Phylum Chordata

1. Phylum Chordata

2. Phylum Chordata- Chordates • Chordates have these features at some point during their life • Notochord - A firm, flexible rod of specialized cells that becomes the endoskeleton in vertebrates • Dorsal nerve cord - A hollow tube above the notochord that becomes the spinal chord and brain in vertebrates • Pharyngeal pouches • Become gill chambers and gills in aquatic chordates. • Become jaws, inner ear, and tonsils in terrestrial chordates. - Post-anal tail • A tail located posterior to the anal opening.

3. Phylum Chordata • More Features • Bilateral symmetry • Complete digestive system • 3 germ layers (endoderm, mesoderm, ectoderm) with a well developed coelem • Bony or cartilaginous skeleton usually present

4. Classification of Chordata • Subphylum urochordata- tunicates • Class Amphibia-amphibians • Class Aves-birds • Class Chondricthyes- cartilaginous fishes • Class Osteichthyes- bony fishes • Class Mammalia-mammals • Class Reptilia-reptiles

5. Subphylum Vertebrata • Dominate upper levels of the food chain in almost all food webs • Dorsal nerve cord develops into a spinal cord protected by vertebrate • Has a head and developed brain with a skull

6. ICHTHYOLOGY • The scientific study of fishes • Fishes appeared 500 mya • First fishes- Probably evolved from tadpole larvae

7. Body shape Coloration Locomotion Feeding Digestion Circulatory system Respiratory system Homeostasis Nervous system Behavior Reproduction WHAT CHARACTERISTICS ARE WE LOOKING AT?

8. BODY SHAPE • Directly related to lifestyle • Fast swimmers are streamlined (like a torpedo) • Ex: sharks, tunas, mackerels, marlins • Leisurely swimmers are laterally compressed • Good enough for quick bursts to escape predators or capture prey • Ex: snappers, damselfishes

9. BODY SHAPE (continued) • Directly related to lifestyle (continued) • Pelagic fishes can be flattened: • Laterally • Ex: Flounder, sole, halibut • Ventral-dorsal • Ex: rays, skates • Elongated, snake-like shape • Ex: moray eels, trumpetfishes

10. COLORATION • Pigments in chromatophores • Some species change depending on season, time of day, location • Structural colors • like tiny mirrors • Indicates • mood • reproductive condition • warning colors • camouflage

11. COLORATION (continued) • Types of camouflage • Cryptic coloration • Blending with the environment • Disruptive coloration • Difficult for predators to focus on individual • Color stripes, bars, or spots • Countershading • Light ventral, dark dorsal

12. LOCOMOTION • Obtain food • Escape predators • Find mates • Flush gills with oxygenated water

13. LOCOMOTION(continued) • Most use a rhythmic side-to-side motion • Use muscles called myomeres • Compare the locomotion of bony fish and sharks

14. Sharks do NOT have swim bladder So they have large pectoral fins for lift Large upper lobe of caudal fin Large amount of oil in liver Bony fish have a swim bladder Pectoral fins used for maneuverability Allows them to hover Dorsal and anal fins steer and provide stability Pelvic fins help in turning, balance, and stopping LOCOMOTION(continued)

15. Types of Fishes • 24,000 species known • More are discovered all the time • Three major groups • Jawless fishes • Bony fishes • Cartilaginous fishes

16. Class Agnatha- Jawless fishes • Most primitive • Simplest of all fishes • Lack jaws, feed by suction • Lampreys and hagfishes • Hagfishes • Scavengers feed off of dead or dying fishes • Sometimes they eat prey inside out

17. Chondricthyes • Sharks and Rays • About 1,000 species of sharks, skates, rays • All jawed fish • Lack a swim bladder • Have cartilaginous skeletons • Range in size from small enough to fit in your hand to largest fish in the ocean • Whale sharks- up to 14 meters (46 feet)

18. Chondricthyes • Energy efficient –need way less energy to live than other organisms the same size • How do they save energy? • Ambush hunters- most people who have survived a shark attack say that they were not even aware of the shark until it struck • cartilage is much lighter than bone • They use less energy trying to stay buoyant in water

19. Chondricthyes • Carry buoyant oils in large livers to help aid in buoyancy • Sharks fins are angled to provide life • Asymmetrical tails help to produce lift as well • Denticles- scales that point backwards • Help to trap water close to the sharks body which helps reduce friction during swimming

20. Chondricthyes • Maintaining homeostasis • Fish need to keep water from diffusing out of their bodies • Bony fish pump water out • Chondricthyes store chemicals in their tissues so the water density inside matches the density outside • This process saves tremendous energy

21. Chondricthyes • Teeth growth and replacement • Bony fish have teeth fused to bone in mouth • when they lose a tooth it takes time for a new one to grow • Sharks have a “conveyer belt” of multiple rows of teeth- replacement is immediate • Some species produce 25,000 in a lifetime

22. Chondricthyes • Sharks have an incredible sense of smell. Lab tests show that sharks can smell fish extracts as dilute as one part per 10 billion parts water • Lateral lines- sharks, rays, and bony fish have these. Sensory pores that run the length of the body. Allows fish to detect vibrations in the water

23. Chondricthyes • Ampullae of Lorenzini • Electric sense system • Tiny gel filled canals positioned in the head region • Used for sensing prey and navigation

24. Chondricthyes • Reproduction- these organisms reproduce fewer more mature offspring than other fish • Sharks fertilize eggs internally/bony fishes externally • Juveniles develop within a protected egg sac until mature (about 9 months) • Oviviparous- some sharks give birth to live young.

25. Class Osteichthyes- Bony fishes • 23,000 species • 96% of fishes and almost half of vertebrates • Usually have flexible overlapping scales which are made of bone • Scales covered by a thin layer of skin and protective mucus • Have fins which are flexible • Used for propulsion and maneuverability

26. Class Osteichthyes- Bony fishes • Jaws have freedom to move, teeth are attached to jawbones • Have a swim bladder • Gas-filled sac above the stomach and intestine • Allows fish to adjust buoyancy to keep from sinking and floating • Many bony fish have an organ called the gas gland which supplies gases from bloodstream to the swim bladder

27. Class Osteichthyes- Bony fishes • Most reproduce externally. Females lay eggs in mass numbers, some in millions • Male immediately fertilizes • Some species defend eggs • Most have lateral lines to sense vibrations • Torpedo shaped body minimizes drag and turbulence • Counter shading

28. Unique Fish Adaptations

29. Electric Eels • Not a true eel • Have electric organs specialized cells called electrocytes • can release 600 volts at a time- 5X an electric socket

30. Pufferfish • Are slow swimmers • To evade predators their expandable stomachs with water, making it difficult to eat them • Foul tasting and toxic to eat • Tetrodotoxin is deadly, toxin in one fish can kill 30 humans • No antidote • Fugu eaten in Japan

31. Stonefish • Worlds most venomous fish • venom causes such a severe pain that the victims of its sting want the affected limb to be amputated. • Fatal within a couple of hours • Stonefish stores its toxins in gruesome-looking spines that are designed to hurt would-be predators. • Live in South Pacific and Indian Oceans

32. Camouflage • Some fish can change their color to match their environment