Q:

What are some different types of fish?

A:

Quick Answer

There are three main types of modern fish: bony fishes, cartilaginous fishes and the bizarre and ancient jawless fishes. Bony fishes are far and away the most common fishes in rivers, lakes and oceans. Jawless fishes, while once very common, are now extremely rare, and only a few species survive.

Continue Reading
What are some different types of fish?
Credit: Kampee Patisena Moment Getty Images

Full Answer

Bony fishes make up most of the fishes in the Earth's aquatic habitats. These creatures exist in a wide array of sizes, from tiny guppies to enormous sunfish. The most characteristic feature of bony fishes is their hard, bony skeleton. However, bony fishes also possess an operculum, a membrane that covers their gills and that both other fish families lack. Another organ unique to bony fish is a depth-regulating structure called the swim bladder.

Cartilaginous fishes include sharks, rays, skates and sturgeon. These fish are characterized by their lack of hard, bony skeletons everywhere except their jaws. Cartilaginous fish have placoid scales, which increase their speed while swimming. Unlike bony fish, cartilaginous fish have internal egg fertilization, and many species are viviparous, giving birth to live young.

Jawless fishes are strange creatures unlike virtually all other living things. They have a bony skull but no jaws or extensive skeleton. They are largely parasites that tear through the host's skin and suck out nutrients. Jawless fish are considered "living fossils," as the vast majority of their relatives went extinct millions of years ago.

Learn more about Fish

Related Questions

  • Q:

    What is a Moses fish?

    A: The Moses sole, or Pardichirus marmoratus, is a fish native to the western Indian Ocean and the Persian Gulf. Reaching a maximum of 12 inches in length, th... Full Answer >
    Filed Under:
  • Q:

    Do all fish lay eggs?

    A: While many fish species are oviparous, not all are; some fish species are ovoviviparous, meaning that eggs are gestated and hatched inside of the female fi... Full Answer >
    Filed Under:
  • Q:

    What are baby fish called?

    A: Baby fish are initially called larvae, then fry and finally fingerlings before they mature into adult fish. Larvae are totally dependent on their yolk sac,... Full Answer >
    Filed Under:
  • Q:

    Do betta fish like light?

    A: Betta fish, also known as Japanese fighting fish, prefer regular periods of light and darkness. This ensures that the fish have a normal sleeping pattern. Full Answer >
    Filed Under:

Explore