The underwater world is so diverse and unique that sometimes it is even difficult to distinguish plants from animals. Such bizarre forms are the creatures living there. Large sea giants and very microscopic planktonic crustaceans, colorful and bright, predators and herbivores - an insane variety of species of living organisms. One of these amazing creatures are sponges, which will be discussed later.
General information
You can characterize the position of these animals in the system of the organic world as follows:
- empire - Cellular;
- kingdom - Animals;
- subkingdom - 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.
- Calcarea, or Calcareous. They form the external skeleton in the form of deposited calcium s alts.
- Ordinary, or Kremnerogovye. The main representative is a badyaga.
- Glass (Six-beam). The class size is small.
- Corals are a species-poor class.
All listed sponges haveits features not only external, but also internal structure, lifestyle and economic significance in human life.
Exterior structure
Perhaps, the most unusual in the whole characterization of the animals in question will be exactly the external appearance. The 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:
- glasses;
- bowls;
- tree structure.
The symmetry of the body in single forms is bipolar axial, in colonial forms it is mixed. Each individual has a special flat sole, with which it is attached to the bottom or other substrate. Sponges are most often immobile.
On the upper side of the body there is a special hole, which is called the "osculum". It serves to remove excess water from the internal cavity. Outside, the body is covered with a layer of cells - pinacoderm. 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 provides for the absorption of food particles not through the upper hole, but through numerous perforations penetrating the entire body, capable of contracting and expanding.
There are two more under the outer layer, which we will consider in more detail later. The color scheme of both single and colonial forms is quite diverse. The following types of coloring are found:
- grey;
- green;
- purple;
- yellow;
- white;
- red;
- brown;
- mixed.
The Sponge Type brings the underwater world to life, making it even more vivid, colorful and attractive. Moreover, if we consider a single individual on the land surface, then it will have a very unattractive appearance: a brownish slippery lump resembling a raw liver, emitting a not very pleasant aroma.
Internal structure of representatives
The body types of sponges are similar, whether solitary or attached to a colony. Immediately under the dermal outer layer of porous cells is a special intercellular substance that forms a fairly voluminous membrane. In it, the cells are located loosely, and their shape is different. The tissue is somewhat reminiscent of fatty tissue in higher terrestrial representatives. This structure is called "mesochil".
Under this layer is an internal cavity lined with a special row of cells. This is the gastric layer. All food goes here, and digestion takes place here. All waste products, along with excess water, are directed to the upper body opening and are discharged through it to the outside.
Also, the structure of the sponge necessarily includes a kind of skeleton. It is formed from lime, phosphorus, organic s alts, which are produced in special mesochil cells. It not only gives the sponges a certain shape of the body, but is also important for the preservation of the internal cavity from mechanical damage.
Characteristic Sponge typewill be incomplete if you do not identify the main feature of these animals - their body does not have tissues, but only includes cells of various shapes and structures that form layers. This is the main difference between the animals in question and all others.
The aquifer system of individuals is also interesting. It may be different for different classes. In total, there are three main types of it:
- Ascon - all communication with the external environment is carried out through a system of tubes through which water moves into special cell-chambers. The most simplified aquifer system found in a few representatives.
- Secon. A more advanced system, which includes a network of branched tubules and tubules that flow into special cell-cameras with flagella.
- Lacon - a whole network of osculums, this type of aquifer system is typical only for colonial forms. The most complicated option compared to all the previous ones.
Sponges reproduce both sexually and asexually. Sex cells are formed in the mesohyl layer. Then the products go out through the pores of the body and with the flow of water enter the bodies of other sponges, where fertilization occurs. As a result, a zygote is formed, giving rise to a larva. The fry can be called differently: amphiblastula, parenchymula, celloblastula.
If we talk about asexual reproduction, then it is based on the process of budding, that is, detachment of a body part with subsequent regeneration of the missing structures. Most of the Sponge type includes hermaphroditicanimals.
Lifestyle features
If we consider all the diversity of multicellular animals of the world, then sponges should be attributed to the most primitive stage in terms of organization. However, these are 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. Representative life form has two manifestations:
- single;
- colonial.
Most often found massive accumulations of sponges among coral reefs. There are both freshwater species (their minority) and inhabitants of the seas and oceans (the overwhelming majority of species).
Sponge type 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 capture the floating particles of food, directing them into the internal paragastric cavity of the body. Digestion takes place inside the cells.
By the way they get food, sponges can be called passive hunters. They sit lazily in an attached place, waiting for passing nutrient particles. And only when they are already very close, they capture them through the pores and direct them, together with the current of water, into the body.
Some species are able to move, despite the fact that they still have soles for attaching to the substrate. However, their speed is so low that for the whole day the individual is unlikely to move further than a meter.
Variety of sponges
For suchprimitive animals, the diversity of representatives is quite impressive - after all, there are about 8 thousand species of them! And according to some modern data, this figure is already approaching 9 thousand. External diversity is explained by the difference in body shape, skeleton types and body color of individuals (or colonies).
Class Glass Sponges
Glass sponges are very interesting in their external variety. They are not as numerous as others, but have an unusual skeleton. These are one of the largest individuals that the Sponge type includes. The general characteristics of the representatives of this class can be expressed in several points.
- Latin class name - Hexactinellida.
- The skeleton is formed from silicon compounds, so it is very strong.
- Needle type body support, dominated by six-pointed structures.
- Larvae of parenchymula or coeloblastula species.
- Leukon-type aquifer system.
- More often colonial than solitary forms.
- Sometimes up to 50 cm in height.
The most common representatives are:
- hyalonema siboldi;
- euplectella.
Class Ordinary, or Silicon Horn sponges
The type of Sponge, the photo of the representatives of which can be seen in this article, also includes the most numerous class in terms of the number of individuals - Kremnerogye, or Ordinary. They got their name for the features in the structure of the skeleton - it consists of silica and spongin. Byhardness is quite delicate and easily broken. The shape of the spines of the skeleton is very diverse:
- asterisks;
- anchors;
- clubs;
- sharp needles and so on.
The most common freshwater representative is badyaga - a sponge used as an indicator of the purity of the reservoir. Outwardly unattractive, the color is brown-brown, sometimes dirty yellow. Used by man for various needs.
What other representatives are found among ordinary sponges?
- Mixils.
- Sea loaf.
- Baikal sponge.
- Sea brushes.
- Giant chondrocladia and others.
Class Lime Sponges
It includes representatives with a strong and beautiful calcareous skeleton. They live only in the seas and oceans. The coloration is pale or completely absent. The spines of the skeleton may have about three rays. Main representatives: ascons, sicons, leucandras.
Class Coral sponges
The fewest representatives that outwardly resemble coral branches. This happens due to the formation of a powerful calcareous skeleton of different colors and patterned structure.
Representatives: Nicholson's geratoporella, merlia. In total, only six species of such animals have been described. For a long time they were not distinguished from the coral reef system, so they were discovered relatively recently.
Human use of sponges
The economic importance of individuals belonging to the Sponge type is also important. Representatives are used in the followingneeds:
- They are participants in the food chain, as they themselves serve as food for many animals.
- Used by people to make beautiful body and home decorations.
- Contain substances that allow them to be used for medical purposes (the bodyaga sponge has an absorbable bruise and wound healing effect).
- Used to create hygienic sponges - natural natural products for the cosmetics industry.
- Used for technical and other purposes.
