This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
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...
View Full Document
- Spring '08