemmos are preserved inside them. They are well tolerated freezing and drying out the reservoir. Gemulas may remain on the site of the old colony or, when it is destroyed, transferred to the flow, wind or waterfowl. Thus, hemulas provide both the experience of sponges during the unfavorable time of the year and their settlement.

In spring, the archeocytes come out of the gemula and form a new sponge, and the contents of several gemmool often merge together and develops into one colony.

Fig. 5. Sponge gemulas:
A - Gemmula Lake Badgya (Spongilla Lacust-Ris); 1 - literal opening; 2 - Megasclers; 3 - microslings; B - incision through the gemula Badyagi Ephydatia Blembingia; 1 - amphids; 2 - internal cuticular sheath; 3 - literal opening; 4 - closing its partition; 5 - the inner mass of the cells.

Sexual speech is characteristic of all sponges. A significant part of the sponges is hermaphrodites, but many, including freshwater Badyagi, separate-use. Alone colonies form only egg cells, and others are only spermatozoa. Sex cells are formed in mesogle from archeocytes. Female sex cells - eggs, or oocytes, remain in Mesogle, where their fertilization occurs. Male sex cells - spermatozoa - go into water and penetrate with water current in neighboring colonies.

Fertilization in all sponges is very peculiar. The spermatozoa penetrates through the collar inside the homeocyte, where it loses the tail and incins. Such a spermatozooid chowanocyte passes into an amoeboid state and turns into a cage with a carrier. The latter migrates in Mesogly, where it is absorbed by the oocyte. At the same time, the haploid cores of the oocyte and spermatozoa merge, i.e., the process of fertilization occurs.

The crushing of the fertilized egg in the sponges is usually occurring inside the maternal organism, where the larvae is formed. The development of sponges is very diverse and sometimes quite difficult.

In some lime sponges (Sycon Raphanus), the crushing of the egg passes in a mesogle under the layer of homeocytes (Fig. 6,BUT). As a result, it is formed by Blastuly, in which eight large cells are closely adjacent to the homanocytes, and small, more numerous flagella cells make up its second part, located freely in the Mesogle. Farms of small cells are directed inside the cavity of Blastuly. Then, in the center of Blastuly, a group of large cells is lined up and a hole is formed through which rapidly multiply breeding flames are visible. The inner part of the larva with flavored cells is strifted in the form of a dome towards the layer of homeocytes, and large cells depart from homeocytes, are located at the edges of the opening, and then closed on the pole opposite to their original position, where previously were previously small cells. This process is called excursion or you wrapped the surfaces of the embryo. Such a change, or inversion, the surfaces of Blastuly in other multicellular is not observed. The simplest similar process is known only when the colonies of Volvox are forming. Large cells are pumped in addition to the formed amphiblastulars (Fig. 62,BUT). Then they again protruding, and the ball larva leaves the maternal organism. AMPI blastuly freely floats due to the beating of flavors located on its front pole, and the rear pole is formed by large grainy cells (Fig. 6, a).

Fig. 6. Development of sponges and their larvae:
A- development of Sycon Raphanus sponge; L - ampnblastula in the body of the maternal sponge (visible in violation of large cells); 2 - floating amphnblastula; 3 - flexigation of flicent cells; 4 - attached larva; B - the larva of the Mukhsha Cream Sponge.

After a short period of mobile existence, the amphnblastula is attached to the front pole to the bottom surface. At the same time, small flask cells are inserted inside the amphiblastul cavity, and large grainy form the outer layer, i.e. the process of the gast-rules occurs. Blastopor, which the larva attached to the substrate is closed, the flagellas lose the flagella (de differentiate) and reproduce sharply. Later, the choofocytes of flavored channels are formed, and the outer large grainy cells turn into all other sponge body cells (Fig. 6,BUT ).

