Phylum Chordata & Types of Fish

1. Phylum Chordata & Types of Fish Kingdom Animalia Phylum Chordata Subphylum Urochordata Subphylum Cephalochordata Subphylum Vertebrata Class Agnatha Class Chondrichthyes Class Osteichthyes

2. Phylum Chordata • “Chordates” • Contains invertebrate and vertebrate species • All have bilateral symmetry • All at one point have a notochord, dorsal nerve cord, pharynx, and gill slits

3. Notochord • A long rod of stiffened tissue • Not bone or cartilage

4. Nerve Cord • Tube found on the dorsal side that runs parallel to the notochord and gut • Anterior end enlarges during development to form brain

5. Pharynx • A muscular tube that acts in feeding, respiration, or both

6. Gill Slits • A means of removing oxygen from a liquid environment for respiration

7. Subphylum Urochodata • Includes: Tunicates or Sea Squirts • Similar niche to sponges but far more complex animal • Filter feeder, diatoms and other bits of food caught in gill slits • Leathery “tunic” secreted and covers the body

8. Subphylum Cephalochordata • Includes: Lancelets (called due to shape) • Shows the four distinct characteristics of chordates • Closed circulatory system • Respiratory gases diffuse across the body • Filter feeders

9. Subphylum Vertebrata • 7 Current Classes: • Agnatha – jawless fish • Chondrichthyes – Cartilaginous fish • Osteichthyes – Bony fish • Amphibia – Amphibians • Reptilia – Reptiles • Aves – Birds • Mammalia - Mammals

10. Characteristics of Vertebrates: • Many chordata characteristics seen in embryo stage • Nerve cord develops into a spinal cord and a brain

11. Two Large Advances: • Spinal cord is protected by a bony vertebrae • Brain is protected by a bony skull

12. Other Evolutionary Advancements • Expansion of species began with the evolution of a jaw developed from the structure supporting the gill slits • This lead to the ability to hunt other animals and thus led to advances in the nervous system and other body system processes

13. Other Evolutionary Advancements • Development of fleshy and skeleton fins that became the starting point for arms, legs, and wings • Evolution of gills allowed for better diffusion of oxygen • Gills developed into pouches then developed into lungs

14. Ichthyology • The study of fishes

15. Class Agnatha • “Jawless Fishes” • Most primitive fish • Lacks jaws and feed by suction • Cylindrical and elongated body • Lack paired fins and scales

16. Hagfish & Lampreys • Hagfish • Feed mostly on dead or dying fish • Lampreys • Mostly freshwater • Attach to other fish and suck their blood

17. Class Chondrichthyes • “Cartilaginous Fish” • Skeleton made of cartilage • Movable jaws with well-developed teeth • Rough sand paper like scales made of the same composition of the teeth

18. Sharks & Ratfish • Sharks • Adapted for fast swimming and to be predators • Ratfish or Chimeras • Bottom dwellers • Have long “rat-like” tails

19. Rays and Skates • Rays • Flattened bodies with gills on the bottom of their bodies • Whip-like tail with stinging spines (venomous) • Skates • Very similar to rays but with out the long tail or stinging spines

20. Class Osteichthyes • “Bony Fish” • Make of 98% of all fish and over half the vertebrates • Skeleton at least made partially of bone • Thin, flexible, overlapping scales • Mouth located at end of body • Presence of gas-filled sac called a swim bladder

21. Body Shape • Body shape is varied and linked to its lifestyle • Fast swimmer need elongated bodies

22. Body Shape • Short, compressed bodies good for navigating tight places like reefs • Bottom dwellers tend to have flattened shapes

23. Body Shape • Elongated shapes are need for life in narrow spaces • Some have less generalized shapes

24. Body Shape • Some shapes are conducive to camouflage with their environment

25. Exterior Layer

26. Locomotion • Fish swim with rhythmic side to side motion of the body or tail • Rhythmic contractions produced by bands of muscle called myomeres

28. Locomotion • Swim bladder – specialized organ filled with gas that assists in floating due to a heavier bone structure (found in bony fish)

29. Pectoral Fins • Oversized in sharks to provide lift due to no swim bladder, provide tight maneuverability in bony fish

30. Dorsal & Anal Fins • Employed as rudders used to steer and provide stability

31. Pelvic fin • Help the fish turn, balance, and brake

32. Caudal (tail) fin • Used in steering and force production

34. Lobe-Finned Fish • Link between water based fish and land dwelling amphibians • Developed bone/cartilage appendages that allowed them to move in mud and shallow waters • Developed primitive lungs as well

35. Digestion • Food passed through esophagus into the stomach for digestion and on into an intestine

36. Digestion • Pancreas, liver, and the pyloric caeca secrete digestive enzymes

38. Respiratory System • Fish get oxygen that is dissolved in the water • They must get water to flow over gills to do this, called irrigation

40. Gill Structure • The gill is supported by cartilaginous or bony structure called gill arch • Gill rakers are used as filters to stop food from entering gills • Gill filaments contain the capillaries

41. Circulatory System • Closed circulatory system • Two chambered heart • Gas exchange happens in the gills

42. Lungfish • Uses actual lungs to breathe and has reduced gills

43. Regulating Internal Environment • The blood of marine fish is less salty than the water, therefore they lose water through osmosis • To replace it they must drink seawater

44. Nervous System • Central nervous system consisting of brain • Highly developed sense of smell due to olfactory bulb/sacs which open to the nostrils

45. Nervous System • Some bottom feeders like catfish have whisker like organs called barbels

46. Lateral Line • Unique sense organ that enables them to detect vibrations in the water • Canals inside the body connected to surface by pores

47. Ampullae of Lorenzini • Can detect very weak electrical fields • Used to locate prey and navigate