Chapter 30

1. Chapter 30 Chordates, Fishes, and Amphibians

2. Chapter 30 - Vocabulary • Tetrapod – 4 limbs • Chordate • Notochord • Pharyngeal Pouch • Vertebra • Swim Bladder • Cartilage • Oviparous • Ovoviviparous • Viviparous • Cloaca • Tympanic Membrane • Gills

3. The Chordates 30-1

5. What Is A Chordate? • Phylum: Chordata • There are 4 key characteristics that must be present at some stage in a chordates life cycle: • Dorsal, hollow nerve cord • Notochord • Pharyngeal Pouches • A tail that extends beyond the anus

6. Nonvertebrate chordates (4%) Mammals (8%) Birds (18%) Fishes (47%) Reptiles (14%) Amphibians (9%)

7. What is a Notochord? • Flexible, rod-like structure • First part of the endoskeleton to appear in an embryo • Place where muscles attach • In vertebrates, the notochord is replaced by the vertebrae. • Remains persist between each vertebrae.

8. Dorsal Nerve Cord • Tube-like structure • Anterior end becomes enlarged to form the brain • Protected by the vertebral column in vertebrates

9. Pharyngeal Pouches and Slits • Pharyngeal Slits: • openings that lead from the pharyngeal cavity to the outside. • modified for gas exchange in aquatic vertebrates. • develop into parts of the ear, head, and neck in terrestrial vertebrates. • In tetrapods, the pharyngeal pouches give rise to the Eustachian tube, middle ear cavity, tonsils, and parathyroid glands.

11. Post-Anal Tail • In aquatic vertebrates, evolved for propulsion in water. • In humans, reduced to coccyx (tail bone).

12. Chordates – 2 Subphyla • Cephalochordata • Invertebrates (no backbone) • 2 Groups make up about 4% • Tunicates (Sea Squirt) • Lancelets • Vertebrata • Have a backbone • 5 Groups make up about 96% • Fishes • Amphibians • Reptiles • Birds • Mammals

13. Vertebrates • Dorsal hollow nerve cord is called the spinal cord, the front end develops into the brain. • The backbone replaces the notochord and is made of vertebrae. • Part of endoskeleton • Supports and protects • Muscles attach here • Grows as the animal grows • Made of living cells

14. Why are the 5 groups of vertebrates called vertebrates? Fishes Reptiles Amphibians Birds Mammals

15. Fish 30-2

16. What is a Fish? • Aquatic Vertebrates • Most fish have the following: • Paired Fins (movement) • Scales (protection) • Gills (gas exchange) • They are a varied group of animals. • Make up about half of all known species of vertebrates.

17. Evolution • Fish were the first vertebrates to evolve. • Modern sharks and rays evolved a skeleton made of strong, resilient cartilage. • Other groups evolved skeletons made of true bone. • 2 Major Adaptations: • Jaws • Used to hold teeth and muscle • Defense mechanism • Paired Fins • Made of cartilage (flexible) • Allowed for more swift body movement

18. Form & Function • Feeding – herbivores, carnivores, parasites, filter feeders, detrivores. • Respiration – breathe through gills made up of filaments. • Circulation – closed with a well defined heart. • Excretion – kidneys control the amount of water. • Response – well-developed brain with several parts (cerebrum, cerebellum, medulla oblongata, lateral line). • Movement – muscle contraction and swim bladder (gas-filled organ that adjusts buoyancy).

