MONOTREMES

1
MONOTREMESEgg laying

• Duckbilled Platypus
• Anteater
• Echidna

2
MARSUPIALSPremature babies develop in pouch

• Found in Australia/New Guinea
• Kangaroo
• Wallaby
• North America
• oppossum

3
PLACENTALEmbryos nourished inside mother by
placenta

• 95 of all mammals are placental

http//www.scienceclarified.com/images/uesc_04_img
0230.jpg
4
Ways offspring enter world

• OVIPARITY- Reproductive tract encloses egg in
  tough protective shell
• Eggs deposited outside body to hatch
• EX Reptiles birds mammals (monotremes)

5
Ways offspring enter world

• VIVIPARITY-
• No shell around egg
• Eggs retained in body
• Nourished by mother through placenta
• Offspring are born alive
• Ex mammals some reptiles

6
Ways offspring enter world

• OVOVIVIPARITY-Eggs laid shortly before hatching
  or hatch inside femaleNourishment inside mom
  comes from egg yolk not mother
• Ex Some reptiles (snakes)

http//www.naturealmanac.com/archive/hatching_rept
ile/clutch_of_eggs.jpg
7
OVIPARITY OVOVIVIPARITY VIVIPARITY
SHELL? NO SHELL?
Embryo grows?
Food comesfrom?
Seen in?
SHELL
NO SHELL
SHELL
OUTSIDE
INSIDE
INSIDE
EGG
MOTHER
EGG
Birds, Reptiles, Few mammals
Mammals, few reptiles
Reptiles