Lecture 23.1. Why do mammals have a winning design? Insulating fur and endothermic metabolism.2. How do animals in very old climates stay warm (two reason)? Fur, metabolism. 3. Mammals live in highly variable habitats: Arctic, Africa. Water, on the surface, on the beach, underground, tops of tree. Air. 4. Mammals gain nutrients from many different sources.5. Details about monotreme biology- how are they different from othermammals? Raise egg. 6. Size variation among mammals: Smallest of the five vertebrates. miniature, massive (blue whale), most are not big.7. Mammalian ancestors: small, shrew-like insectivorous, arboreal and nocturnal.8. Some mammals are extinct due to inheritance difficulty. Ex) large size, Predominace of human that use of ecosystem.)9. Five mammalian traits:a. Hair (including various roles of hair): homoplasious. Found in all mammals. Dolphin and whale also have it. - Insulating and endothermy allow the mammals to live in the place where is never able to live for exothermic reptiles.- Camouflage: ex) leopard, It can work in unexpected ways; predator is orange/green color-blind.- Sensory: stiff sensory hairs on dolphin’s mouth, cat whisker toavoid the object.- Defense: Echidna, hedgehog, porcupineb. Mammary glands (milk)- The gland is leading to nipples. Newborn is born without teeth, so it is facilitating sucking. - Milk: High calorie food, rapidly growing baby mammals, 50 % energy comes from fat. Perfect match for nutritional need for babyc. Endothermy- allow to live in extreme environment: Control their own body temperature. - Blood circulatory- mammalian diaphragm for improved respiration -> increased oxygen delivery.- Homoplasious for birds and mammals.d. Sweat glands: secrete liquid, not too warm, e. Placentas: for internal gestation. Only organ that animal can grow and then disposed of. Blood contact between baby and mother. 10.Mammalian teeth- Fewer teeth than other specise(fish, reptile). However, it has various teeth depending on the food. 11.Herbivores’ gut symbionts: digest cellulose. 12.Keratin (hair, claws, finger nails and hooves)- Hooves: patch for toes. For mammals running and landing on the ground- Horns: Horn of impala is composed of core bone surrounded by the keratin. Horn is attached the skull. Antler of deer is continues to grow, so get shed every year. Rodent eat antler.13. Prototherians (monotremes, egg raised mammals)a. Echidna- Hairs turn into big spine=> effective armor.- Sense of smell, good sighting and hearing.- Do not give a birth, but raise an egg hidden in the fur; Baby isslowly developing. After it hatched, it is carried around for about 50 days until it begins to develop the spine. And then, burrow it and raise it about 7 months by feeding milk. b. Platypus- No teeth. But something else in bills- Bills: sensor for food- Milk: perfect food, grow youngster, mammals only, most of mammals produce it from nipple. But platypus is a primitive mammal. Secreted through pores in the skin.- Baby: Naked, blind, tiny spike on the bills; egg tooth for breakthe shell of egg. *Echidna and platypus are the only mammals raising the egg. 14.Theriansa. Marsupials: pouch mammals. (yapok: baby hanging under side of parents, wombat, wallaby: both have pouches)- Give a birth after short gestation. - Highly undeveloped young. Finishing development by attaching their mother. - No shell develop. - Tiny and embryonic hairless baby often navigate to the pouch. b. Eutherians: (giraffe). - Much more highly developed baby with more extended internal gestation. - There is no pouch. Placental mammals. 15.Common ancestor to the eutherians appeared shortly after the dinosaurs died out.16.Rapid radiation of eutherains after dinosaurs go extinct: Because of endothermic metabolism and insulating fur, the mammals survived. Moreover, since there was no competition with dinosaurs, themammals rapidly diversify and predominate ecosystem. The radiation within this group is parallel of break up of continent in Mesozoic
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