In some ordinary sponges, for example, Oscarella Lobularis and others, a single-layer blastule has been developing in the maternal body, and the flags are evenly covered with flavors. She leaves the maternal sponge and swims freely. Its rear pole is formed by longer reddish cells, and the front pole cells are colorless. It then sits on the bottom of the front pole, the colorless cells of which are pushed inside, that is, typical gastruption occurs by invagination. Outdoor red cells are losing flagella, some of them disintegrate. Blastopor closes, and there is a complex process for the formation of flaky chambers due to the front-pole flagellas, all other parts of the body of the sponge (channel system, the outer surface and the atrial cavity, skeleton, etc.) are formed by reproduction and differentiation of the rear pole cells of the rear pole.

Part of ordinary sponges (Monaxonida, Keratosa), the mother's sponge leaves the more complexly organized larva - parenchymol (Fig. 62,B). Outside, it is almost entirely covered with flagella cells (some species in the rear pole there are no flavors), and inside it there are loose cells, which in individual species are capable of differentiate to the amobocytes and scleroblasts. Even before hatching the larvae from the maternal sponge, the formation of a speaker begins.

After a short period of free swimming, the parenchymal is attached to the front end to the bottom and is very compact. All flagellas migrate it inside the body (one or groups), where their flagellas disappear. Later, these cells turn into homeocytes and form flagella chambers. At the same time, the internal cells turn the entire outer surface of the sponge. A part of the internal cells of the mesoglyee sweeps the leading and discharge channels, the atria cavity that breaks through the oskulum. This method of the development of a sponge corresponds to the late gast-rules by multipolar immigration and epibolics of other multicellular.

In freshwater spongesbadgy (Spongilla Lacustris) There is still a large embryonicization of development. In the maternal sponge organism in a parenchum, the formation of not only selfocytes and sclerob stoves, but also flame cameras occurs. Such a parenchymal is more correct to consider the young sponge that has no canal system yet. It appears from the coil of the mother coated with flagella cells. After it is fixed on the soil of the water branch, flagellas migrate inside the mesogly, where they are phased by the amebecites.

Thus, in this case, the harness cells act as a temporary lacrimal organ of movement. Further development Such a sponge is reduced to the construction of the channel system, the dealer of the dermal surface, the atrial cavity, etc.

Some scientists consider the first phenomenon of large amphiblastules of lime sponges, passing in the maternal sponge, as an introduction gastration. Then the pouring of small flavored cells of its rear pole after the amphiblastulas sedimentation will be secondary, and not real gastroy. Accordingly, these scientists consider sponges with animals with twisted layers. In the development of ordinary sponges, surface harness cells parenchymal migrate inside and converted into digestive cells - choanocites. This, too, as it would confirm the chosening of the germinal layers of the body, in which they saw the indigenous difference in sponges from all other multicellular animals. A more detailed study of the embryonic development of sponges showed that in some forms described above, no turning of the layers occurs. Moreover, in freshwater sponges, surface and harness cells play the role of a provisional larvae of the movement and in building a body of an adult sponge of participation is not accepted.

Surface flames of lurisers of sponges can be viewed as a kin climb - a motor layer. When moving to a sedental lifestyle, it in an adult sponge goes inside and performs a water-melting function. Phagocitoblast is the inner layer - gives all types of sponges cells, both typical phagocytes and lining the boundary surfaces (outer dermal surface and channel system). Only in this sense can we talk about the perversion of the primary layers of the sponges. No ecto- and edoderma, i.e., real cover and digestive tissues, there are still no sponges as they do not have true germinal leaves. About the extremely low level of cellular integration indicates a variety of types of their individual development.

Fig.7. Glass Sponges: A - EuPiectella; B - Hyalonema.

Classification

The main feature on which the classification of sponges is based, is the structure of their skeleton. The type of sponges is divided into three classes: 1. Lime sponges (Calcarea); 2. Glass sponges (Hyalospongia); 3. Ordinary Sponges (Demospongia).

Class 1. Lime Sponges (Calcarea)

Lime sponges are exclusively marine small, often single forms. Their skeleton is formed by lime spikulas. This is usually the inhabitants of shallow towns: Leucosolenia, Sycon, Sycetta, Leuconia, etc. "(Fig. 1,A, b).

