2. Classes of vertebrates include fishes, amphibians, reptiles, birds, and mammals.

3. Characteristics of Vertebrates
Chapter 28
Fishes and Amphibians
28.1 Fishes
Characteristics of Vertebrates
Notochord: flexible rod that is replaced by a backbone
Dorsal Nerve Cord: main nerve pathway to the brain
Pharyngeal slits: slits in the throat region (gills)

4. Chapter 28
Fishes and Amphibians
28.1 Fishes
Vertebral Column
Vertebral column made of cartilage or bone surrounds and protects the dorsal nerve cord.

5. The vertebral column functions as a strong, flexible rod that muscles can pull against during swimming or running.

6. Fish: Form and Function
Most fish have jaws, paired fins, gills, and scales

7. Chapter 28
Fishes and Amphibians
28.1 Fishes
Neural Crest
Neural crest: a group of cells that develop from the nerve cord in vertebrates.
Portions of the brain and skull, certain sense organs, and some nerve fibers are some of the structures that develop from the neural crest.

8. Anterior gill arches evolved into jaws in ancient fishes.
Chapter 28
Fishes and Amphibians
28.1 Fishes
Jaws
Anterior gill arches evolved into jaws in ancient fishes.

9. Fin: a paddle-shaped structure that is used for balance, steering,
Chapter 28
Fishes and Amphibians
28.1 Fishes
Paired Fins
Fin: a paddle-shaped structure
that is used for
balance, steering,
and propulsion
Paired fins reduce the
chance of rolling to the side and allow for better
steering during swimming.

10. There are four types of fish scales.
Chapter 28
Fishes and Amphibians
28.1 Fishes
Scales
There are four types of fish scales.
Ctenoid scales
Placoid scales
Cycloid scales
Ganoid scales

11. 28.1 Fishes Gills Respiration
Chapter 28
Fishes and Amphibians
28.1 Fishes
Gills Respiration
Fishes get oxygen when water that enters their mouths flows across their gills, where oxygen from the water diffuses into the blood.
Gills are composed of thin filaments that are covered with highly-folded, plate-like lamellae.

12. Operculum: bony structure that protects gills

13. Vertebrates have a closed circulatory system.
Chapter 28
Fishes and Amphibians
28.1 Fishes
Circulation
Vertebrates have a closed circulatory system.
In most fishes, the heart consists of two main chambers—the atrium and the ventricle.

14. Chapter 28
Fishes and Amphibians
28.1 Fishes
Feeding and Digestion
Most fishes swallow their food whole, passing it through a tube called the esophagus to the stomach, where digestion begins.

15. Kidneys: filter waste from blood
Chapter 28
Fishes and Amphibians
28.1 Fishes
Excretion
Kidneys: filter waste from blood
A nephron is a filtering unit within the kidney that helps maintain the salt and water balance of the body and to remove cellular waste products from the blood

16. Optic lobe: processes visual images
Chapter 28
Fishes and Amphibians
28.1 Fishes
The Brain and Senses
Olfactory bulb: smell
Optic lobe: processes visual images

17. Cerebellum: controls coordination
Medulla oblongata: regulates function of internal organs and helps maintain balance
Cerebrum: basic behaviors

18. Lateral line system: special sensor that allows fish to detect movements in water

19. The majority of fishes reproduce through external fertilization.
Chapter 28
Fishes and Amphibians
28.1 Fishes
Reproduction
The majority of fishes reproduce through external fertilization.
Spawning: release gametes near each other in the water

20. Swim bladder: filled with gas that assists with buoyancy
Chapter 28
Fishes and Amphibians
28.1 Fishes
Movement
Streamlined shape
Paired fins
Swim bladder: filled with gas that assists with buoyancy
Fishes move through the water by contracting muscle groups on either side of their bodies.

21. Chapter 28
Fishes and Amphibians
28.2 Diversity of Today’s Fishes
Classes of Fishes
Scientists have grouped fishes into three classes based on their body structure.
Jawless fishes
Cartilaginous fishes
Bony fishes

22. Lampreys are parasites that feed by attaching themselves to other
Chapter 28
Fishes and Amphibians
28.2 Diversity of Today’s Fishes
Jawless Fishes
Hagfish feed on soft-bodied invertebrates and dead or dying fish on the sea floor.
Lampreys are parasites that feed by attaching
themselves to other
fishes.
Lamprey

23. Have skeletons made of cartilage.
Chapter 28
Fishes and Amphibians
28.2 Diversity of Today’s Fishes
Cartilaginous Fishes
Have skeletons made of cartilage.
Usually top predators in the sea.
Sharks, skates and rays

24. Ray-finned: thin, spinelike rays support the fins
Chapter 28
Fishes and Amphibians
28.2 Diversity of Today’s Fishes
Bony Fishes
Two groups of bony fishes:
Ray-finned: thin, spinelike rays support the fins

25. Lobe-finned: have muscular lobes and joints similar to those of land vertebrates.

26. Characteristics of Amphibians
Chapter 28
Fishes and Amphibians
28.3 Amphibians
Characteristics of Amphibians
Most amphibians begin life as aquatic organisms.
Tadpole
After metamorphosis, they are equipped to live life on land.
Frog

27. Lay eggs in water
Have moist skin that lacks scales

28. As adults, their diets are similar as both groups become predators.
Chapter 28
Fishes and Amphibians
28.3 Amphibians
Feeding and Digestion
Most frog larvae are herbivores, whereas salamander larvae are carnivores.
As adults, their diets are similar as both groups become predators.
The digestive system of an amphibian is very similar to that of a fish.

29. Diffusion through skin
Chapter 28
Fishes and Amphibians
28.3 Amphibians
Excretion
Kidneys (most)
Diffusion through skin
Ammonia is excreted by amphibians that live in the water.
Urea is stored in the bladder and removed from the body through the cloaca.

30. Cloaca: posterior opening at the end of the digestive tract used to excrete urine and feces.

31. Chapter 28
Fishes and Amphibians
28.3 Amphibians
Respiration
As larvae, most exchange gases through their skin and gills (diffusion)
As adults, most breathe through lungs, their thin, moist skin, and cavities in the mouth.

32. Amphibians have a double-loop circulatory system.
Chapter 28
Fishes and Amphibians
28.3 Amphibians
Circulation
Amphibians have a double-loop circulatory system.
Amphibians have three-chambered hearts.

33. Frogs have nictitating membranes that protect their eyes.
Chapter 28
Fishes and Amphibians
28.3 Amphibians
The Brain and Senses
Amphibians use sight
Frogs have nictitating membranes that protect their eyes.
Tympanic membrane to hear high-pitched sounds and to amplify sounds from the vocal cords.

34. Reproduction and Development
Chapter 28
Fishes and Amphibians
28.3 Amphibians
Reproduction and Development
In most amphibians, fertilization is external
Eggs must be laid and fertilized in water
Tadpoles hatch from the egg and undergo metamorphosis from a fishlike animal to an air-breathing one.
Virtual Frog Dissection

36. Anura includes frogs and toads
Chapter 28
Fishes and Amphibians
28.3 Amphibians
Amphibian Diversity
Three orders:
Anura includes frogs and toads

37. Caudata includes salamanders and newts

38. Gymnophiona includes caecilians