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CHORDATES: FISHES (JAWLESS, BONY AND CARTILAGINOUS CREATURES). Barbara Leary and Amy Vallis AP Biology Ms. Bergman April 8, 2011. BODY STRUCTURE AND COVERING. BONY FISH ( Teleosts ) Scales are flatter covered by thins layers of skin and mucus making them slippery
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Barbara Leary and Amy Vallis
April 8, 2011
CARTILAGINOUS FISH (Elasmobranchs)
-No ossified bone
-No swim bladder (must be in constant motion)
-Scales project through the skin and
Fins maintain the stability and maintain the direction of the fish.
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 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.
Spawning 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.
-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
Fish during spawning season (Salmon especially)
Male gonopodium compared to regular female fins
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.
MODE OF DEVELOPMENT
-Hagfish (slime eels)
-Rays and Skates