Type of Sponge. Features of the structure and classes of sponges

The underwater world is so diverse and unique that sometimes it is even difficult to distinguish plants from animals. So bizarre forms are living creatures. Large sea giants and very microscopic planktonic crustaceans, colorful and bright, predators and herbivores - insane variety of species of living organisms. Some of these amazing creatures are sponges, which will be discussed later.

general information

The position of these animals in the system of the organic world can be characterized as follows:

• Empire - Cellular;
• Kingdom - Animals;
• Sub-kingdom - Multicellular;
• Type - Sponges.

To date, it is known that there are about 8 thousand species. 300 of them inhabit the expanses of the seas of our country.

Classification

The Sponge type combines all known representatives into four large classes.

1. Calcarea, or Calcareous. Form the outer skeleton in the form of deferred calcium salts.
2. Ordinary, or Silicon. The main representative is a badyaga.
3. Glass (Six-beam). The class size is small.
4. Coral is a very poor class.

All these sponges have their own peculiarities not only external but also internal structure, lifestyle and economic significance in human life.

External structure

Perhaps the most unusual in the entire character of the animals in question will be the external appearance. Features of the external structure of the sponge are determined by the variety of body shapes that are characteristic of them. So, representatives of different classes can be in the form:

• A glass;
• Bowls;
• Tree structure.

Symmetry of the body in single forms is multipolar axial, in colonial - mixed. Each individual has a special flat sole, with which it is attached to the bottom or other substrate. Sponges often lead to a fixed lifestyle.

On the upper side of the body is a special hole, which is called "oskulum." It serves to remove excess water from the internal cavity. Outside, the body is covered with a layer of cells - pinakaderma. They resemble in their structure the epithelial tissue of higher animals.

However, they also have distinctive features - the presence of wide pores. The structure of the sponge involves the absorption of food particles not through the upper opening, namely through numerous perforations penetrating the entire body, capable of contracting and expanding.

Under the outer layer there are two more, which will be discussed in more detail later. The color scheme of both single and colonial forms is quite diverse. There are the following types of color:

• Gray;
• Green;
• Purple;
• Yellow;
• White;
• Red;
• Brown;
• Mixed.

Sponge type very animates the underwater world, making it even more vivid, colorful and attractive. In this case, if we consider a single individual on the surface of the land, it will have a very unattractive appearance: a brownish slippery lump resembling a moist liver, which produces an unpleasant aroma.

Internal structure of representatives

The types of the structure of the sponges are similar, whether it is a single individual or attached to a colony. Immediately under the dermal outer layer of porous cells is a special intercellular substance, which forms a sufficiently volumetric shell. In it, the cells are loose, and their shape is different. The fabric is somewhat reminiscent of fatty in higher land representatives. This structure is called "mesohil."

Under this layer there is an internal cavity lined with a special row of cells. This is the gastral layer. All food gets here, and there is digestion. All wastes of vital activity, along with surpluses of water, are directed to the upper opening of the body and are led out through it.

Also, the structure of the sponge necessarily includes a peculiar skeleton. It is formed from calcareous, phosphoric, organic salts, which are produced in special mesohila cells. It not only gives the sponges a certain shape of the body, but it also has value for safety against mechanical damage to the internal cavity.

Characteristics of the type of the sponge will be incomplete, if not to designate the main feature of these animals - their body does not have tissues, but only includes various cells in the form and structure that form the layers. This is the main difference between the animals in question and all others.

The aquifer system of individuals is also interesting. It may not be the same for different classes. There are three main types of it:

1. Ascon - all communication with the external environment is carried out through a system of tubes, through which water moves into special cells-chambers. The simplest aquifer system, found in a few representatives.
2. Sikon. A more advanced system, including a network of branched tubules and tubules, flowing into special cells-chambers with flagella.
3. Leukon is a whole network of osculums, this kind of aquifer system is characteristic only of colonial forms. The most complicated version on the background of all the previous ones.

Reproduction in sponges occurs both sexually and asexually. Genital cells form in the mesohil layer. Then the products go out through the pores of the body to the outside and flow into the bodies of other sponges with the current of water, where fertilization takes place. As a result, a zygote is formed, giving rise to the larva. Fry can be called in different ways: amphiblastules, parenchymules, celloblastules.

