Chapter 15
Fish, Amphibians, and Reptiles
Section 15.1: Fish (p.400-401)
Vertebrate Characteristics
Traits of Chordates
 Vertebrate animals belong to the phylum Chordata
 3 subphyla, largest is vertebrates
 2 smaller subphyla are made up of tunicates (sea
squirts) and lancelets
 Tunicates
 Sessile
 Filter feeders
 Lancelets
 Free swimming
 Filter feeders
 Most times buried in sand w/heads sticking out
 What do tunicates and lancelets have in common
with vertebrates?
 Notochord- flexible, rodlike structure along
dorsal side (vertebrates – becomes backbone)
 Dorsal hollow nerve cord- tubular bundle of
nerves that lies above the notochord
(vertebrates – becomes spinal chord and brain)
 Gill slits – paired openings located in throat
behind the mouth
What is a vertebrate?
 Named for column of bones called vertebrae that
encloses the dorsal nerve cord
 Endoskeleton – supports and protects internal
organs and is where muscles are attached
 Most are ectotherms – animal where internal body
temperature changes with temp of surroundings
 Endotherms – animals with constant internal body
temperature (birds and mammals)
What is a fish?
- Three classes of fish
- More than 30,000 species of fish (more than all other
species of invertebrates)
Fish Adaptations
 Ectotherms
 Gills for breathing
 Fins – used for steering, balancing and moving
 Scales – hard, thin, overlapping plates made of bone
that cover the skin and protect the fish’s body
 3 classes: jawless fish, cartilaginous fish and bony
fish
Origins of Fish
 Evolved from small, soft-bodied, filter-feeding
organisms (like lancelets)
 Fossils of jawless fish from 450 million years ago
 Placoderms fossils found 390 million years ago
 First bony fish appeared 190 million years ago
Jawless Fish
 Class Agnatha – lampreys (fresh and salt water) and
hagfish (salt water)
 Agnatha – means jawless
 Round mouths and long, tubelike bodies covered in
slimy skin with no scales
 Flexible bodies made of cartilage – tough, flexible
tissue (like tip of nose and ears on humans)
 Lampreys use mouth to cut into fish and feed on its
blood and body fluids
Cartilaginous Fish
 Sharks, skates and rays
 Class Chondrichthyes
 Chondros means cartilage and ichthyes means fish
 Skeletons made of cartilage
 Movable jaws and scales
Bony Fish
 Class Osteichthyes
 Osteon means bones
 Skeletons made of bone
 95% of all species of fish belong to this class
 Gills have a gill cover
 Females release eggs into water
 Males swim over eggs and release sperm
 Spawning – external fertilization
Buoyancy
 Swim bladder – air sac that helps control buoyancy
 Swim bladder allows fish to adjust its density so it
can rise or sink
 Glands regulate gas content
 Deep-sea fishes often have oil rather than gases
 Bottom-dwellers have no swim bladders
Kinds of Bony Fish
 Three groups – lobe-finned fish, lungfish and rayfinned fish
 Most are ray-finned fish
 Lobe-finned: fins are lobelike and fleshy
 Lungfish: have lungs and gills which allows fish to live
in shallow waters (cover themselves with mucus and
mud)
 Ray-finned: long, thin bones covered with skin
Section 15.2: Amphibians (p.408-412)
What is an amphibian?
 Amphibios – means double life
 Ectothermic vertebrates
 Live in water and on land
 Moist skin that is smooth, thin, and without scales
 Carbon dioxide and oxygen exchanged through skin
and lining of the mouth
 Small, simple, saclike lungs for breathing
Amphibian Adaptations
 During winter, bury themselves in mud or leaves
 Hibernation – period of inactivity in winter
 Estivation – period of inactivity during hot, dry
summer months
 Strong skeleton made of bone
 Most lay their eggs in water
 Eggs hatch into larvae that live in water
Origins of Amphibians
 Evolved from lobe-finned fish about 350 million
years ago
 For 100 million years or more, amphibians were the
dominant land animals
Frogs, Toads, and Salamanders
 Have short, broad bodies with no neck, no tail, and
four legs
 Frogs
 Strong, longer hind legs are for jumping
 Shorter, front legs are for swimming and
jumping
 Eyes and nostrils on top of the head – let frogs
see and breathe under water
 Frogs use tongue to catch insects
 Tympanic membranes vibrate to response to
sounds and are used to hear
 Toads
 Breed in water
 Thick, warty skin
 Eat invertebrates (spiders, worms, etc.)
 Glands on back that secrete poison
 Salamanders and newts
 Found under dead leaves and rocks to avoid
heat from the sun
 Salamanders and newts use sense of smell and
vision to feed on worms, crustaceans, and
insects
 Breed on land
Amphibian Metamorphosis
 Series of changes larva go through to become adult
 Most have 2 stage life cycle
 Larval stage that lives in water
 Adult stage that lives on land
 Growth rate and length of time as larva depends on
 Species
 Water temperature
 Available food
 Bullfrogs may take a year
 Spadefoot takes about two weeks
 Mud puppies never grow out of larval stage
Section 15.4: Reptiles (p.416-420)
What is a reptile?
 Ectothermic vertebrate with dry, scaly skin
 Class Reptilia includes: lizards, snakes, turtle,
crocodiles, alligators and extinct dinosaurs
 Thick, dry, waterproof skin covered with scales for
protection
 Four legs with claws for moving, digging, climbing,
and running (except snakes)
 Live on land
 Need water for reproduction
Variety in Reptiles
 Vary in size, shape and color
 Live on every continent except Antarctica
 Live in all the oceans except those in polar regions
 Breathe with lungs
 Hearts have 3 chambers
Development of Amniotic Egg
 Eggs of reptiles are fertilized internally in females
 After fertilization, females secrete a leather shell
around each egg and lays the eggs on land
 Amniotic egg contains membranes to protect and
cushion the embryo and get rid of wastes
 Yolk supplies food for the embryo
 Pores in the shell allow oxygen and carbon dioxide to
be exchanged
 Looks like a young adult when hatched
Origins of Reptiles
 First appeared in the fossil record nearly 280 million
years ago
 First reptiles called cotylosaurs
 By the end of Triassic period, reptiles began to
dominate the land
 The Mesozoic era is considered the Age of the
Reptiles
Modern Reptiles
 Descended from cotylosaurs
 3 orders of reptiles: turtles; crocs and alligators; and
lizards and snakes
Turtles
 Found on almost every continent and in most of the
world’s oceans
 Body covered by hard shells on top and bottom
 Withdraw into their shells for protection
 Have no teeth
 Use their beaks to feed on insects, worms, fish and
plants
Crocodiles and Alligators
 Among largest living reptiles
 Order Crocodilia




