15. Phylum Chordata Notes

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

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

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

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

30. Pelvic fin Help the fish turn, balance, and brake

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

32. 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

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

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

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

36. 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

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

38. Lungfish Uses actual lungs to breathe and has reduced gills

39. 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

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

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

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

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