Fishes, Amphibians, Reptiles

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Chapter 11

• Fishes, Amphibians, Reptiles

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Section 1 What is a Vertebrate?

• Characteristics of CHORDATES
• Most are Vertebrates (have a spinal cord)
• Some point in life cycle all chordates have
• Notochord
• Nerve cord that runs down their back (like a
  spinal cord)
• Slits in their throat area

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• NOTOCHORD
• Flexible rod that supports a chordates back
• Lancelet has a notochord its whole life
• All vertebrates have part or all of notochord
  replaced with a backbone
• SLITS in Throat Area
• Also called Pharyngeal slits (or gill slits)
• Fish have them their whole life
• In humans, they disappear before birth

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Characteristics of Vertebrates

• Makes up most chordates
• Has backbone that is part of an internal skeleton
• Backbone spine
• Formed by bones called vertebrae
• Joints in between each bone provide flexibility
• Hole through each vertebrae for spinal cord
• Makes up part of endoskeleton
• Protects internal organs
• Gives body its shape
• Does not need to be replaced
• Location for muscle attachment
• Allows greater growth

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Embryonic Development of Vertebrates
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Keeping Conditions Stable

• Ectotherms
• Fish, reptiles, amphibians
• Animal whose body does not produce much internal
  heat
• Body temperature changes based on temperature of
  the surrounding environment
• Endotherms
• Birds and mammals
• Animals that regulate their own body temperature
• Adaptations including sweat glands, fur/feathers
• Larger variety of suitable living environments

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Section 2 Fishes

• Aquatic vertebrate with fins
• Most are ectotherms
• Obtain oxygen through gills
• Have scales
• Largest group of vertebrates
• Three major groups
• Jawless
• Cartilaginous
• Bony

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Obtaining Oxygen

• Fish opens its mouth and take a gulp of water
• Water moves through throat and then to gills
• Gills contain many blood vessels
• Oxygen diffuses into blood vessels
• Carbon dioxide diffuses out
• Water flows out of slits beneath the gills

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Circulatory System

• Oxygen-rich blood travels through closed system
• Two-chamber heart
• Pumps blood in one loop
• Heart ? gills ? rest of body ? back to heart

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Reproduction

• External fertilization
• Eggs fertilized outside of females body
• Male hovers close to female
• Male spreads a cloud of sperm cells over released
  eggs
• Young develops outside of females body
• Internal fertilization- some sharks, guppies,
  skates
• Eggs fertilized inside of female
• Female gives birth to offspring

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Jawless Fish

• No jaws and no scales
• Mouths designed for scraping, stabbing, and
  sucking their food
• Hagfishes- scavengers w/ large, slimy worm-like
  bodies
• Lampreys- Parasites of other fish

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Cartilaginous Fish

• Skeletons made of cartilage
• Have jaws and scales
• Sharks, rays, skates
• Usually carnivores
• Rays and skates- hunt on ocean floor for
  mollusks, crustaceans, and small fish
• Sharks- attack and eat anything that smells like
  food
• Used jagged teeth arranged in rows
• Only front teeth are used for feeding
• Teeth move forward if front teeth are lost

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Bony Fishes

• 95 of all fish
• Trout, tuna, goldfish
• Skelton made of hard bones
• Scales and a jaw
• Pocket on each side of the head that hold the
  gills
• Swim bladder
• Internal, gas-filled sac
• Helps stabilize fish at different depths

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Section 3 Amphibians

• Means double life
• Beginning of life in water, adult life on land
• Return to water to reproduce
• Ectothermic vertebrate
• Two groups
• Salamanders- keep tails in adulthood
• Frogs and toads- no tail in adulthood

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Reproduction and Development
FROGS SALAMANDERS
Eggs are fertilized externally and develop in water Larvae wriggle out of jelly that coat the eggs TADPOLES frog larvae Begin a free-swimming fish-like life Eggs are fertilized internally Larvae looks like adults During metamorphosis, they lose their gills Changes during metamorphosis are not as dramatic
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Living on Land

