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2. Resources Chapter Presentation Visual Concepts Transparencies Standardized Test Prep

3. Chapter 39 Fishes Table of Contents Section 1 Introduction to Vertebrates Section 2 Jawless and Cartilaginous Fishes Section 3 Bony Fishes

4. Section 1 Introduction to Vertebrates Chapter 39 Objectives • Identifythe distinguishing characteristics of vertebrates. • Listan example for each of the nine classes of vertebrates. • Describethe characteristics of the early vertebrates. • Explainthe importance of jaws and paired fins for fishes.

5. Section 1 Introduction to Vertebrates Chapter 39 Characteristics Vertebrates are members of the subphylum Vertebrata, within the phylum Chordata. All Chordates share the following characteristics. • Notochord • Dorsal hollow nerve cord • Pharyngeal gill slits • Post-anal tail

6. Section 1 Introduction to Vertebrates Chapter 39 Characteristics, continued Vertebrates are distinguished from chordates by: • Vertebrae - bones or cartilage that surround the dorsal nerve cord and form the spine. • A cranium - a skull that protects the brain • An endoskeleton - an internal skeleton made of bone or cartilage

7. Section 1 Introduction to Vertebrates Chapter 39 Characteristics, continued Vertebrates are divided into nine classes: • Myxini - hagfishes • Cephalaspidomorphi - lampreys • Chondrichthyes - sharks, rays, skates, and ratfishes • Actinopterygii - ray-finned fishes • Sarcopterygii - lobe-finned fishes • Amphibia - frogs, toads, salamanders, and caecilians • Reptilia - lizards, snakes, and turtles • Aves - birds • Mammalia - mammals

8. Section 1 Introduction to Vertebrates Chapter 39 Evolutionary Relationships Among Chordates

9. Section 1 Introduction to Vertebrates Chapter 39 Vertebrate Evolution • Most biologists think that vertebrates originated about 560 million years ago. • The first fish were jawless. • About 450 million years ago, the first fishes with jaws and paired fins appeared. • Jaws are thought to have evolved from the first pair of gill arches, the skeletal elements that support the pharynx.

10. Section 1 Introduction to Vertebrates Chapter 39 Evolution of Jaws

11. Section 1 Introduction to Vertebrates Chapter 39 Vertebrate Evolution, continued The advantages to jaws and paired fins: • Paired fins increased fishes’ stability and maneuverability in water • Jaws allowed fishes to seize and manipulate prey

12. Section 1 Introduction to Vertebrates Chapter 39 Origin of Jaws

13. Section 1 Introduction to Vertebrates Chapter 39 Advantage of Paired Fins

14. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Objectives • Identify three characteristics that make fishes well suited to aquatic life. • Describethree sensory systems in fish. • Evaluatethe similarities between jawless fishes and early vertebrates. • Identifytwo characteristics of cartilaginous fishes. • Contrastreproduction in lampreys with reproduction in cartilaginous fishes.

15. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Fish Adaptations Fish have several adaptations that make them well suited to life in water: • Streamlined body plan - allows fish to move rapidly in water • Adaptations for buoyancy - stored gases or lipids help maintain vertical position in water • Efficient respiration - internal gills exchange gases efficiently

16. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Fish Adaptations, continued Adaptations for salt and water homeostasis - • The concentration of solutes in a fish’s body usually differs from the concentration of solutes in the water. • Fish have adaptations to maintain ion and water homeostasis.

17. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Fish Adaptations, continued Sensory adaptations - Fish have a variety of organs that allow them to sense their environment. • Sight: fish eyes are similar to eyes of land vertebrates • Sound: fish have internal ears sensitive to sound • Chemoreception: the ability to detect chemicals in the environment includes the senses of smell and taste. Fish have nostrils and tastebuds. Tastebuds may be located in their mouths, on their lips, fins, and skin, and on whisker-like organs called barbels.

18. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Fish Adaptations, continued Unique senses: • Lateral line: the lateral line is a system of canals in the skin that allow fish to sense vibration in the water • Ampulae of Lorenzini: cartilaginous fishes have sense organs called ampulae of Lorenzini that can detect weak electrical fields • Electroreception and Magnetoreception: some fish have the ability to detect electrical and magnetic fields

19. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Lateral Line in Fishes

20. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Lateral Line System

21. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Characteristics of Fish

22. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Jawless Fishes Only two classes of jawless fishes are alive today: • Hagfishes (class Myxini) Hagfishes are bottom-dwellers that feed on dead and dying fish. • Lampreys (class Cephalaspidomorphi) Lampreys can be free-living or parasitic. Parasitic lampreys attach themselves to their host with disc-shaped mouths and feed on the blood and body fluids of other fishes. All lampreys breed in fresh water. Fertilization occurs outside the body - external fertilization.

23. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Cartilaginous Fishes All cartilaginous fishes: • belong to the class Chondrichthyes. • have skeletons made of cartilage - a flexible lightweight material made of cells surrounded by tough fibers of protein. • have skin covered with placoid scales - small, toothlike spines that feel like sandpaper. Placoid scales probably reduce turbulence and increase swimming efficiency.

24. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Cartilaginous Fishes, continued Sharks: • Sharks have torpedo shaped bodies that reduce turbulence when swimming, called a fusiform body shape. • Some sharks are filter feeders, and have slender projections on the inner surface of their gills, called gill rakers, that filter the water. • The mouth of a typical shark has 6 to 20 rows of teeth. When a tooth breaks or wears down, a replacement moves forward. One shark may use more than 20,000 teeth over its lifetime.

25. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Cartilaginous Fishes, continued

26. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Cartilaginous Fishes, continued Rays and Skates: • Rays and skates have flattened bodies with paired wing-like pectoral fins and, in some species, whip-like tails. • Rays have diamond- or disk-shaped bodies. Most skates have triangular bodies. • Rays and skates are primarily bottom dwellers, and most feed on mollusks and crustaceans.

27. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Cartilaginous Fishes, continued Ratfishes: • Ratfishes are a small group of strange looking fish that have a flap of skin covering their gill slits. • Ratfishes have long, rat-like tails and feed on crustaceans and mollusks.

28. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Cartilaginous Fishes, continued Adaptations in Cartilaginous Fishes: • Some sharks push water through their mouth and over their gills by swimming. • Most cartilaginous fish pump water over their gills by expanding and contracting their mouth cavity and pharynx. • When lying on the bottom, rays and skates draw water in to their gills through spiracles, two large openings on the top of the head, behind the eyes.

29. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Cartilaginous Fishes, continued Adaptations in Cartilaginous Fishes: • Sharks convert ammonia to urea in their bodies. • Sharks retain large amounts of urea in their bodies to raise the concentration of solutes in their bodies to the same level as that found in sea water. • Sharks still tend to take up sodium and chloride ions. • The rectal gland removes excess sodium and chloride ions from the body.

30. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Cartilaginous Fishes, continued Adaptations in Cartilaginous Fishes: Cartilaginous fishes maintain their position in the water in two ways. • The caudal and pectoral fins generate lift, or upward force, as the fish swims. • Many cartilaginous fish store large amounts of lipids, usually in the liver. Lipids are less dense than water.

31. Section 2 Jawless and Cartilaginous Fishes Chapter 39 Cartilaginous Fishes, continued Reproduction in Cartilaginous Fishes: • Fertilization occurs inside the body of the female, called internal fertilization. • Some cartilaginous fish lay eggs. • The eggs of many species develop within the female’s body. • In some species, the mother nourishes the developing young while they are in her body.

32. Section 3 Bony Fishes Chapter 39 Objectives • Listthree characteristics of bony fishes. • Distinguishbetween lobe- finned fishes and ray-finned fishes. • Describethree key features of bony fishes’ external anatomy. • Summarizethe major body systems in bony fishes. • Describethe function of the swim bladder. • Discussreproduction in bony fishes.

33. Section 3 Bony Fishes Chapter 39 Characteristics of Bony Fishes Bony fishes have three key features: • Bone - the skeletons of most bony fishes contain bone. • Lungs or swim bladder - early bony fishes had lungs, organs which exchange gas between the air and blood. Most bony fishes today have a swim bladder, a gas-filed sac that is used to control buoyancy. • Scales - scales protect the body of a bony fish and reduce friction when swimming.

34. Section 3 Bony Fishes Chapter 39 Swim Bladder in Bony Fish

35. Section 3 Bony Fishes Chapter 39 Swim Bladder

36. Section 3 Bony Fishes Chapter 39 Characteristics, continued There are two main groups of bony fishes: • Lobe-finned fishes - have fleshy fins supported by a series of bone. • Ray-finned fishes - have fins that are supported by long, segmented, flexible bony elements called rays.

37. Section 3 Bony Fishes Chapter 39 Characteristics of Bony Fishes

38. Section 3 Bony Fishes Chapter 39 Ray-Finned Fishes

39. Section 3 Bony Fishes Chapter 39 External Anatomy • Operculum Most bony fish have an operculum, a hard plate that opens at the rear and covers and protects the gills. • Fins The fins of most fish are supported by rays or spines. Rays are flexible, spines are rigid. • Skin The skin of most bony fish are covered with scales. Scales are thin, round disks of a bonelike material that grow from pockets in the skin and overlap like shingles.

40. Section 3 Bony Fishes Chapter 39 External Structures of Fish—Yellow Perch

41. Section 3 Bony Fishes Chapter 39 Anatomy of a Bony Fish

42. Section 3 Bony Fishes Chapter 39 Internal Anatomy • Skeleton The major parts of a fish’s skeleton are the skull, spinal column, pectoral girdle, pelvic girdle, and ribs.

43. Section 3 Bony Fishes Chapter 39 Internal Anatomy, continued Digestive system Food passes from the mouth into the pharynx, through the esophagus, to the stomach. From the stomach food passes into the intestine, where nutrients are absorbed. Undigested material is eliminated through the anus.

44. Section 3 Bony Fishes Chapter 39 Internal Structure of Fishes—Yellow Perch

45. Section 3 Bony Fishes Chapter 39 Internal Anatomy, continued Circulatory system The circulatory system of a fish delivers oxygen and nutrients to the cells of the body. The circulatory system consists of a heart, blood vessels, and blood. The heart pumps blood through arteries to small, thin-walled vessels called capillaries, in the gills. From the gills, the blood travels to the body tissues, where nutrients and wastes are exchanged. The blood returns to the heart through veins.

46. Section 3 Bony Fishes Chapter 39 Internal Anatomy, continued Circulatory system The heart of a bony fish has two chambers in a row, as shown below. Blood from the body enters the sinus venosus, moves into the atrium, then into the ventricle. From the ventricle it enters the conus arteriosus, and then goes to the gills.

47. Section 3 Bony Fishes Chapter 39 Fish Heart Structure

48. Section 3 Bony Fishes Chapter 39 Fish Heart and Single-Loop Circulation

49. Section 3 Bony Fishes Chapter 39 Internal Anatomy, continued Respiratory system • Fish use gills for gas exchange. • Water flows across the gill filaments in a direction opposite to blood flow, called countercurrent flow. • Countercurrent flow allows more oxygen to diffuse into the blood than would be possible if blood and water flowed in the same direction.

50. Section 3 Bony Fishes Chapter 39 Respiration in Fishes