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
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
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)
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
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
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