May 16, 2006 

Past Episodes
Fish Home

What is a fish?
     A fish is a vertebrate, an animal with a backbone,
which has adapted to life in the water. All fish:

  • have a backbone
  • breathe air, at least part time, using gills
  • are protected by scales
  • have a simple heart
  • have a streamlined body and use fins for swimming

    A fish has a backbone.
What other animals are vertebrates?
     Mammals (such as cats, horses, and elephants), reptiles (such as snakes and lizards), amphibians (such as toads and frogs), and birds also have a backbone.

A Pelican is a vertebrate

How do fish breathe?
     Where the gill is locatedAll animals need oxygen to survive. Fish have special organs called gills. Gills are located on the sides of a fish's head. They are made of thin sheets or membranA seahorse is a fish!es. After fish open their mouth and take in water, they pump it to gills. Fish absorb dissolved oxygen as water passes through gill membranes. Once oxygen is absorbed, water flows out through the gill openings.
Not all underwater animals are fish. Whales and dolphins are mammals. (A mammal is a vertebrate that produces milk to feed their young.) Jellyfish, starfish, and octopus are invertebrates. (Animals without a backbone.)

How many groups of fish are there?

There are three main groups of fishes:

1. jawless fishes like hagfishes and lampreys
2. cartilaginous fishes, like sharks, skates and rays
3. bony fishes, like tuna, eels, and trout

     There are over 25,000 different types, or species, of fish in the world. That's more that all the amphibians, reptiles, birds,and mammals combined! About 200 to 300 new fishes are discovered and named a year. Fish come in all shapes and sizes. The smallest fish is the stout infantfish (Schindleria brevipinguis), measuring about 7 mm (0.3 in) long. Whale sharks can grow to 12m (40 ft) in length. An adult Pacific sturgeon can weigh 400 pounds, reach more than 20 feet in length and live over 100 years.

Idaho Fish and Game LogoTroutFish Identification from Idaho Fish and Game Department, with photos, descriptions, life histories, feeding habits and angling techniques.

Where can fish be found?
     Fish can be found in almost every type of underwater habitat. The Antarctic icefish can survive in water below 0° C (32° F) because their blood contains special anti-freeze chemicals to prevent their body from freezing. Fish are found in hot desert springs, in dried mud in tropical ponds and deep in the ocean.   

     Some live in freshwater, some in saltwater, and some in both!!! Read about Salmon, which live part of their life in freshwater and part in  Salmon

Check out where other native Idaho fish live and what a riffle is! Discover why fish need trees!

Fish Shapes
    In general, fishes are streamlined with a pointed anterior, (snout), and pointed posterior, (rear), anStreamlined body of a fishd a broad propulsive tail. This torpedo-shaped body is typical of the fastest-swimming fishes.
Streamlined means that it is a efficient shape for speeding through the water. Airplanes have a similar streamlined shape for moving through air.

How long do fish live?
     Some fish live for a few weeks and some can live over 50 years.

How do you know the age of a fish ?
      Scientists look at growth rings on scales, and/or ringlike structures found in otoliths (small bones of the inner ear). Read more...

All about Scales
    Scales help protect fish.  There are 4 kinds of scales. Follow this link for photos of scales...
Most fish are colorblind.

Oldest Living Fish
     The Coelacanth is a living fossil that has changed little in its 400 million years on Earth. This ancient fish gives scientists a window into what the Earth was like a long time ago. Read about other fossil fish.

Don't miss the story of this fascinating fish!!!Coelacanth

Follow this link to information about Idaho's Native Fish
IdahoPTV home D4K Dialogue for Kids home