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Unformatted text preview: mammals into three major groups 1) Holotheria – monotremes (fig. 31-26) – (oviparous) mothers lay eggs and they either have a small pouch or nest; have mammary glands without teats, so milk drips on to fur and baby licks milk off of fur • Duck-billed platypus • Echidnas (spiny anteater) 2) Metatheria – marsupials (fig. 31-27) – (viviparous) marsupium (pouch); the young are nourished from a yolk and from some things from the mothers; after a few weeks being inside the mother, the young is expelled from the mother and lives in the sac where is attached to a nipple and gets food that way • Kangaroos • Koala s • Possums 3) Eutheria –placental mammals (fig. 3-29) – (viviparous); have a placenta (partially from embryo, partially from mother); babies are born at a more mature stage than other mammals (get nourishment from placenta) • Humans • Zebra • Elephants...
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This note was uploaded on 05/30/2008 for the course BS 131 taught by Professor Smith during the Spring '08 term at University of the Sciences in Philadelphia.
- Spring '08