• When amphibians become adults, multiple
  adaptations occur
• Lose gills and develop lungs for gas exchange
• Circulatory system changes from single loop with
  a 2-chamber heart to two loops with a 3-chamber
  heart
• Atria- two upper chambers
• Left gets blood from lungs
• Right gets blood from body
• Ventricle- lower chamber
• pumps blood out to both
• lungs and body

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More Adaptations

• Change from herbivores to carnivores
• Develop camouflage to help obtain food
• Develop skeletons and muscular limbs
• Powerful hind-leg muscles for jumping
• Skelton to absorb shock when landing
• Changes to the feet
• Webs to aid in swimming
• Sticky pads for climbing

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Section 4 Reptiles

• Ectothermic vertebrates with lungs and scaly
  skins
• Snakes, lizards, turtles, alligators
• Can spend entire life on land
• Adaptations for water conservation
• Dry, tough skin with scales
• Kidneys filter wastes which are excreting as
  urine
• Amniotic egg prevents embryo from drying out

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Amniotic Egg

• Reptiles exhibit internal fertilization
• Lay eggs on land
• Egg contain shell and 4 internal membranes
• Shell has pores for gas exchange
• 4 Membranes for
• Holding liquid that surrounds embryo
• Holding yolk (food for embryo)
• Holding embryos wastes
• Exchange of O2 and CO2

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Lizards

• Skin with overlapping scales
• Shed their skin and scales as they grow
• 4 legs with claws on toes
• Long tails, external ears, movable eyelids, two
  lungs
• Carnivores that jump at their prey
• Eat frogs, birds, insects depending on size

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Snakes

• Identical skin qualities as lizards
• No legs, streamlined bodies, no external ears or
  eyelids
• Most have only one lung
• Eat small animals like mice
• Use long front teeth for hooking
• Some inject venom via their fangs
• Jawbones can spread apart
• Skull bones can move to swallow large prey

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Alligators and Crocodiles

• Largest living reptiles
• Take care of their young
• Carnivores that hunt at night
• Hunting/Eating adaptations include
• Strong, muscular tails fro swimming
• Jaws with large, sharp, pointed teeth
• Strong jaw muscles for biting down

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Alligator and Crocodile Reproduction

• Care for eggs and newly hatched young
• Female stays near the nest
• Periodically, she will crawl over nest from the
  water to keep it moist
• Once eggs hatch, mother will scoop them up in her
  mouth and carry them away to a safe area in the
  water
• May stay with young up until a year or when they
  can feed and protect themselves

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Turtles

• Reptile covered by protective shell w/ ribs and a
  backbone
• Shells are either hard or soft
• Some can bring head, legs, tail inside for
  protection
• Tortoises land turtles
• Have sharp-edged beak instead of teeth for eating
• Can be carnivores or herbivores

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Extinct Reptiles- Dinosaurs

• Ancestors of reptiles
• Extinct 65 million years ago
• Some may have been endothermic
• Herbivores walked on 4 legs
• Carnivores walked on 2 legs

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Section 5 Vertebrates History in Rocks

• What are Fossils?
• Hardened remains of living things
• Bones, shells, skeletons
• Tissues are replaced by hard minerals
• Found in sedimentary rocks
• Layered rocks containing particles of
• Clay
• Sand
• Mud
• Silt

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More on Fossils

• Paleontologist scientists who study extinct
  organisms by
• Examining fossil structures
• Making comparisons to present-day organisms
• Can determine approximate age by
• Studying sediment layers
• Examining radioactive decay

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Vertebrate Evolution

• Fish- 530 million years ago
• Amphibians- 380 million
• Reptiles- 320 million
• Mammals- 220 million
• Birds- 150 million
• Birds and Mammals are both descendants of reptiles