1 / 19

Chordates

Chordates. Biology 112. Characteristics of Phylum Chordata. A chordate is an animal with the following four features: A hollow nerve cord that runs along the back of the body A notochord is a support rod that runs just below the nerve cord

min
Download Presentation

Chordates

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chordates Biology 112

  2. Characteristics of Phylum Chordata • A chordate is an animal with the following four features: • A hollow nerve cord that runs along the back of the body • A notochord is a support rod that runs just below the nerve cord • Pharyngeal pouches are paired structures in the throat • A tail that extends beyond the anus

  3. Characteristics of Chordates

  4. Generally speaking… • Most chordates are vertebrates • Most have a backbone made up of vertebrae • The backbone replaces the notochord and supports and protects the spinal cord • It also gives muscles a place to attach

  5. Chordates that do not have backbones • Tunicates • Ocean-living filter feeders • Have no notochord or tail • As larva, they possess all the characteristics of chordates • Lancelets • Small, fish-like animals • Adults possess all four characteristics • Have a definite head region

  6. Tunicates – comparison of larva to adult

  7. Lancelet - adult

  8. Fishes • Aquatic vertebrates • Most have paired fins, scales and gills • Jaws and paired fins marked an evolutionary turning point for fish • Jaws improved defense and expanded food choices • Paired fins improved controlled movement • In order to survive in water, special adaptations include: • Various modes of feeding • Specialized structures for gas exchange • Paired fins for locomotion

  9. Fish - feeding • May be herbivores, carnivores, parasites, filter feeders, or detritus feeders • One fish may feed in many different ways, depending on the food available

  10. Fish - respiration • Most fish breathe with gills • Gills have many tiny blood vessels that provide a large surface area for gas exchange • Fish pull water into their mouths • Water moves over the gills and out of the body through openings in the sides of the pharnyx

  11. Fish - circulation • Fish have a closed circulation system • It pumps blood in a loop from its heart to gills to the body and then back to the heart • The heart consists of two chambers: an atrium and a ventricle

  12. Fish - excretion • Most fish get rid of wastes as ammonia • Some diffuse wastes through the gills into the water • Others remove wastes from the blood through the kidneys • Kidneys help control the amount of water in their bodies

  13. Fish – nervous system • Well developed with a brain housing several parts • Cerebrum responsible for smell • Cerebellum coordinates movement • Medullaoblongata controls internal organs • A lateral line system senses currents and vibrations in the water

  14. Fish - movement • Most move by contracting muscles on either side of the backbone • Fins pull the fish forward and help it steer • Many have a gas-filled organ called a swim bladder that prevents its from sinking

  15. Fish - reproduction • Eggs may be fertilized internally or externally • Oviparous fish • Lay eggs • Eggs develop and hatch outside the mother’s body • Ovoviviparous fish • Develop eggs inside the mother • Egg provides food to the young while inside mother • Young are born alive • Viviparous fish • Mother provides food to the young while inside mother • Young are born alive

  16. Classification of Fish • Jawless fish • Lampreys and hagfish • Bodies are supported by a notochord • Do not have true teeth or jaws • Parasites and scavengers • Cartilaginous fish • Sharks, rays and skates • Have a skeleton made of cartilage • Most have tooth-like scales covering their bodies • Bony fish • Skeletons made of bone • Most are ray-finned fishes • Fins have thin, bony spines that are joined by a thin layer of skin

  17. Amphibians • Vertebrates that live mostly in aquatic environments as a larva and on land as an adult • As adults, breath with lungs, have moist skin that contains mucous glands and lack scales and claws • In order for amphibians to adapt to living on land, from an evolutionary standpoint: • Bones became stronger • Lungs and breathing tubes developed • The breastbone (sternum) developed a bony shield to support organs

  18. Amphibian Characteristics • As larvae, they are filter feeders or herbivores; adults are carnivores • Gas exchange occurs through skin and gills(larvae) and lungs (adults) • Adults have three heart chambers; circulation is a double loop system • Kidneys remove wastes from blood • Eggs are laid in water and then the male fertilizes them • Eggs hatch into larvae, called tadpoles • They have good vision and can sense sound vibrations

  19. Classification of Amphibians • Salamanders • Long bodies, four legs and long tails • Frogs and Toads • Do not have tails and can jump • Frogs live close to water, toads live in moist wooded areas • Caecilians • Do not have legs • Live in water or burrow in moist soil

More Related