Although lampreys have some resemblance to the fish, these animals are not fish, and representatives of more primitive vertebrate class Cyclostomata). In this family, except lampreys are hagfish. Evolutionary cyclostomes are precursors of fish.
The similarity with the fish lamprey attach habitat (both aquatic animals), body shape (lampreys similar to acne) and fins (however, lampreys they unpaired).
However, in common with fish in lampreys end. Differences are much more:
- The lamprey has no spine and bony skeleton. Instead of a backbone at them along the back passes chord (spinal chord), consisting of cartilage.
- The lamprey has no scales. Leather lampreys smooth, and its numerous glands secrete a large amount of mucus.
- The lamprey no paired appendages.
- Respiratory system lampreys and fishes is also different. The lamprey respiratory system presents the internal gills. They look like spherical bags, which are connected by holes on one side with the throat, and on the other with the external environment. On the sides of the body lampreys you can see the holes are the outputs of the Gill bags. Water is pushed out through the exterior openings of bags with the help of muscles and through them can be absorbed. Therefore, if the fish water is supplied to the gills with the ingestion of water by mouth, lamprey can breathe and when your mouth busy food - and this is very important in their diet (see below).
- The lamprey has no jaws.
The mouth of the lamprey round, surrounded by a suction Cup. Inside - in pregroove funnel are Horny teeth.
The mouth of the lamprey
What and how they eat creatures with such original mouth? With suction cups lamprey clings to his food and grinds her teeth. Most lampreys are parasites of fish. Lamprey clings to the body of the fish, prosurvival her skin and starts to inject into the body of his victim substances that prevent clotting of the blood, anticoagulants, as well as digestive enzymes. Thus, food lampreys begins to be digested before they absorb it, and they suck already partially digested food. This type of food is called extraintestinal or vnepolozhnym, digestion.
Fish-the victim is a parasite until you die from exhaustion.
Lampreys are parasites
And lamprey on such a diet may reach a length of 120 cm and a weight of 3 kg! Live lampreys 5-7 years.
Among lampreys are marine, freshwater and anadromous species. But all eels breed only in fresh water. Larvae of lampreys similar to yellowish worms. They like to rest, buried in sand or mud. For this they called pastoralcare.
Lampreys are the objects of trade. Meat lampreys are considered a delicacy.
In the last decades of the lamprey was on the verge of extinction because of engineering and severe pollution of spawning rivers, and also because of the sharp decline in the number of fish hosts.