1. Fishes and Amphibians
Chapter 26-2

2. Characteristics of Fish
Phylum Chordata (have a spinal cord)
Have a notochord(flexible supporting rod that runs along the dorsal surface of the body), hollow dorsal nerve cord,(on the back side of the body that conducts impulses) and pharyngeal slits(structure that appears in pairs in throat region)
The notochord is replaced by a backbone (vertebral column)

3. Definition of a fish Aquatic vertebrates Scales Fins Pharyngeal slits
Some excpetions: (some fish do not have scales)

4. Groups of fish Jawless (Agnaths) Bony (Class Osteichthyes)
Cartilaginous (Chondrichthyes)- over 97% of all living fish today belong to this class

5. How did fish evolve? They are the first vertebrates to evolve.
First fish were jawless, body covered with bony plates (540 mya)
Major adaptive radiation occurred:
Jawless with little armor (extinct)
Armored but in a new form
Some had jaws that advanced them in feeding

6. More about evolution… Jawless fish are limited to filter feeding
Jaws can crush, nibble, and be used in defense
Fish also evolved the paired pectoral fins and pelvic fins which gave them better control of movement in water.
The fins later evolved into limbs and shoulder bones of terrestrial vertebrates

7. Fish Anatomy Fish have evolved many adaptations to many environments
Feeding: every form of feeding
Sawfish kill and stun prey
Parrotfish have teeth fused into a beak to bite coral
Archerfish spits drops of water and shoots down insects
Most fish swallow the prey whole

8. Digestion MouthEsophagusStomach (partially broken down)
Pyloric ceca(little pouches that break down food)
Intestines (complete digestion and absorbtion)

9. Respiration
Most use gills that are located on either side of the pharynx (connects mouth to digestive tract)
Many capillaries to increase surface area for gas exchange
Water enters the mouthover the gill filamentsslits in the sides of the pharynx
Some use the swim bladder (organ used to control the depth of swimming) as lungs (ex. Siamese fighting fish)

10. Internal Transport Closed Circulatory System Heart has 2 chambers
O2 poor blood collects in the atrium
Then pumps into the ventricle
Blood is pumped through the aorta to the gills
Then blood is transported to the rest of the body
Collects in Sinus Venosus (veins) then re-enters the atrium

11. Excretion Nitrogenous waste in the form of NH4
Through gills in the water
Kidneys filter blood
Also control the amount of water in the body (salt-water fish need to keep water and fresh-water fish need to get rid of excess water)

12. Response Fish have a well-developed nervous system
Olfactory bulbs and Cerebrum at front of head- smell (chemoreceptors)
Optic lobes- sight
Cerebellum-movement
Medulla-internal organs and balance
Lateral- line detect motion

13. Internal Anatomy

14. Reproduction Separate sexes- male and female Oviparous-lay eggs
Ovoviviparous-eggs develop within female
Viviparous- true live-bearing

15. Jawless Fish No backbones, just notochord
Lampreys- parasitic, large sucking disc at the head to latch on to prey
Hagfishes-pinkish-grey wormlike bodies
No eyes, feed on dead or dying fish
Secrete a lot of slime, have 6 hearts, and sometimes tie themselves in a knot!

16. Hagfish

17. Lamprey

18. Sharks and Relatives Endoskeleton made out of cartilage Tough scales
3,000 teeth
Filter feeders, eat crustaceans,mollusks
More people are killed by lightning than sharks

19. Sharks and Rays

20. Bony Fish 15,000-40,000 species alive today
Ray-finned-(thin bony spines that are connected by a thin layer of skin to form fins.)
There are many adaptations of fins ( poison, leaping, climbing)
Only 7 are not classified as ray-finned fish

21. Lungfish
Some can use gills to eliminate CO2 and gulp air to receive O2
Coelacanth is a lobe-finned fish
Few bones in fin bases
Probably used these in ancient times to move from pool to pool
We thought they were extinct(found in 1938)
Closest living relative to land vertebrates

22. Coelacanth

23. How do fish fit into the world?
Important food source in many ecosystems
Control population growth (especially some plants)
Recreation in tanks

24. Amphibians Smallest groups of vertebrates
Fishlike aquatic organisms that breathe through gills, where as the adults are terrestrial and breathe through skin (there are exceptions)
Aquatic larvae
Eggs do not have a shell
Skin has not protection
If skin dries out they suffocate

25. Evolution ~360mya From lobe-finned fish
Bones became stronger for movement on land
Scales
Ears
Eyelids

26. Why were amphibians so successful?
The land was empty of life
Well established plant life
Arthropods were there (includes insects)
Plenty of food and space
Many became extinct after climate changes

27. Form and function of Amphibians
Feeding:
Larvae filter feed
Tadpoles are herbivorous
Adults are carnivorous
Food enters MouthEsophagusStomachSmall intestines(food absorbed)Large intestine (absorbs water) Cloaca (gets rid of waste)

28. Internal Anatomy of Frog

29. Permian Period

30. Respiration Lungs, Mouth, Skin
Skin is thin and and rich in blood vessels
They cannot exhale and inhale like we do.
Fill mouth with air and force it into lungs
Frogs croak by forcing air into a pair of vocal sacs in the back of the mouth

31. Internal Transport Linked to lungs in adults Double loop
1st loop carried O2 poor blood from heart to lungs and takes O2 rich blood from the heart to the rest of the body
2nd loop takes O2 rich blood from the heart to the rest of the body and and O2 poor blood from the body back to the heart

32. The heart Has 3 chambers: Left atrium, right atrium and ventricle
Blood from the body enters in the vena cava sinus venosus right atrium
Blood from the lungs enters the left atrium
Atria contractempty into ventriclebulbus cordusaortic arches to the rest of the body

33. Heart

34. Excretion Use kidneys to filter Nitrogenous waste from blood
Urine travels through tubes called ureters into the cloaca
Stored in bladder or expelled

35. Response Well developed nervous system
Eyes can move around and are protected by a transparent nictitating membrane
Can hear and sounds are used in calls for mating
Do not regulate body-temp
They can hide, run away, produce poison, or use camouflage to escape predators

36. Reproduction Male climbs on back of female
She releases eggs in the water
Male fertilizes these
Surrounded by a thick jelly as they develop
Tadpoles develop in 1-3 weeks
Not all amphibian eggs are fertilized externally

37. Frog Life Cycle

38. Salamanders Keep tails as adults Larvae and adult are carnivores
Some have gills for water
Some switch and live on land and return to the water to breed

39. Eastern Redback Salamander

40. Frogs and Toads Most live in water
Some toads have inhabited dry land (they can burrow in soil and absorb water like plants)
Many produce toxins

41. Poison frogs

42. How do Amphibians fit into the world?
Prey on insects
Tadpoles eat a lot of algae
Researchers are using poisons to see how the nervous system works
Salamander can regenerate and frogs cannot- under research