Today we will talk about cartilaginous fish. The class is one of two large groups of living fish, the second of which is ostehytians, better known as bone fish.
- The structure of cartilage fish
- Systems of cartilage fish
- Representatives of cartilage fish
- Golocephals (chimeras)
- The origin of the cartilaginous fish
- Signs of cartilaginous fish
- Features and characteristics of cartilaginous fish
- Propagation of cartilage fish
- Where live?
- What they eat?
- The value of cartilaginous fish
- Comparative table of cartilage and bone fish
The structure of cartilage fish
The skeleton of cartilaginous fish consists of cartilage, not bones, like the rest of the fish. Chord, which is present in young animals, is later replaced by cartilage.
At the end of the body there is a heterotrocal tail, that is, it has two shares of different shapes and structures, in one of them there is the end of the spinal column, and a pair of thoracic fins, a pair of abdominal fins, two unpaired spinal fins are placed in front of them. In males, abdominal fins are modified, the function of the penis is performed.
The teeth are not fraught with the jaw and have two rows, the rear replaces lost teeth from the front, and thus new teeth always appear in cartilaginous fish. They, depending on the species, can have a jagged shape to cut food, are sharp, with a grasping function, and in slopes flat teeth that allow them to scratch the surface.
They have paired nostrils located in front of the mouth. There is no century before our eyes, although some species have a flashing membrane and a spard of each.
The eye is the most complex organ of the head and is the lateral separation of the front end of the brain tube. Then he acquires a lens of epidermal origin. There is a line of channels filled with fluid, which walk on the sides of the fish, which allow it to detect movement and vibration in water. Olfactory pits blind bags that open into the external environment containing olfactory receptors. Size depends on the fish.
Neromassts, receptor organs that are extremely sensitive to vibrations and water currents are located along their body and head. Carty fish also have special receptors that allow them to detect their prey according to the emitted electric field “Lorencini ampoules” that are located on the head.
Systems of cartilage fish
The digestive system consists of a mouth, a long throat, an esophagus leading to the stomach, a short rectum in which digestive juices secreted by the liver and pancreas fall, cloak. Unbertable food residues and metabolic products from the excretory system fall into the cloaca. In females, the cloac is also the final part of the reproductive system.
The blood system is closed, with one contour and a twochamber heart. In the heart there are membranous valves that prevent the reverse flow of blood. Thanks to the rhythmic contractions of the heart, deoxigenized blood is pumped from the heart chamber to the gills, from which it takes oxygen and releases carbon dioxide. Then, in arterial vessels, oxygen is distributed throughout the body, and at the same time carbon dioxide is collected. Deoxigenized blood returns through the veins to the venous sinus of the heart, from where it flows into the atrium. The circulatory system of fish (especially fastfloating species) is very operational and effective.
Carty fish breathe gills located on gill partitions. The continuous movement of water flowing through a mouth washing gills and flowing through 5-7 pairs of gill cracks, supplies fish dissolved in water with oxygen. Akulas actively floating in the water column forces the water to flow through the gills, in turn, the bottom sharks, mainly use the muscles of the throat for this purpose; Skas suck water through the rinseum a hole located on the back of the head, which is a transformed gill gap, which is originally between the mandibular and sublanguage arcs.
All cartilaginous fish does not have a floating bubble, the gas content of which balances the body weight in water and does not allow you to drown. For the most part, sharks compensate for this drawback with a huge, very fat liver, which can be up to a quarter of mass and occupy 90% of the body cavity, is not surrounded by a protective chest.
Advantage: sharks can freely and quickly move between a variety of water depths without the need to adjust the content of gas in the swimming blade. Disadvantage: they either have to actively swim so as not to sink, or to go to the bottom.
Sharks and other cartilaginous fish do not have scales as a protective coating of the body, but have a dense, very durable layer of tiny skin cloves. As a result, the skin of most sharks is rude, like sandpaper.
Skin teeth are formed in the upper layer of the skin, epidermis, and firmly fixed in it with starry roots equipped with nerves and blood vessels, as well as jaw teeth. Unlike bony, in cartilaginous fish, scales do not grow along with the animal, but falls and replaces larger scales.