Class 2. Glass Sponges (Hyalospongia)

This class also includes sea, but deep-water sponges with a flint skeleton formed from the twin-axis spoolel (macrosclerites). They own Eupiectella (Fig. 7,A), Hyalonema (Fig. 7, b) With a bunch of long tail flies, which they are held in the orcrew soil, Monorhaphis, etc.

Class 3. Ordinary Sponges (Demospongia)

The most difficult (leycooid) sponges with a flint skeleton of four-axle or uniaxial macrosclerites, often fortified by spongin fibers. Ordinary sponges are most numerous and diverse. This class includes several detachments.

The skeleton of these sea sponges is formed exclusively four-axle sprockets. In the Barents Sea in large quantities GEODIA meets (Table I), forming large spherical colonies, up to 50cm in diameter. Some representatives of this detachment - Oscarella, Halisarca - deprived of a sprocket; They are called fleshy sponges.

Detach 2. Uniaxial Sponges (Monaxonida)

The skeleton of these sponges is formed by uniaxial silica spirits associated with a network of spongin fibers in a solid mass. Some species have little, and spongy fibers are greater.

The uniaxial is extremely diverse, they include both marine and freshwater species. Among the sea sponge is knownneptune Cup (Poterion Neptuni) that lives in Pacific Ocean and reaches 1.5m. Also, drilling sponges (CLIONA) are also interesting in limestones, on mollusc sinks and on coral polyps.

A large group of widespread freshwater sponges of Badag (Sez. Spongillidae) forms crusts or massive shapeless growths (Fig. 57,E) At the bottom of the reservoirs (on the stones, stems of aquatic plants, etc.), often painted in green or brown color. Baikal sponges (Table I) at small depths form bushy thickets to1 m high.

Detachment 3. Horn Sponges (Keratosa)

Ordinary sponges whose skeleton does not contain flint split, and only the network of spongin fibers is formed. Usually massive large forms:konarian sponge (HYPPOSPONGIA Communis), reaching 90cM in diameter, Verongia (Verongia, Fig. 57, B) and etc. The greatest value It hastoilet sponge (Spongia officinalis), the usual in the Mediterranean, which has long serves as a fishery (Fig. 57,D).

Phylogery sponges

Sponges - a very peculiar group of multicellular animals. In terms of organization, they occupy an intermediate position between the simplest and intestinal. The community of the ultra-thin structure of the lobster cells of sponges and collar flavored flashes Craspedomo-Imaadina says that they have occurred from one ancestor.

Being typical multicellular animals, sponges have some features of the simplest:

1. Hoanocites are located loosen, they can go into mesogly and move into an amoeboid form.

2. Many types of sponges cells have an amoeboid nature. So, female sex cells - oocytes - move using pseudoenia, get into the attitudinal cavity in search of nutrients and are used back.

3. In case of fertilization of the oocyte, a deepening is formed - cellular mouth; It captures incistended sperm as Ameba captures prey.

4. The process of inversion of surfaces, having a place in the development of AM-Fiblastule of lime sponges, is known only for the simplest (Volvoci-DAE). The latter does not speak at all about the relationship of sponges and volvoxes. Apparently, the sponges occurred from the colonies of primitive collar flames, similar to Volvox.

Sponges are not fundamentally different from the other multicellular animals. Their homoanocites, or digestive cells, are located in one layer, as with the rest of Metazoa. The collar cells are also available in other multicellular: some iglinodoki ( sea hedgehog, dowry) and intestines. The formation of genital cells (spermatogenesis and oogenesis) and the structure of spermatozoa do not differ from those even highly organized multicellular. In some ordinary sponges (Demospongia) ^ at all occurs in the instrument of primary (germ) layers during the development of limestone sponges, four-beam symmetry is manifested (four large cells form a cross), highly characteristic of intestinal, larvae polycete, ga-truck and cipunculide. About the relationship of sponges with the rest of the multicellularity is also indicated by the similarity of the larvae of sponges with larvae of intestinal and iglozzy.

All information provided confirms the theory of the general origin of sponges and other multicellular.

The absence of nervous and muscular systems in sponges speaks of their primitiveness. Sponges can be put at the very beginning of the general barrel of Metazoa.