PHYLUM CHORDATA

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PHYLUM CHORDATA Vertebrates Fish, amphibians,
reptiles, birds and mammals
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GENERAL TRAITS OF CHORDATES

• Bilateral symmetry
• Complete digestive system
• Closed circulation with a ventral heart
• Dioecious

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• These traits present during some part/stage in
  their life
• a. Notochord- becomes spine
• b. Dorsal nerve cord- becomes spinal cord
• c. Pharyngeal gill slits
• d. tail

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GENERAL TRAITS OF FISH 1. Streamlined
bodies 2. Mucus covered bodies 3. Paired fins
help with steering balance. 4. Maintain
buoyancy 5. tissues bones not as heavy
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• 6. Respiration- gills water enters mouth,
  passes over gills , gases exchange, water leaves
  w/CO2 thru gill slits.
• 7. Circulation- 2 chambered heart
• a. 1 atrium 1 ventricle
• Path of Blood
• body-atrium-ventricle-afferent
  arteries-gills-efferent arteries-body

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• 8. Nervous- brain spinal cord
• 9. Sensory-
• a. Good sense of smell
• b. Poor eyesight
• c. Lateral Line System- sensory pits in skin
  attached to fluid filled canals under skin can
  detect movement.

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• Excretory System- 2 kidneys
• Osmoregulation- regulation of water ions (salt)
  in body.
• Freshwater fish- water moves into blood due to
  osmosis urinate a lot to remove excess water
• Saltwater fish- water moves out of blood into
  salty water urinate very little to retain water.

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• Digestive System-
• Teeth- modified scales for grasping prey
• Swallow prey whole or in large chunks.
• Large stomach for storing infrequent meals.

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THREE CLASSES OF FISH
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• CLASS AGNATHA
• EX hagfish lamprey
• Jawless fish w/smooth skin- no scales
• No paired fins
• Cartilage skeleton
• Gills open to water
• Fertilization- external
• Oviparous- lays eggs externally

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• Lamprey-
• a. Suckerlike mouth
• b. Teeth rasping tongue scrape scales off
  host.
• c. Suck blood of fish

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• Hagfish-
• a. Live buried in sand mud
• b. Mouth with 4 pairs of tentacles
• c. Enter dying/dead fish thru mouth
• d. Eat contents of body, leaving sack of skin
  bones
• e. Secretes green slimy mucus to deter predators

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• CLASS CHONDRICHTHYES
• EX sharks, skates, rays
• jaws
• Paired fins
• Cartilage skeleton
• Gills open to water- gill slits
• Dermal placoid scales- dermal denticles
• a. Point backward- reduces friction in water
• b. feels like and used to be used as sandpaper.
• 7. Buoyancy- oily livers

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8. Special Digestive Adaptations a. Teeth in
rows 1. ratchet forward when one is lost. 2.
New row of teeth develop every 7-8 days b.
Rugae- folds in stomach that expand to hold
large meals c. Spiral valve- increases
absorption of nutrients (like human villi)
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9. Special Respiratory Adaptations a. Ram
Ventilation- some sharks 1. Swim with mouth
open to force water into mouth over gills.
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b. Spiracles- holes behind eyes 1. Used for
breathing while eating.
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LABEL THE DIAGRAM OF THE EXTERNAL
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10. Special Sensory Adaptations a. Lateral
Line system b. Ampullae of Lorenzini- 1.
pits in snout that detect impulses or electrical
currents in water. 2. Used to find
prey, mates, identify predators. 3.
Helps sense in murky or turbulent water
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11. Fertilization- internal a. Males have
penis- like structure called clasper for
inseminating female.
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• b. Development of eggs
• 1. Oviparous- lays eggs
• 2. Ovoviviparous- eggs hatch inside mother
• No placenta so babies that have hatched sometimes
  eat other eggs /or siblings that have hatched.
• EX Great whites nurse sharks
• 3. Viviparous- Pups are attached to mother by
  placenta
• 1. EX bull shark, mako, whale shark,
  hammerheads

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12. Smallest- dogfish shark (1 meter) 13.
Largest- whale shark (10 meters filter feeds)
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14. Skates rays find food along bottom.
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Male shark
Female shark
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• CLASS OSTEICHTHYES
• EX tuna, bass, bluegill, seahorse
• Bony fish
• Jaws
• Paired fins
• Bony skeletons
• Gill openings covered with operculum- muscular
  plate that pulls water into mouth.

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• Buoyancy- swim bladder
• a. Increase air- fish rises
• b. Decrease air- fish sinks
• Special Sensory Adaptations
• a. Ossicles- pick up vibrations in water for
  hearing

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• Reproduction
• a. Fertilization- external
• b. Oviparous
• c. Males create nest. Females lay eggs.
  Males fertilizes eggs. Sometimes female
  protects eggs until hatching.
• d. Spawning- return to river born in to
  reproduce (salmon)

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10. Scales- a. Can be used to identify
fish b. Can estimate age of fish with rings
(annuli) on scales. 1. Cosmoid 2.
Ganoid 3. Cycloid 4. Ctenoid
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Pay close attention to these pictures so that
when you are dissecting the shark you recognize
organs! You will label a picture of the internal
anatomy of the shark at the end of these notes!
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• Shark skin was once used for
• a. Sand paper b. Clothing c. Writing
  utensils
• Bony fish belong to the class
• a. Agnatha b. Chondrichthyes c. osteichthyes
• Sharks reproduce using ___ fertilization
• a. External b. internal
• Which type of fish has placoid scales?
• a. Bass b. Stingray c. hagfish
• The structure in bony fish that maintains
  buoyancy is
• a. Operculum b. Swim bladder c. Oily liver