They perform a double function: on the one hand, they are used to protect the animal, and on the other, to provide more hydrodynamics. To reduce turbulence, they are turned back. This surface turned out to be so hydrodynamically ideal that this structure is used for modern aircraft industry.
All dermal teeth are oriented in one direction, therefore, if you stroke the body of cartilage in one direction, it will seem completely smooth, and if in the other, it will be rough to the touch. In addition, some cartilaginous fish may have mucous glands that release a substance on the body that increases their ability to efficiently swim.
Representatives of cartilage fish
These are predators who find their prey with the help of smell organs, since their eyesight are poorly developed. There are currently 8 sharks detachments consisting of more than 400 types.
They are characterized by a heterotrocal tail (the upper half is longer than the lower), five to seven gill slots for breathing and a rounded body, tapering to both ends.
Damobile sharks this includes horned sharks, such as Heterodontus francisci. They are small and live in the warm and moderate waters of the Indian Ocean, the western part of the Pacific Ocean. There are no in the Atlantic.
Catranshaped. The species that make up this group are deprived of a migratory membrane and anal fins. Inhabit the deep waters of the Atlantic Ocean. They are mediumsized, and some of their species have toxic spikes on the dorsal fins.
Piloned sharks: This group includes the so-called shark-saws. They have an elongated and jagged face in the shape of a saw, which serves to move in silt and look for food, the basis of which is squirrels, shrimp and small fish.
Flat sharks: includes sharks-angels. They have a flattened shape and wide chest fins, resemble slopes. They are quite widespread, as they are found in the Atlantic Ocean, Mediterranean, Dead and the North Seas. Some species may make migrations.
Multisequentialshaped these include the most primitive sharks that exist today. One example is Hexanchus nakamurai, a largeeyed cow of a shark that lives in the Atlantic and Indian oceans. Although it looks dangerous, eats invertebrates and is harmless to a person.
Vobbegogongshaped: these are heatwater shortmoraine sharks with a small mouth. They inhabit seas and oceans around the world. Includes the largest of the existing sharks, a whale shark Rhincodon Typus. It lives in warm tropical and subtropical waters, has a filter power system, which, in addition to the appearance, makes it similar to whales.
Carharinlike this detachment is the most diverse, found in tropical, moderate and deep waters around the world. They have an elongated snout and a large mouth, there is a migating membrane that protects their eyes. This includes one of the most famous sharks: the Tiger Shark Galeocerdo Cuvie, which received this name because of the stripes on the sides and back.
Lamplike: these are the most famous sharks, for example, a white shark, known as a species that often attacks people. Lives in warm and moderate waters of almost all oceans.
By the way, about attacks. Sharks are one of the most incomprehensible creatures. But pop culture is excessively exaggerated by the danger that they represent for a person. There is little evidence that sharks hunt people for food.
A disproportionately large number of attacks occurs near the habitats of seals and sea lions. Slubs whose rowing resembles the behavior of a seal on the surface, are attacked with a greater probability than scuba divers. These factors indicate that sharks can mistakely take people for seals, or other large sea booty. Submarine hunters transporting wounded fish are also at a greater risk of shark attacks: the vibrations of fighting fish can attract a predator, so the catch should always be immobilized.
Most sharks attacking people are Macelli sharks, including large white sharks and obstetric sharks; predators of these families feed on large fish or marine mammals. The Aculames-River include a tiger shark and bull shark, which feed mainly by other sharks. Akules-young people specialize in the attack on stingrays.
The whale sharks feeding on plankton are the largest fish in the world, their length reaches 18 meters (60 feet). Other large power plankton includes accurately these trigtes and giant sharks. They swim with an open mouth, filtering plankton through modified structures associated with gills.
While larger sharks are much more known to the general public, small species are much more diverse and numerous.
Common for 470 species of this diverse group of fish is a flattened body with advanced breast fins, fused with the head. Batoids are common throughout the world ocean and in some tropical freshwater media.
They are divided into 4 detachments:
Scatoal: these are the socalled real slopes. Types can be found in all oceans: from Arctic to Antarctic. For example, Potamotrygon Motoro freshwater slopes, inhabitants of the tropical waters of South America. You need to be afraid of the sting at the end of their tail fin, as the attacks of this species on people were registered.
Pilory slopes: they are called pilaf fish, because they have a long toothy face, for example, in prestis pectinata, which also has a flattened body and winged chest fins. They live in tropical and subtropical waters around Africa, Australia and the Caribbean, hunt at night.
