Fish What is a fish Fish consist of

Fish!

What is a fish? • Fish consist of all gill-bearing aquatic craniate (with a spine and head) animals • They lack limbs with digits (finger or toes). • At 32, 000 species, fish exhibit greater species diversity than any other group of vertebrates.

Body Temperature • Most fish are ectothermic ("cold-blooded"), allowing their body temperatures to vary as temperatures around them change. • Some of the large active swimmers like white sharks and tuna can hold a higher core temperature because of their size.

Body Temperature • Some larger fish, such as tuna have such advanced blood heating systems, they can actually cook their flesh! • When tuna fishermen catch a fish, they must let it swim behind the boat until it gets into shore or the tuna will struggle so much it will cook the flesh along it’s backbone.

Breathing • A gill is a respiratory organ that extracts dissolved oxygen from water, and excretes carbon dioxide. • A gill surface must be kept moist in order for gas exchange to take place. • Some aquatic species that can transition from land to water (such as hermit crabs) can breathe on both land in water as long as the gills are kept moist.

• The more active an aquatic species is, the more need for gills arise. Some species can breathe by absorbing oxygen through the entire surface of their bodies.

• Gills usually consist of thin filaments of tissue or branches that are highly folded to increase surface area. • A high surface area is crucial to the gas exchange of aquatic organisms as water contains only a small fraction of the dissolved oxygen that air does.

• The folds contain blood, from which gases are exchanged through the thin walls. • The blood carries oxygen to other parts of the body. • Carbon dioxide passes from the blood through the thin gill tissue into the water.

Environments • Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high mountain streams (e. g. , char and gudgeon) to deepest oceans (e. g. , gulpers and anglerfish).

Char Fish Gudgeon Gulper Eel Angler Fish

Hagfish • Hagfish are eel-shaped slime-producing marine animals (occasionally called slime eels). • They are the only living animals that have a skull but not a vertebral column (spine). • Along with lampreys, hagfish are jawless and are living fossils.

Lampreys • Lampreys (sometimes also called lamprey eels) are jawless fish and are characterized by a toothed, funnel-like sucking mouth. • While lampreys are well-known for those species which bore into the flesh of other fish to suck their blood, most species of lamprey are not parasitic and never feed on other fish.

Cartilaginous • Cartilaginous fishes are jawed fish with paired fins, scales, a two-chambered heart, and skeletons made of cartilage rather than bone. • Lack ribs, so if they leave water, the larger species' own body weight would crush their internal organs long before they suffocate. • Includes sharks, ray fish and skate fish.

Bony Fish • Group of fish that have bones, as opposed to cartilaginous, skeletons. • It is the largest class of vertebrates in existence today. • They are divided into ray-finned fish and lobe-finned fish.

Fin Types Ray Finned Fish Lobe Finned Fish

Manitoba Fish – Walleye/Pickrel • Walleye is a freshwater fish native to most of Canada and to the northern United States. • In some parts of its range, the walleye is known as the colored pike, yellow pike or pickerel (esp. in English-speaking Canada). • Has been genetically bred with many other fish to make sub-species.