Found in or near tropical climates
Crocodiles have long, slender snouts
Crocodiles are more aggressive than alligators
Alligators have broad snouts
Lizards and Snakes
 Make up the largest group of reptiles
 Lizards have movable eyelids, external ears and legs
with clawed toes on each foot
 Lizards eat reptiles, insects, spiders, worms, and
mammals
 Snakes “hear” vibrations in the ground
 Snakes are meat-eaters
 Some snakes constrict, others inject prey with
venom
Maternal Care in Reptiles
 Most fish, amphibians, and reptiles show little or no
care for their eggs once laid
 Crocodiles stay near their nests
Chapter 15
Fish, Amphibians, and Reptiles
Section 15.1: Fish (p.400-401)
Vertebrate Characteristics
Traits of Chordates
 Vertebrate animals belong to the
 3 subphyla,
 2 smaller subphyla are made up of tunicates (sea
squirts) and lancelets
 Tunicates

 Filter
 Lancelets
 Free
 Filter s
 Most times buried in sand
 What do tunicates and lancelets have in common
with vertebrates?
 Notochord Dorsal hollow nerve cord(vertebrates – becomes spinal chord and brain)

– paired openings located in
throat behind the mouth
What is a vertebrate?
 Named for column of bones called
 Endoskeleton – supports and protects
 Most are ectotherms – animal where internal body
 Endotherms – animals with
temperature (birds and mammals)
What is a fish?
- Three classes of fish
- More than 30,000 species of fish
Fish Adaptations

 Gills for
 Fins – used for
 Scales – hard, thin, overlapping plates made of bone
that cover the
 3 classes:

