1. Fish and Amphibians
CHAPTER 30

2. Fish
SECTION 2

3. What is a Fish?
Aquatic vertebrates
Most have paired fins for movement, scales for
protection, and gills for exchanging gases

4. Evolution of Fish
First Fish (510 mya) – jawless with armored bodies
The Age of Fish (505 – 410 mya) – evolution of jaws
and paired fins
The Rise of Modern Fish
 Two major groups that live today
 Fish with skeletons made of cartilage
 Fish with skeletons made of true bone

5. Form and Function in Fish
Feeding
 Every mode of feeding is seen in fish
 Some fish exhibit more than one type of feeding
 Food is digested internally Esophagus
Stomach
Mouth

6. Form and Function in Fish
Respiration
 Most exchange gases using gills
Gills

7. Form and Function in Fish
Circulation
 Closed circulatory system that pumps blood in a single loop
around the body

8. Form and Function in Fish
Excretion
 Fish eliminate nitrogen waste in the form of ammonia
 Some wastes diffuse through the gills and others through the
kidneys
Kidney

9. Form and Function in Fish
Response
 Well developed nervous systems organized around a brain
 Fish that are active during the day have well developed eyes
Brain

10. Form and Function in Fish
Movement
 Many bony fish have a gas filled swim bladder that allows them
to adjust their buoyancy
 Move by contracting muscles on either side of the backbone
Swim bladder

11. Form and Function in Fish
Reproduction
 Eggs fertilized either internally or externally, depending on the
species
 Oviparous – eggs hatch outside the mother’s body
 Oviviparous – eggs stay inside the mother’s body
 Viviparous – embryos stay inside the mother’s body

12. Groups of Fish
Groups of Fish
 Jawless fish
 Cartilaginous fish
 Bony fish

13. Jawless Fish
No true teeth or jaws
Skeletons are made of fibers and cartilage
Lack vertebrae, keep their notochords as adults
Two classes: lampreys and hagfish

14. Sharks and their Relatives
Class Chondrichthyes contains sharks, rays, skates,
sawfishes, and chimaeras
Skeletons built entirely of cartilage

15. Bony Fish
Class Osteichthyes
Skeletons made of bone
Almost all are ray-
finned fish

16. Ecology of Fish
Most fish spend their
entire lives in either fresh
or salt water
Some migrate to breed
 Anadromous – live in
salt water but migrate to
freshwater to breed (Ex:
salmon)
 Catadromous – live in
freshwater but migrate to
saltwater to breed (Ex:
North American Eels)

17. Amphibians
SECTION 3

18. What is an amphibian?
An amphibian is a vertebrate that, with some
exceptions:
 lives in water as a larva and on land as an adult
 breathes with lungs as an adult
 has moist skin that contains mucous glands
 lacks scales and claws

19. Evolution of Amphibians
The first amphibians appeared in the late Devonian
Period, about 360 million years ago
The transition from water to land required that the
terrestrial vertebrates had to:
• breathe air
• protect themselves and their eggs from drying out
• support themselves against the pull of gravity

20. Amphibian Adaptations
Lungs
Pelvic Girdle
Leg Bones:
The legs of a land
vertebrate must be Skin: The skin and the lining of
strong enough to hold its the mouth cavity of many adult
weight. amphibians are thin and richly
supplied with blood vessels.
Watery mucus is secreted by
glands in the skin.

21. Form and Function in Amphibians
Feeding
Mouth Esophagus
Tadpoles – filter feeders
or herbivores that graze
on algae
Adults – almost entirely Stomach
carnivorous

22. Form and Function in Amphibians
Respiration
Larval amphibians – gas exchange through skin and
gills
Adults – usually gas exchange occurs through lungs
Circulation
Circulatory system forms a double loop circulating
oxygen-rich and oxygen-poor blood throughout the
body

23. Form and Function in Amphibians
To body, To body,
lungs lungs Heart
and skin
From and skin From Lung
Body Lung
Kidney
s
Ureter
Urinary
bladder
Left Cloaca
Right atriu
atriu m
m
Ventricle

24. Form and Function in Amphibians
Excretion
Kidneys filter wastes from blood
Urine exits through the cloaca
Reproduction
Most species, male fertilizes egg externally in water
Some fertilize eggs internally
Most abandon their eggs after laying them, but a few
take care of their young

25. Frog Metamorphosis

26. Form and Function in Amphibians
Movement
Larva wiggle their bodies to move
Adults have 4 limbs to walk, run, or jump
Response
Well developed nervous systems
 Nictitating membrane helps keep eyes moist
 Tympanic membranes allow them to hear
 Lateral line helps to sense water movement

27. A Frog’s Sense Organs

28. Groups of Amphibians
Three groups:
 Salamanders
 Frogs and toads
 Caecilians

29. Salamanders
Long bodies and tails
Most have four legs
Adults and larvae are carnivores
Adults live in moist woods where they tunnel under
rocks and rotting logs

30. Frogs and Toads
Frogs and toads have the ability to jump
Frogs tend to have long legs and make lengthy jumps
Toads have relatively short legs and are limited to
short hops
Frogs are more closely tied to water

31. Caecilians
Legless animals that live in water or burrow in moist
soil or sediment
Feed on small invertebrates such as termites
Many have fishlike scales embedded in their skin

32. Ecology of Amphibians
The global amphibian population is declining
It is possible that amphibians are susceptible to a
wide variety of environmental threats