fin (zoology)

The fins . They are the external organs that many aquatic animals use for locomotion and balance.

Summary

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• 1 Types of fins
  • 1Pares
    • 1.1Pectorales
    • 1.2 Pelvic or ventral
  • 2Impares
    • 2.1 Dorsals
    • 2.2 Whales, dolphins, and porpoises
    • 2.3 Caudal
    • 2.4Anal
    • 2.5 Aleta adipose
  • 2 Sources

fin types

Pares

They are the ones that are even as most fish have them.

pecs

They are located behind the openings of the gills.

Pelvic or ventral

Immediately in front of the back.

Those fins have an evolutionary relationship with the limbs of terrestrial vertebrates . Its function is mainly stabilizing and to form a suction disk that can be used to adhere to objects.

odd

They are the ones that, as their name says, are odd like the orca that has 3 fins

dorsal

A dorsal fin is a fin located on the back of some fish , whales , dolphins , porpoises .

Its main purpose is to stabilize the animal against rolling and to assist in sudden turns. Some animals have developed dorsal fins with protective functions, such as spines or poisons. Many catfish can lock their central dorsal fin spine in an extended position to secure predation or pin them against a crevasse.

Dorsal spines come in a variety of shapes and sizes. And they are famous for showing up as a sign of approaching sharks .

Whales, Dolphins, and Porpoises

Size-wise, a male killer whale ‘s dorsal fin is 18 cm tall. (The female killer whale has it shorter and more curved.) Many (30-100%) male killer whales experience dorsal fin collapse, possibly due to lack of exercise and declining muscle tone, other possible factors may be change in diet, zigzag navigation, reaction with sodium nitrate in pituitary gland then loss of dorsal fin connective tissue (but only about 1% of wild killer whales collapse their dorsal fins.) The dorsal fins of many other whales are relatively small. The bowhead whale Balaena mysticetus does not have a dorsal fin, as an adaptation to its life sailing under the ice.

Whales’ dorsal fins, over time, develop distinctive markings and patterns, helping biologists identify individuals in the field.

Caudal

Sometimes lobed, on the back of the body. It has spiny and simple rays but can also be compound. They are classified in:

• Hypothermia
• Protocerca
• Homocerca
• Difficulty

Anal

They are located in the ventral region, behind the anus.

These fins are outgrowths of skin and in teleost fish they are supported by rays, which are modified scales . In cartilaginous fishes ( Chondrichthyes ), they are supported by filaments of that material.

In aquatic mammals , such as whales and seals , as well as in birds ( penguins ), the fins are transformations of the ends of their extremities ( hands and feet ).

Adipose fin

The adipose fin is a fleshy consistency fin found between the dorsal fin and the caudal fin. It is found in nine orders of teleost fish, in percopsiforms , myctophiformes , aulopiformes , stomiiformes , salmoniformes , osmeriformes , characiformes , siluriformes , and argentiniformes . Its size is very variable.