The most important function is assigned to fish fins: it is they that help the fish move in the water and change their trajectory, sometimes surprisingly quickly. But the number of fins is not the same for all aquatic inhabitants, there are fish with 4 pairs, and there are those with as many as 8 pairs of fins.
Fin types
The number of fins depends a lot on the type of fish. Traditionally, fins are divided into two main groups: paired and unpaired. Paired are abdominal and thoracic. The caudal, dorsal and anal are considered unpaired. With the help of the tail, the fish begins to move, it is this fin that pushes it forward with a strong movement. The dorsal and anal are designed primarily to keep the fish body in the water.
Few fish species also have an adipose fin located between the dorsal and caudal fins.
Different fish species have different numbers of dorsal fins. For example, carps and herring are endowed with one dorsal fin, and perch-like have two fins, but cod-like ones have three dorsal fins.
Fin functions
The location of the fins can also be different, for example, in a pike the fin is displaced to the end of the body, in carps and herring fish it is located in the middle, in cod - near the head. And tuna and mackerel even have extra small fins behind the dorsal and anal fins. There is a type of fish (scorpion fish), which have poisonous glands in the dorsal fin. There are also simply organized fish in which fins are completely absent (cyclostomes). The more fins a fish has, the better it is oriented in the water space, and the easier it is for it to move through the water column.
The pectoral fins are used by fish for slow swimming. In addition, the pectoral fins, along with the caudal and pelvic fins, help keep the fish balanced in the body. Most fish that swim on the bottom move along the sea land thanks to their pectoral fins.
A small group of inhabitants of the aquatic environment (for example, moray eels) have no pelvic and pectoral fins at all. Some species may even lack a tail (for example, seahorses, moonfish, stingrays, etc.)
The fin is a vital part of the fish body. In addition to moving in water, on land, as well as performing various jumps and leaps, fins help fish to attach to something, get food and even endow them with some specific protective properties. For example, gobies have special fins-suckers, trigly, thanks to the fins, easily get their food, and the fins of sticklebacks are endowed with protective functions.
