Fish or Fishes? Multiple individuals of one species are fish. Multiple individuals of more than one species are fishes.

aquatic vertebrates; most with paired fins, scales, and gills.

Kingdom – Anamalia Phylum – Chordata Subphylum Vertebrata Superclass Agnatha (no jaws or paired appendages)

Lampreys and hagfishes do not have true teeth or jaws parasites and scavengers

2 classes 1.Class Myxini – Hagfish are slimy critters Class Cephalaspidomorphi (lamprey) How did they get in the Great Lakes?

Superclass Gnathostomata - fish with jaws (bony and cartilaginous fishes)

2 classes 1. Class Chrondrichthyes (sharks, skates and rays) skeleton of cartilage.

2. Class Osteichthyes - bony fishes, skeletons of bone Blue Gill

Feeding Fishes feed in many ways. They may be herbivores, carnivores, parasites, filter feeders, or detritus feeders. *One fish may feed in several ways, depending on the food available.

Most fish are predators **Variety of teeth types and feeding adaptations Ex 1) Opercula (the “cheeks” protect gills)

Ex 2) Gill rakers (gill modifications that trap plankton in filter feeding fish and screen chunks of food from injuring gills)

Pyloric ceca - folds in intestine to increase surface area for secretion of enzymes and absorption of nutrients

Respiration *Gill Fishes pull water in through the mouth. The water then moves over the gills and out of the body through openings in the sides of the pharynx. k *Some fish may have a simple lung.

Circulation CLOSED circulatory system. It pumps blood in a single loop from heart to gills to the body and back to the heart. The heart consists of two chambers: an atrium and a ventricle.

Excretion *Most fishes get rid of wastes as ammonia *Some wastes diffuse through the gills into the water *Others are removed from the blood by kidneys *Kidneys also help fishes control the amount of water in their bodies

Response Fishes have well-developed nervous systems The cerebrum is primarily involved in smell The cerebellum coordinates body movements The medulla oblongata controls the functioning of many internal organs.

Nervous system continued: Most fishes also have a lateral line system that senses currents and vibrations in the water.

Movement Bony fishes have a gas-filled organ called a swim bladder that keeps them from sinking Paired fins improved control of body movement.

Fish locomotion *Streamlined shape reduces friction *Slime reduces friction *Less gravity pull in water *Fins and body wall push against water *Forked tail fin reduces drag

Reproduction Fishes reproduce in several ways Eggs may be fertilized externally or internally, depending on the species

Ex 1) Oviparous fishes lay eggs The eggs are fertilized, develop and hatch outside the female’s body. (most fish/bony)

Ex 2) ovoviviparous fishes- the internally fertilized eggs develop inside the female. The embryos are fed by yolk in the egg. The young are then "born alive" from the female's body. (sharks/cartilage fish)

Ex 3) viviparous fishes- embryos develop inside the mother. (a few sharks) They get food from the mother's body, not from an egg. They are also born alive.