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Phylum Chordata What Is A Chordate? 4 characteristics present at some stage of life 1. A dorsal, hollow nerve cord (called spinal cord in vertebrates) 2. Notochord – a supporting rod (develops into a backbone in vertebrates) 3. Pharyngeal pouches 4. Tail that extends beyond the anus General Chordate Structure Notochord Muscle Segments Tail Anus Hollow Nerve Cord Mouth Pharyngeal Pouches Nonvertebrate Chordates • Tunicates - look nothing like other chordates – The larval form has all the chordate characteristics – The adult tunicates have neither a notochord nor a tail • Lancelets are more fishlike and have a definite head containing a mouth Fish Classes: Agnatha – jawless fish Chondrichthyes – cartilaginous fish Osteichthyes – bony fish Groups of fish Fish are the first vertebrates to evolve • Jawless Fish – have not true teeth or jaws; ex: lampreys & hagfish, parasitic • Cartilage Fish – skeleton made of cartilage; ex: sharks, rays, skates • Bony Fish – skeleton made of hard, calcified tissue bone; ex: perch, goldfish Characteristics • Integumentary – Scales & paired fins • Skeletal/ Muscular – Endoskeleton - made of cartilage or bone • Circulation – 2-chambered heart; closed-single loop circulation Characteristics • Reproductive – Internal or external; – Oviparous, Ovoviviparous, Viviparous • Eggs house outside the mothers body • Born alive after developing eggs inside of mother’s body • Bear live young that are nourished by mother • Nervous – Brain, lateral lines • Respiratory – Gills Characteristics • Digestive – Variety in types of feeding; complete digestive system • Excretory – Remove ammonia from gills & kidneys Characteristics • Body Temperature – Ectothermic • Habitat – Marine & Fresh Water Bony Fish Structures Dorsal Fins Eye Lateral line Mouth Caudal fin Operculum Pectoral fin Anal fin Pelvic fin Swim Bladder Spinal Cord Reproductive organ Brain Gills Heart Liver Gallbladder Intestine Stomach Anus Amphibians Class Amphibia • Amphibians are tetrapod vertebrates (four footed) • Include all tetrapod vertebrates that are not amniotes (lay eggs on land) • Frogs, toads, salamanders, and newts Characteristics • Integumentary – Moist skin with mucus glands – Found near moist habitats to keep skin damp • Skeletal/Muscular – Endoskeleton – Adult: legs for walking or jumping; no legs – Larva: swim Characteristics • Circulatory – Adult: 3 chambered heart, closeddouble loop – Larva: 2 chambered heart • Reproductive – External fertilization; eggs must stay moist (no shell) Characteristics • Nervous – Brain; eyes w/ nictitating membrane; tympanic membrane (like a drum) for hearing; lateral lines • Respiratory – Adult: through lungs, skin, & lining of the mouth – Larva: through skin and gills Characteristics • Digestive – Complete digestive system (mouth --> anus) – Adult: carnivore – Larva: herbivore or filter feeder • Excretory – Kidneys filter wastes from blood, urine travels through ureters to urinary bladder and out through cloaca Characteristics • Body Temperature – Ectothermic (cold blooded, find heat from an outside source like the sun) • Habitat – Adult: live on land near water – Larva: live in water Lifecycle of a Frog Adult Frog Young Frog Adults are typically ready to breed in about one to two years. Frog eggs are laid in water and undergo external fertilization. Fertilized Eggs Tadpoles Tadpoles gradually grow limbs, lose their tails and gills, and become meat-eaters as they develop into terrestrial adults. The eggs hatch into tadpoles a few days to several weeks later. Evolution • The first amphibians looked similar to lobe-finned fish Groups of Amphibians • Salamanders – have long bodies & tails, most have 4 legs, usually live in moist woods Groups of Amphibians • Frogs & toads – both jump & lack tails; frogs more closely tied to water Groups of Amphibians • Caecilians – legless animals; live in water or burrow in moist soil; many have fishlike scales,resemble earthworms or snakes