Electric slopes-they are usually called a-grape or electric scan, since they can issue an electric discharge to stun their prey and predators, using electrical organs located at the base of the chest fins. These are the inhabitants of all moderate and tropical seas of the world, for example.
Carefoot: this is a group, closely related to the scatoral, since they are very similar to each other. These are the biggest slopes in the world, and this includes Manta Mobile Birostris. The difference from the first detachment they have no sting in the tail fin. Live in the warm seas around the world.
MyliobatidiFormes detachment includes several types of slopes. Large roller slopes (Myliobatidae) have strong muscular breast fins for fast swimming. Skas Manta (mobulida) the largest slopes reaching width of about 7 meters; Like the largest sharks, they have a special mouth for feeding plankton. Skas (dasyatididae) have a tail ending with a flexible whiplike area equipped with one or more poisonous spikes.
People walking on the sandy bottom, especially in calm water, often risk stepping on the slope and be stung, so when walking along the sandy substrate, you should always shuffle their feet. These animals almost never sting if they are not provoked; The attack is often preceded by a warning stand when the tail is pulled forward above the body.
Today this small group has approximately 47 types. Anatomically, it combines the features of plastic and bone fish:
They feed mainly with mollusks and other invertebrates in a mule, crushing hard shells with their flat teeth. Characterized by large heads and eyes, as well as a long thin tail. They have a gill cover, a solid bone layer of fabric covering the gills, which is found in many bony fish, but is absent in all cartilage.
Golocephals are classified only in one detachment of chemer-shaped, a group, which includes chimeras or ghosts. There are only three families here:
There are few differences between them, some species have a very long snout with nerve endings that allow them to detect small prey. An example is the ordinary chimera Chimaeera Monstrosa, which lives in the Atlantic Ocean and the Mediterranean Sea.
The origin of the cartilaginous fish
According to fossils (mainly on the basis of shark teeth, which persist much longer than any other part of the shark), the earliest sharks appeared about 400 million years ago. “Modern” sharks appeared about 35 million years ago, and megalodons, white sharks and sharks-young people-about 23 million years ago.
Skates and chimeras exist longer than we, but the annals of their fossils are dated about 150 million years ago, so they appeared much later than the first sharks.
Signs of cartilaginous fish
In cartilaginous fish, the absence of a swimming bladder is one of their signs. Therefore, these fish, when they do not swim, fall to the bottom. Some species swallow air to reduce the specific gravity, others accumulate a large amount of fat in the liver. They can thus balance their specific gravity with a specific gravity of water.
The remaining species use the movement to retain in the water column, their paired fins are motionless. The role of the lift was taken by the tail fin. Another feature of these fish is the presence of mobile and motionless eyelids, which probably serve as mechanical protection for the eyes. Gills are not covered with a lid.
Features and characteristics of cartilaginous fish
They are distinguished by the following characteristics:
Propagation of cartilage fish
Another important feature of cartilaginous fish is internal fertilization. The reproductive system is equipped. Males have a copulative organ formed from the abdominal fin.
Mating of cartilaginous fish occurs thanks to the “fasteners” of males, also known as mixersopteria, which are inserted into the cloaca of females. Only one of the two clammers is used simultaneously and is pushed at an angle of about 90 ° to copulate.
To fix fasteners in the cloak, they have cartilage spikes. These predators contain a dorsal groove through which packages with sperm fall into the genitals of the female. The mucus necessary for this is formed in the sharks in a special siphonal bag lying between the skin of the abdomen and muscles, and in slopes in the buckle glare; Immediately before mating, this bag is filled with water, and the mucus contained in it is diluted accordingly, before it merges through the hole at the base of the fasteners, along with sperm into the gutter.
This allows many species to be lively, and in other types, the formation of eggs is surrounded by a cornea, which makes it difficult to destroy them. The eggshell is often equipped with appendages that allow them to attach to the bottom or water vegetation. Thanks to this, the newborn young animals are quite large and can immediately move on to a predatory lifestyle. For example, in a sandy tiger (Odontaspis Taurus), predation begins during the period of embryonic development. The first and most powerful embryos hatching in the phallopium pipes of the female are devouring younger brothers and sisters. Therefore, it can grow no more than two newborn, each in one of the fallopian tubes.