If we talk about asexual reproduction, then it is based on the process of budding, that is, detaching a part of the body with the subsequent regeneration of the missing structures. Most of the type of the sponge includes hermaphroditic animals.

Lifestyle Features

If we consider all the diversity of multicellular animals in the world, then we should include the sponge to the most primitive in organization steps. However, it is also the most ancient animals that appeared many thousands of years ago. During the evolution of their organization, little has changed, they retain their characteristics over time. The life form of representatives has two manifestations:

• Single;
• Colonial.

The most common are found mass accumulations of sponges among coral reefs. There are both freshwater species (their minority), and inhabitants of the seas and oceans (overwhelming in the number of species group).

The type of sponge includes animals that feed on small organisms or their remains. In the structure of their body there are special collar cells with flagella. They just grab the floating particles of food, directing them into the internal paragastric cavity of the body. Digestion is carried out inside cells.

By the way food is extracted sponges can be called passive hunters. They lazily sit on the fixed place in anticipation of floating nutrient particles. And only when they are already very close, grab them through the pores and send along with the current of water inside the body.

Some species are able to move, despite the fact that they still have a sole for attachment to the substrate. However, their speed is so low that for the whole day the individual is unlikely to move further than a meter.

A variety of sponges

For such primitive animals, the variety of representatives is quite impressive - there are about 8 thousand species! And according to some modern data, this figure is already approaching 9 thousand. External diversity is explained by the difference in the shape of the body, the types of the skeleton and the coloration of the body of individuals (or colonies).

Class Glass jaws

Very interesting in its external variety of glass sponges. They are not as numerous as others, but they have an unusual skeleton. This is one of the largest individuals, which includes the type of sponge. General characteristics of representatives of this class can be expressed in several paragraphs.

1. The Latin name of the class is Hexactinellida.
2. The skeleton is formed of silicon compounds, so it is very durable.
3. Needle type of body support, in which six-pointed structures predominate.
4. Larvae of the parenchymula or of the whole cellulostula.
5. Aquifer system of leucon type.
6. More often colonial than single forms.
7. Sometimes up to 50 cm in height.

The most common representatives are as follows:

• Hialonema siboldi;
• Euplectella.

Class Ordinary, or Silicon, sponges

The type of sponge, the photo of whose representatives can be seen in this article, also includes the most numerous in the number of individuals - Silicon, or Ordinary. Its name was given for features in the structure of the skeleton - it consists of their silica and spongin. The hardness is gentle enough and it easily collapses. The shape of the skeleton needles is very diverse:

• Asterisks;
• Anchor;
• Maces;
• Sharp needles and so on.

The most common freshwater representative is the sponge-sponge, used as an indicator of the purity of the reservoir. Outwardly unattractive, the color is brownish-brown, sometimes dirty-yellow. Used by man for different needs.

What other representatives are found among ordinary sponges?

1. Mixils.
2. The sea loaf.
3. The Baikal sponge.
4. Marine brushes.
5. Giant chondrocladia and others.

Class Lime Sponges

It includes representatives who have a strong and beautiful calcareous skeleton. They live only in the seas and oceans. The color is pale or completely absent. Needles of the skeleton can have about three rays. The main representatives: ascona, sikony, leukandra.

Class Coral sponges

The fewest representatives that outwardly resemble coral twigs. This is due to the formation of a powerful limestone skeleton of a different color and patterned structure.

Representatives: geratoporella Nicholson, merlia. Only six species of such animals are described. For a long time they were not distinguished from the system of coral reefs, so they were discovered relatively recently.

Using sponges by a person

Important and economic importance of individuals belonging to the type of sponges. Representatives are used in the following needs:

1. They are participants in the food chain, since they themselves serve as food for many animals.
2. Used by people to make beautiful body jewelry and home interior.
3. They contain substances that allow them to be used for medical purposes (the sponge has a resorptive bruising and wound healing effect).
4. They are used to create hygienic sponges - natural natural products for the cosmetic industry.
5. Used for technical and other purposes.