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PHYLUM CHORDATA. Phylum Chordata Characteristics. All chordates at some point in their life cycle have: -dorsal hollow nerve cord (just above the notochord)
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Phylum Chordata Characteristics • All chordates at some point in their life cycle have: • -dorsal hollow nerve cord (just above the notochord) • -notochord (Strong, flexible, rodlike structure called a notochord at some point in their lives usually replaced by a backbone in adults)) • pharyngeal pouches • tail extending beyond the anus • bilateral symmetry
Phylogeny of Chordates Invertebrate ancestor
Phylum Chordata • Divided into 3 subphylum: • Subphylum Vertebrata • Vertebrates • Subphylum Tunicata • Tunicates, ex. Sea squirts • Subphylum Cephalochordata • Lancelets – small fish-like creatures that live at the bottom of the ocean
Phylum Chordata Subphylum: Vertebrata -About 96% of chordate species are vertebrates. -Vertebrates have a strong supporting structure called the backbone, made of segments called vertebrae. Besides support, the backbone protects the spinal cord. -The top of the spinal cord grows into a brain. - Have a skull that protects the brain - Vertebrates have an endoskeleton made of living cells that grows with the organism (internal skeleton made of cartilage and bone)
7 Classes of Subphylum 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 • Class Amphibia [am-fib-ee-uh] – amphibians ex: frogs *most have an aquatic larval stage • Class Reptilia [rep-til-ee-uh] – reptiles ex: snakes *reproduce on land • Class Aves [ey-veez] – birds *have feathers and fly • Class Mammalia[ma-ma-leea] – mammals *hair or fur and develop internally and nurse off milk after birth
Fish Agnatha: jawless fish Chondrichthyes: cartilage fish Osteichthyes: Bony fish
Amphibians Frogs Toads Newts Salamanders Caecilians
Reptiles Snakes Lizards Crocodilians Turtles Tortoises Tuatara
Aves: The Birds
Subphylum Tunicata / Subphylum Cephalochordata • (Nonvertebrate Chordates) • These animals have no backbone, but do have a notochord. • Also have a dorsal hollow nerve cord, pharyngeal pouches and a tail. • Soft bodied marine organisms • Although very different from vertebrates, they are distant relatives
Urochordata: The Tunicates -Filter-feeders (larval and adult) -Name comes from the tough covering called a tunic -Called sea squirts -Larvae have all four chordate characteristics -Adult tunicates have no notochord or tail
Tunicate Larva -Notochord -Hollow dorsal nerve cord -Pharyngeal pouches -Tail
Cephalochordata: Lancelets - Small fish-like animals that live in the sandy bottom. -Have a head region with a mouth. -Lancelets take water into their pharynx and pick out food. -Pharynx has up to 100 pairs of gill slits -Have a circulatory system but no heart. Blood is moved by the vessels.