Origins of Fish
 Evolved from small, soft-bodied, filter-feeding
organisms
 Fossils of
from 450 million years ago
 Placoderms fossils found
years ago
 First bony fish appeared
years ago
Jawless Fish

– lampreys (fresh and salt water) and
hagfish (salt water)
 Agnatha –
 Round mouths and long, tubelike bodies covered in
 Flexible bodies made of cartilage –
 Lampreys use mouth to cut into fish and feed on its
Cartilaginous Fish
 Sharks, skates and rays
 Class
 Chondros means
 Skeletons made of
 Movable jaws and
Bony Fish
and ichthyes means








Class Osteichthyes
Osteon means
Skeletons made of bone
of all species of fish belong to this class
Gills have a
Females release eggs
Males swim over eggs and
Spawning –
Buoyancy
 Swim bladder – air sac that helps
 Swim bladder allows fish to adjust its density so it
can
 Glands regulate
 Deep-sea fishes often have
 Bottom-dwellers
Kinds of Bony Fish
 Three groups –
 Most are ray-finned fish
 Lobe-finned: fins are
 Lungfish: have lungs and gills which allows fish to live
in shallow waters
 Ray-finned: long, thin bones covered
Section 15.2: Amphibians (p.408-412)
What is an amphibian?
 Amphibios – means

 Live in water and
 Moist skin that is
 Carbon dioxide and oxygen exchanged through skin
and
 Small, simple, saclike
Amphibian Adaptations
 During winter, bury themselves in
 Hibernation – period of
 Estivation – period of
 Strong skeleton made of
 Most lay their eggs in
 Eggs hatch into larvae that
Origins of Amphibians
 Evolved from
about 350 million years
ago
 For 100 million years or more, amphibians were the
Frogs, Toads, and Salamanders
 Have short, broad bodies with no neck, no tail, and
four legs
 Frogs
 Strong, longer
 Shorter, front legs are for
 Eyes and nostrils on top of the head – let frogs
 Frogs use tongue to catch
 Tympanic membranes vibrate to response to
 Toads
 Breed in
 Thick,
 Eat
(spiders, worms, etc.)
 Glands on back that secrete
 Salamanders and newts
 Found under
to avoid heat
from the sun
 Salamanders and newts use
to feed on worms, crustaceans, and insects
 Breed on
Amphibian Metamorphosis
 Series of changes larva go through to become adult
 Most have

that lives in water

that lives on land
 Growth rate and length of time as larva depends on

 Water
 Available
 Bullfrogs may take a
 Spadefoot takes about
 Mud puppies never grow out of
Section 15.4: Reptiles (p.416-420)
What is a reptile?
 Ectothermic vertebrate with
 Class Reptilia includes: lizards, snakes, turtle,
crocodiles, alligators and extinct dinosaurs
 Thick, dry, waterproof skin covered
 Four legs with claws for
(except snakes)
 Live on
 Need water for
Variety in Reptiles
 Vary in




Live on every continent
Live in all the oceans except those in
Breathe with
Hearts have
Development of Amniotic Egg
 Eggs of reptiles are
 After fertilization, females secrete a
 Amniotic egg contains membranes to protect and
cushion
 Yolk supplies
for the embryo

in the shell allow oxygen and carbon
dioxide to
 Looks like a young adult when
Origins of Reptiles
 First appeared in the fossil record nearly 280 million
years ago
 First reptiles called
 By the end of Triassic period, reptiles began to
 The Mesozoic era is considered the
Modern Reptiles
 Descended from
 3 orders of reptiles:
Turtles
 Found on almost every continent and in most of the
world’s oceans
 Body covered by
 Withdraw into their shells
 Have no
 Use their beaks to feed on
Crocodiles and Alligators
 Among
living reptiles
 Order Crocodilia
 Found in or near
 Crocodiles have
 Crocodiles are more aggressive than
 Alligators have
Lizards and Snakes
 Make up the largest group of
 Lizards have movable
 Lizards eat reptiles, insects, spiders, worms, and
mammals
 Snakes
vibrations in the ground
 Snakes are
 Some snakes
Maternal Care in Reptiles
 Most fish, amphibians, and reptiles show
 Crocodiles stay near