19. Reproduction • Eggs are fertilized either internally or externally depending on the species. • Oviparous – eggs hatch outside the mother’s body • Ovoviviparaous – eggs stay in the mother’s body after internal fertilization, use yolk for nourishment, born alive • Viviparaous – eggs stay in the mother’s body after internal fertilization, obtain nutrients from the mother’s body, born alive

20. Anatomy of a Fish • Pyloric ceca– fingerlike pouches in which food is processed and nutrients absorbed • Esophagus – short tube that connects mouth to stomach • Intestine – completes process of digestion and nutrient absorption • Pancreas – adds digestive enzymes to food as it moves through gut • Anus –opening through which undigested material is expelled *You will use this information for the shark dissection*

21. Anatomy of a Fish • Stomach - where food is partially broken down • Operculum – protective bony cover over the gill • Swim bladder– inflates and deflates to give buoyancy to fish • Lateral line system– receptors that allow fish to detect currents in water • Kidneys– filters metabolic byproducts of cellular respiration *You will use this information for the shark dissection*

22. Pyloriccecum Esophagus Stomach Kidney Brain Swimbladder Vertebra Gills Spinalcord Muscle Mouth Operculum Heart Anus Urinarybladder Reproductiveorgan Pancreas Gallbladder Intestine Liver Internal Anatomy (Figure 30-11) *You will use this information for the shark dissection*

23. Groups of Fishes • Major Groups: • A) Cartilaginous– Chondrichthyes, includes sharks, rays, skates, sawfish, and chimaeras • B) Bony– Osteichythes • Ray Finned – most fish • Lobe Finned – Lungfishes and Coelacanth • C) Jawless– no vertebrate, includes lampreys and hagfishes

24. Cartilaginous Fish • Class: Chondrichthyes • Sharks, Rays, Skates, Sawfish, Chimaeras

25. Sharks • Jaws have 20 tons per square inch for an 8’ shark • Most have curved tails, torpedo-shaped bodies and thousands of teeth arranged in rows that are constantly replaced • Size varies (few inches to over 40 feet) • Variable body shapes and mouth structure

27. Skates and Rays • Wing-like pectorals • Most live on sea beds • Some have poison spines on backs or tails (stingrays)

28. Bony Fish • Class: Osteichthyes • Ray-Finned • Lobe-Finned

29. Bony Fish • Largest group of fishes includes ray-finned fishes such flounder, angelfish, lobe-finned fishes such as lungfish • Skeleton made of bone • Hinged jaws • Paired fins • Hard, protective scales • Covered gills (operculum)

30. External Anatomy

31. Jawless Fish • Lampreys • Filter feeders as larvae • Parasites as adults • Sucks tissue and body fluids from host • Hagfish • Lack eyes • Feed on dead and dying fish

32. Ecology • Fish have adaptations that allow them to live in either fresh or saltwater. • Some fish like salmon can move from saltwater ecosystems to freshwater and vise versa. • These fish are called anadromousfish. • Fish that begin in fresh water but migrate to salt water are called catadromous fish. • Examples are European eels.

33. Amphibians 30.3

34. What is an Amphibian? • Word Amphibian means “Double Life” • Vertebrates • Tetrapods • Class: Amphibia • Live in water and on land • Generally in water as larva and on land as adults

35. Evolution • Challenges of transitioning from water to land: • Needed legs to climb out of water • Needed some way to breathe air • Needed protection from drying out • Adaptations: • Bones in the limbs • Lungs and breathing tubes

36. Form & Function • Feeding – adults are almost entirely carnivorous • Respiration – lungs replace gills when become adult • Circulation – well-developed heart with 3 chambers • Excretion – kidneys filter waste out of the blood • Movement – legs for walking, running, jumping • Response – well-developed nervous system

37. Reproduction • Lay eggs in water • Males call to attract females • External Fertilization

38. Groups of Amphibians • Salamanders & Newts • Order: Urodela • 4 legs • Live in moist woods • Frogs & Toads • Order: Anura • 4 legs adapted for jumping • Closely tied to water • Caecillians • Order: Apoda • Legless animals • Live in water or burrow into soil

39. Ecology • Amphibians are going extinct at a faster rate than any other group, mainly in the tropics. • Reasons • habitat loss, climate change, UV-B radiation, pollution, disease, overharvesting • Bioindicators • amphibians show how healthy or polluted a habitat is