CHORDATES:

FISHES (JAWLESS, BONY AND CARTILAGINOUS

CREATURES)

Barbara Leary and Amy VallisAP Biology

Ms. BergmanApril 8, 2011

BODY STRUCTURE AND COVERINGBONY FISH (Teleosts)-Scales are flatter covered by thins layers of skin and mucus making them slippery-Body cavity with air filled bladder (used to float) beneath spinal columnJAWLESS FISH-covered in skin, not epidermal or dermal cells

CARTILAGINOUS FISH (Elasmobranchs)-No ossified bone-No swim bladder (must be in constant motion)-Scales project through the skin and are rough

Fins maintain the stability and maintain the direction of the fish.

JAWLESS FISH: Lampetra fluviatilis

CARTILAGINOUS FISH

BONY FISH

GAS EXCHANGE • Gills found in other creatures besides fish such as:• Mollusks• , annelids, • crustaceans, • echinoderms, • vertebrates.

•Gills must be very efficient to meet the respiratory demands of aquatic animals. •Fish gills, for example, can extract more than 80% of the oxygen dissolved in water.

GAS EXCHANGE CON’T

Fish gills are made of numerous suspended curtains of tissue, called filaments, that increase their respiratory surface area. Gill tissue is permeated with many small water-bearing channels surrounded by capillaries. Because the water channels and capillaries are so close to one another, O2 and CO2 readily diffuse between the blood and water.

FISH HEARTS-Simplest vertebrate hearts (single-circuit circulation):-Two main chamber:s

- Thin walled atrium- Muscular ventricle

Process: Atrium pumps blood into the ventricle which pumps blood into the copus which pumps the blood to the gills to oxygenize it and return it to the atrium.

MODE OF FERTILIZATIONFish can use both internal and external fertilization, but external is more common.97% of fish a oviparous (developing outside the mother’s body with no nourishment), while the rest are the opposite—viviarous.

EXTERNALSpawning occurs-release of egg and sperm in aquatic animals-Female fish grow thousands of unfertilized eggs inside their body for several weeks to increase chance of fertilization.-Once produced, they are then laid in a safe place for male fish to fertilize them with their semen.-This allows conception to take place, and immediately the fish eggs start to become fish.

INTERNAL-Modified fin- gonopodium- used to insert itself in the sex opening of the female and sperm is preserved in the oviduct to be used when they please

INTERNAL TEMP. REGULATION

•Most fish are ectotherms (cold blooded), as all of their heat comes from the surrounding water. However, some are homeotherms (warm-blooded) because their temperature is very stable.•This can be due to their location, type of water, how they breed, etc..

Cold-blooded

Warm-blooded

INTERNAL Male gonopodium compared to regular female fins

EXTERNALFish during spawning season (Salmon especially)

MODE OF DEVELOPMENT•The most common reproductive strategy for fish is known as oviparity, in which the female lays undeveloped eggs that are externally fertilized by a male. and the eggs are then left to develop without parental care.  •A few fish, notably the rays and most sharks use ovoviviparity in which the eggs are fertilized and develop internally. However the larvae still grow inside the egg consuming the egg's yolk and without any direct nourishment from the mother.

•In certain rare scenarios, some fish such as certain sharks, with the egg being fertilized and developed internally, but with the mother also providing direct nourishment.

SUBGROUPS

JAWLESS-Hagfish (slime eels)-Lamprey Eels

CARTILAGINOUS-Sharks-Rays and Skates

BONY-Lobe-finned-Ray-finned

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