MARINE FISHES [Autosaved].pptx

marine fishes

1. MARINE FISHES BIO 421-422

2. Marine Fishes Jawless Fish Cartilaginous Fish Bony Fish 20XX Presentation title 2

3. Jawless fish 3 Hagfish Lamprey Modern jawless fish include the hagfish and lampreys which both still lack jaws and paired appendages . Their skeletons are entirely composed of cartilage and their bodies lack scales .

4. 4 Hagfish – also known as slime eels deep-sea bottom dwelling fishes found throughout the world. inhabit depths of more than 600 m, often in the tropics, although they are sometimes found in the shallower seas. Hagfish feed using two dental plates, containing horny cups, with which grab their prey and draw it into their mouth. They feed primarily on small invertebrates but may also be scavengers on larger carcasses found on the sea floor.

5. 5 Lampreys -Lampreys can inhabit both salt and freshwater. -They have a rudimentary vertebral column. -Their mouthparts consist of an oral disk and rasping tongue covered with toothlike plates of keratin Several species use these plates to grasp prey, rasp a hole in the victim and suck out the tissue and fluids. Marine lamprey species spend their adult life in the open oceans but have been found to migrate to freshwater to spawn, where they die shortly afterwards.

6. Cartilaginous Fishes 6 Modern cartilaginous fishes include sharks , skates , rays and chimaeras , which possess both jaws and paired fins. Their skeletons are composed entirely of cartilage, although this is often strengthened by calcium salts. The bodies of cartilaginous fishes are covered in placoid scales. They have several rows of teeth on their jaws. There are two major groups of cartilaginous fishes: the elasmobranchs (sharks, skates and rays) and the holocephalans (chimaeras and ratfish).

7. 7 Sharks Sharks typically have streamlined bodies and are excellent swimmers, using their strong body in a sideways sweeping motion. Sharks do not possess swim bladders, and so will sink if they stop swimming. To counteract this buoyancy problem, their livers contain large quantities of an oily substance called squalene, which helps to offset the shark’s high density. Their heterocercal caudal fin and enlarged pectoral fins also help maintain position in the water column.

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9. Myths ABOUT SHARKS 9 1. Sharks are man-eating, blood-thirsty creatures. False. Sharks do not naturally hunt humans. Most occurrences of a shark attack are due to poor water visibility or curiosity rather than predatory intentions. 2. You are more likely to be struck by lightning, or killed in a car accident than attacked by a shark. True. 3 . Sharks can detect a single drop of blood in the ocean. False.

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11. 11 Seatwork #1 Which shark is the biggest of all the species? Which shark is the biggest meat-eating shark? Which shark is the fastest? Which shark is the scariest ever? Which shark is the most dangerous? Which shark lays eggs? Which shark is the smallest?

12. 12 Skates and Rays Skates and rays differ from sharks by having flattened bodies with greatly enlarged pectoral fins, reduced dorsal and caudal fins and no anal fins. Their eyes and spiracles (openings for the passage of water) are located on the top of their heads while their gill slits are on the ventral side, allowing debris-free water to enter through the spiracles and be passed out over the gills. Most skates and rays are adapted to live a benthic lifestyle where they feed on invertebrates (e.g. crustaceans and mollusks) using their specialized crushing teeth.

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14. 14 Chimaeras Chimaeras are generally bottom dwellers found in a variety of habitats from the shallows to deep waters. They include species such as the ratfish, rabbitfish and spookfish . Unlike other cartilaginous fishes, their gills are covered with an operculum and water is taken in through the nostrils before being expelled over the gills. Chimeras are oviparous, producing large eggs in leathery cases. They feed on a variety of prey, including crustaceans, mollusks and fish, crushing them between oral plates (instead of teeth).