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Ichthyes: The Fish

Ichthyes: The Fish. What is a Fish? Aquatic vertebrate, usually with paired fins, scales and gills. -fins for movement -scales for protection -gills for respiration -Very diverse group composed of many classes of fish. -. Evolution of Fish -Fish were the first vertebrates

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Ichthyes: The Fish

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  1. Ichthyes: The Fish

  2. What is a Fish? • Aquatic vertebrate, usually with paired fins, scales and gills. • -fins for movement • -scales for protection • -gills for respiration • -Very diverse group composed of many classes of fish. • -

  3. Evolution of Fish -Fish were the first vertebrates -Two important developments : - jaws - paired fins The First Fish -Strange, jawless animals with bone armour. -Lived 500 million years ago and didn’t change for 100 million years

  4. The Age of Fish -400 million years ago -large adaptive radiation created new types of fish -the new fish species spread around the world -all were jawless -both soft-skinned and armoured fish appeared

  5. The Arrival Of Jaws and Paired Fins

  6. Jaws -allowed fish to eat new types of food -gave them protection Paired Fins -paired pectoral and pelvic fins -fins attached to girdles, bone structures in the body -fish could now swim quickly, hunt and protect themselves

  7. ModernFish Agnatha: jawless fish Chondrichthyes: cartilage fish Osteichthyes: Bony fish

  8. Feeding • every mode of feeding • Some will eat anything, others are very specialized • Food: • Enters mouth • Into esophagus • Stomach • Broken down further in the Pyloric Ceca • Intestine • Anus • Respiration • Most fish move water over their gills and take out the oxygen • Most fish have a single gill opening protected by the operculum • Lungfish have organs like lungs and can breathe air

  9. Circulation • Closed circulatory system (blood is in vessels) • A heart moves the blood in a loop around the body: heart-gills-body-heart • Complex, in most fish, the heart is a ________ chambered heart • Excretion • -Waste is removed in the form of ammonia • Kidneys help fish control the water in their • bodies • Response • -Well-developed brain with different parts • -Most fish have good sense organs • -Lateral Line System lets fish feel movement in • the water

  10. Movement: -muscles bend their bodies in a S-shaped movements -fish move forward -fins stabilize and steer -body is streamlined -many fish have a swim bladder to help them float

  11. Reproduction • -can be either internal or external fertilization • -fish that hatch from eggs are oviparous • Fish that are born alive are: • Ovoviviparous (embryos inside eggs) • Viviparous (embryos connected to the mother)

  12. Kingdom Animalia Phylum ChordataSubphylum Vertebrata • Class Agnatha [ag-nuh-thuh] – jawless fish ex: lamprey *minimal skeleton only a few cartilage plates • Class Chondrichthyes (con-drik-thee-eez] – cartilage fish ex: shark *entire skeleton is cartilage • Class Osteichthyes [os-tee-ik-thee-eez] – bony fish *most fish belong to this group and their skeleton is made largely of bone

  13. Class Agnatha • Jawless Fishes   • Jawless fishes have no true teeth or jaws. • Their skeletons are made of fibers and cartilage. • They lack vertebrae, and keep their notochords as adults. • Modern jawless fishes are divided into two classes: lampreys and hagfishes. Hagfish Lamprey

  14. Lampreys: • Lampreys are typically filter feeders as larvae and parasites as adults. • Adult lampreys attach themselves to fishes, whales, and dolphins. • They scrape away at the skin with small toothlike structures. • The lamprey sucks up the tissues and body fluids of its host.

  15. Hagfishes • Hagfishes have pinkish gray, wormlike bodies and four or six short tentacles around their mouths. • They lack eyes, but have light-detecting sensors scattered around their bodies. • They feed on dead and dying fish by using a toothed tongue to scrape a hole into the fish’s side.

  16. Class Chondrichthyes • The class Chondrichthyes contains sharks, rays, skates, sawfishes, and chimaeras. • The skeletons of these fishes are built entirely of cartilage. • Many sharks have thousands of teeth arranged in several rows. • Most species of sharks do not attack people. • Some skates and rays feed on bottom-dwelling invertebrates. • The largest rays eat floating plankton. • Skates and rays glide through the sea with their large, winglike pectoral fins. • Many skates and rays cover themselves with sand and rest on the ocean floor.

  17. Class Osteichthyes • Bony fishes make up the class Osteichthyes. • Their skeletons are made of bone. • Almost all living bony fishes are ray-finned fishes. • “Ray-finned” refers to the slender bony spines, or rays, that are connected by a thin layer of skin to form the fins. • Only seven living species of bony fishes are not classified as ray-finned fishes. • These are the lobe-finned fishes, a subclass that includes lungfishes and the coelacanth. • The fleshy fins of lobe-finned fishes have support bones. • Some of these bones are jointed.

  18. Some fishes spend most of their lives in the ocean but migrate to fresh water to breed. These fish are called anadromous. • Salmon are anadromous. • Catadramous fish are those that spawn in salt water and return to fresh water as they grow. • Atlantic eels are catadramous.

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