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The Vertebrates. The “Fish”. Actually made up of 6 vertebrate classes Hagfish eel-like w/o jaws, paired fins or bone. No vertebrae either Lamprey like a hagfish but with a primate vertebral column of cartilage. Cartilaginous fish Shark, rays, skates and ratfish
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The “Fish” Actually made up of 6 vertebrate classes • Hagfish • eel-like w/o jaws, paired fins or bone. No vertebrae either • Lamprey • like a hagfish but with a primate vertebral column of cartilage
Cartilaginous fish • Shark, rays, skates and ratfish • Have jaws, bones & paired fins. • Skeleton made up of cartilage • Unique scales on skin • Lobed – fin fish • Lungfish and coelacanth • Mostly extinct • Ancestors to amphibians • Fins supported by main axis of bones
The “fish” you know and love • Bony fish (Ray finned fish) • Jaws, paired fins and a skeleton of bone • Fins supported by rays of bone from central axis • Lungs (in a few) or swim bladder (controls buoyancy). Gills in most • Scales covered by mucous (reduces friction)
More fish characteristics • Closed circulatory system w/ a series of blood vessels and a 2 chambered heart • Ventricles – muscular chambers to pump blood • Atrium – collecting chambers • In fish, oxygen-rich and oxygen-poor blood mix then go to the gills for oxygenation (again). From the gills, blood goes to the body • Ectothermic • External control of body temperature
Reproduction in fish • Separatesexes • Sperm produced in testes, eggs in ovaries • Basically external fertilization and development • High mortality rate for eggs and young • If all the cod eggs in the world were fertilized and made it to becoming adults, in 2 years, the oceans would be solid cod!
Amphibians • Frogs, Toads, Salamanders and Mudpuppies and Newts • Aquatic larvae but terrestrial adults • Moist, thin skin w/o scales • Feet are webbed w/o claws • Use gills, lungs and skin for respiration • Eggs lack multicellular membranes or shells • Ectothermic
3 chambered heart • 2 atria and 1 ventricle. • Blood still mixes when it goes to the lungs and the body
Separatesexes • External fertilization and development • Metamorphosis in frogs • Eggs hatch and develop into a tadpole • Tadpoles are herbivorous • Legs and arms develop as tail is absorbed • Adults are carnivorous
Reptiles • Snakes, crocodiles, alligators, turtles, lizards and caymans • Body covered with dry scales • Terrestrial • Breathe through lungs with alveoli • Ectothermic
3.5 chambered heart (crocs have a 4 chambered heart) • 2 atria • 1.5 ventricles with a septum partially dividing the sides • Septum helps to separate the oxygen rich and oxygen poor blood • Oxygen poor blood goes to the lungs to be oxygenated and then back to the heart to be pumped to the body
The Amniotic Egg A big moment in evolution!! Allowed for fetal development out of water
Three patterns of reproduction • Oviparity - Female lays fertilized eggs Most fish, amphibians, reptiles, all birds & 2 species of mammals • Ovoviviparity – Fertilized eggs remain in body for a short time. Pit vipers, some shark (nurse shark) • Viviparity – No shells forms & young retained in body until mature. Oxygen and nutrients are transferred across a placenta Placental mammals
Birds • Feathers • Wings • Hollow boned skeleton • Endothermic – can control their internal temperature • Lungs • Oviparity
The 4 chambered HeartA double pump • 2 atria and 2 ventricles • Septum separates 1 right and left ventricles • Oxygen rich and oxygen poor blood never mix • Right side pumps deoxygenated blood from the body to the lungs • Left side receives oxygenated blood from the lungs and pumps it to the entire body • Animation
Parental care • Birds are the first time we see extended parental care given to their young • Young are born helpless and need long periods of care and development before they can leave the nest.
Mammals • Endothermic • Hair • 4 chambered heart • Double pump • Mammary glands • Extensive care given to young • Lungs • Specialized teeth (incisors, canines, premolars and molars)
Three Subclasses • Monotremes Duck-billed platypus, echidna • Oviparous – thin, leathery shells • Echidna incubate eggs in leathery pouch on belly 2. Marsupials Kangaroo, koala, opossum, Tasmanian devil Embryo develop for short time in uterus then emerge & go into marsupian to complete development
Placental MammalsHumans, dogs, dolphins, rodents • Viviparous– give birth to live young • Embryo gets nourishment via a placenta through the umbilical cord • After birth, young feed milk via mammary glands • Internal fertilization, internal development