chapter 18 fishes. characteristics phylum: craniata (describes the skull that surrounds their brain...
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Chapter 18
Fishes
Characteristics
• Phylum: Craniata (describes the skull that surrounds their brain
• Much evolution occurred in freshwater
• Much evolution involved the movement of fish between fresh and marine environments
• Over 41% of fish live in freshwater even though only small percentage of the Earth’s water resources is freshwater
Subphylum Hyperotreti: Hagfishes
• 20 species• Heads are supported by
cartilage and brains enclosed in a fibrous sheath
• Retain a notochord• 4 pairs of sensory tentacles
surrounding their mouths• Cold water marine habitats • Most primitive group in the
craniata• Live buried in the sand and
mud• Feed off of soft bodied
invertebrates and scavenge dead and dying fish
• Slimy skin
Subphylum Vertebrata: Ostracoderms
• Extinct agnathans• Had bony armor as a
defense• Bottom dwellers• Filter feeders
Subphylum Vertebrata: Hyperoartia-Class Cephalaspidomorphi
• Lampreys• Found in freshwater and
marine environments• Prey on other fish and
their larvae as filter feeders
• Mouth of an adult lamprey is suckerlike with lips that have sensory attachments
• Have salivary glands with anticoagulant secretions and feed mainly on the blood of their prey
Lampreys
• Adult lampreys live in the ocean or the Great lakes, at the end of their lives they migrate to freshwater to spawn
• They build spawning nests in shallow water, a female attaches to a rock with her mouth, male use their mouth to attach to the female head and wrap themselves around the female
• Eggs are shed in batches and fertilized externally and then covered in sand
Gnathostomata
1. 2 important evolutionary developments
– Jaws: allowed for more efficient gill ventilation
– Paired appendages: used to counteract the tendency to roll during locomotion and control the pitch of the the swimming fish
2. 2 classes: cartilaginous and bony fish
3. Contain the armored fish which are extinct and acanthodians which are also extinct
Class Chondrichthyes
• Includes sharks, skates, rays and ratfishes
• Most are carnivores or scavengers
• Have biting mouthparts and paired appendages
Subclass Elasmobranchii
• About 820 species
• no swim bladders
• Cartilaginous skeleton
• Born with full sets of teeth
Tiger Sharks
• Found in tropical and temperate waters
• Can grow up to 16 ft.
• Solitary, nocturnal
• Wide spectrum of food
• http://www.discovery.com/tv-shows/shark-week/videos/tiger-sharks-snack-on-birds.htm
Whale Shark
• Slow moving filter feeding shark
• Largest: 41 feet and 47000 pounds
• Found in warm oceans
• Life span of 70 years
Whale Shark
• Feed mainly on plankton
• Docile
• Does not pose a threat to humans
• http://www.youtube.com/watch?v=uQrBwN39LJI
Hammerhead Shark
• Utilize electroreception
• http://video.nationalgeographic.com/video/worlds-deadliest/deadliest-hammerhead-shark
Distribution
Hammerhead sharks Tiger sharks
Stingray
• http://video.nationalgeographic.com/video/stingray
• http://video.nationalgeographic.com/video/sting-rays-doubilet?source=searchvideo
Subclass Holocephali
• About 30 species
• Have an operculum: gill cover
• Lack scales
Class Osteichthyes
• Bony fish
• Have swim bladders: an internal gas filled organ that contributes to the buoyancy of fish
Subclass Sarcopterygii
• Have muscular lobes associated with fins and use lungs in gas exchange
• They survive stagnation by breathing with lungs but normally use gills
Coelacanths
• Rare order of fishes that were thought to have been extinct but rediscovered in 1938
Osteolepiforms
• Prehistoric lobe finned fish
• Extinct
Subclass Actinopterygii
• Ray finned fishes
• Possess swim bladders
• Sturgeons, paddlefishes
Sea Horses
• 54 species• Class actinopterygii• Female deposits up
to 1500 eggs in a male seahorses pouch who then carries them for up to 45 days till they emerge from pouch
Sea horses
• http://www.youtube.com/watch?v=C1XYg4km7Yk
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