BIO 109 Home
Questions | Answers

1. hair and mammary glands

2. Monotremes: lay eggs
Marsupials: give birth to embryonic young
Placental Mammals: retain fetus in uterus for full term and use true placenta to supply nutrients and rid wastes.

3. Rodents first and bats second.

4. Antlers: made of bone, shed annually, only males have them (except in caribou where both sexes have them. Deer have antlers.
Horns: made of bone core and keratin sheath, never shed, both sexes have them. Bighorn sheep have horns.
Pronghorns: made of bone core and keratin sheath, the keratin sheath is shed annually, both sexes have them. Only the pronghorn have pronghorns.

5. Moths (and some other insects) have developed the ability to hear bat ultrasonic chirps. They use two sensory fibers in their "ears." The A1 fiber hears the bat from a long way off (before the bat detects the moth) and the moth reacts by flying away from the bat. The A2 fiber hears the bat only at the last second, when the bat is very close, and the moth reacts by reflexively altering course which reduces predation by 40%.