More detailed about each method of reproduction:
Ovilinstrumental: lay eggs with yolk immediately after fertilization. Many sharks and slopes lay eggs in a horn capsule, which forms at the ends of the antennae, which help them stick to the first solid object, to which they touch, and the embryo can be inside 6 months to 2 years. As a rule, this modality is found in small and bottom species, and they can put off up to 100 eggs.
Vigators: they develop a real placenta from which the embryo eats. This reproductive method contributed to the evolutionary success of this group. It occurs in almost 60% of fish fish.
Egggrownups: retain the embryo in the oviduct while it develops. In turn, there are different types of nutrition of the embryo in the egg, such as:
Carty fish live around the world, in all types of water: from slopes living in shallow water with a sandy bottom, to sharks living in a deep open ocean.
What they eat?
The diet of cartilaginous fish depends on the type. Sharks are the highest predators and can eat fish and marine mammals, such as seals and whales. Skas, who mainly live at the bottom of the ocean, eat other inhabitants of the bottom, including marine invertebrates, such as crabs, mollusks, oysters and shrimp. Some huge cartilaginous fish, such as whale sharks, giant sharks and manti, feed on tiny plankton.
The value of cartilaginous fish
Shark meat is eaten in all naval countries. It can be prepared in various ways: fresh, salty, smoked or pickled sold in such forms as steaks, fillets or flakes.
Since ancient times, the Chinese have used the fins of some sharks and stingrays as the basis of Epicurean soup. To satisfy the demand for this product, they imported fins from distant countries. The fins are prepared for sale, removing the skin and meat, leaving only the gelative rays rich in gelatin, which are dried before sending.
Fat from the liver of sharks is used in various regions for:
The liver of a giant shark (Cetorhinus maximus) contains from 300 to 2300 liters of oil, which was used in lamps until the oil products were replaced by animal fat for lighting.
Solid scales provide the abrasive surface of the skin of sharks and some slopes, giving it special value, since such skin is used to polish solid wood. When heated and polished, shagren is used for decoration, and in Japan to cover the handles of swords. It is much more durable than cowls, used for shoes, belts, wallets and other accessories.
About 114,000,000 kg of slopes are sold in food in various countries of the world, mainly in Europe and Asia. Side products that are in demand among local residents are skinshaped skin skin for drum plates; scaly species are used for shag. The liver goes to oil, fins for gelatin.
Residents of many tropical regions Polynesia, Oceania, Malaysia, Central America and Africa used straps for the manufacture of items such as needles and awl, copies and daggers, as well as for the manufacture contained in them. The entire tail of slopes with spikes was used as a whip in various tropical areas.
The ancient Greeks and the Romans used the electric shock to relieve spleen diseases, chronic headaches and gout. Today, these fish are concerned with swimwear who step on them, and in fishermen who can be affected by current when wet nets are pulled out.
Comparative table of cartilage and bone fish
|No||Features||Class Carty Pisces (Chonodrichthyes)||Bone fish class (Osteichthyes)|
|one||Number of species||About 730||More than 20,000|
|2||The environment of life||Mostly marine species||Many freshwater species|
|3||Dimensions||From 15 cm (dwarf shark) up to 20 m and mass 15,000 kg (whale shark)||From 7 mm (pandaca) to 5-7 m and mass 500-1 500 kg (beluga)|
|four||Body||Naked or covered with placine scales||Coated with bone scales|
|5||Pair fins||Located horizontally||Located vertically|
|6||Tail fin||HeterotroChurch||Mostly hom church|
|7||Rostrum||There is||Mostly absent|
|9||Gill slits||5-7 pairs||1 pair|
|ten||Gill covers||Absent||There is|
|eleven||Gills||They have the form of plates that have grown to interjacket partitions||Have the form of freely hanging petals|
|13||Swimming bubble||Missing||There is|
|fourteen||Arterial cone in the heart||There is||Missing|
|fifteen||Intestinal surface area||Increases due to the spiral valve||Increases due to loops and pyloric processes|
|17||Caviar||Lay eggs surrounded by a solid shell||Throw a lot of fine caviar without hard shells|
|eighteen||Fertilization||Almost everyone has internal||Mostly external|