All the variety of fish on the planet can be divided into two classes, which, first of all, include cartilaginous fish, which include 730 species (sharks, slopes and others), whose body does not ossify, because it includes cartilage, as well as bone , numbering 250 thousand species (from sturgeons to crucian carp), which have a full skeleton formed.
General characteristics of fish species
The main and main criterion for the division of fish into species, as you can understand from the name of the classes, is the internal skeleton of the animal.
The skeleton of fish of the bone group consists of bone formations, and cartilaginous fish have a skeleton, which includes cartilage.
Another feature of many types of cartilaginous fish is the way of internal fertilization, t.e. the possibility of livestock: as in mammals, their kids ripen inside the mother’s body, and is born adapted to independent existence and nutrition.
But the bone group is characterized by the external method of reproduction, and adapted to multiply thanks to the spangling; Their offspring is hatched from eggs, postponed by parents in hidden places.
Carty fish do not have a floating bubble, and their scales are not capable of restoration, while bone fish have this advantage.
General features and differences in fish species
If we talk about general terms, then cartilaginous fish and fish of the bone group belong to the chordovs, have approximately the same body structure (elongated and streamlined), the presence of fins and gills. Both of these species are characterized by one circle of blood circulation and twochamber hearts, and in general similar blood systems, the differences of which are only in minor details.
In bone fish, as in the fish fish fish, the skin consists of an epithelium (and multilayer), as well as a connective tissue browntype brown. And the numerous glands of the skin of a unicellular format in these fish provide secretions of mucous secretion, which is a small layer common throughout the body of fish.
The transversely broken muscle of somatic type in bone fish, as well as in fish groups, is distinguished by a distinct segmental of muscle segments with a complex form.
If we talk about the differences in these species, then the skeleton of cartilaginous fish is formed from cartilaginous fabric, and it remains unchanged all life, and these fish do not have gill covers that are replaced by gill slits, and the tail fin is unequilled. Whereas bone fish is the opposite.
Differences and similarities of cartilage and bone fish table
| 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 |
| eight | Spray | There is | 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 |
| 12 | Skeleton | Cartilaginous | Bone |
| 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 |
| Cloaca | There is | Missing | |
| 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 |
