Animal Reproduction
I.
Asexual = usually via mitotic cell division
A. fission – splitting into 2 new organisms (invertebrates)
B. budding – new organisms split from existing one (hydra)
Stony corals are cnidarian colonies of 1000’s of individuals
C. gemmules in sponges – specialized sponge cells migrate together and get surrounded
by a protective coat
D. fragmentation
Sponges, cnidarians, tunicates, annelid worms
Often associated with regeneration
II.
Asexual and/or Sexual reproduction
A. Aphids, rotifers, Daphnia produce 2 kinds of eggs:
One kind is fertilized (this sexual repro takes places during seasons of enviro stress
One kind develops by parthenogenesis – egg develops without fertilization
Adults are often haploid
Egg cells do not undergo meiosis
B. Honey bees
Drones are result of parthenogenesis
Female worker bees and queens are produced via sexual repro
C. Whiptail lizards – produced solely via parthenogenesis – NO males of this species
Mating behaviors – one female will play role of the male
Ovulation is enhanced by these courtship rituals
D. Hermaphroditism (Greek god and goddess: Hermes and Aphrodite)
Each individual has both male and female reproductive systems
May self fertilize or fertilize another: earthworms – each animal donates and
receives sperm
Sequential hermaphroditism: individual reverses its sex during its lifetime
Protogynous – female first
Wrasses live in harems with one male; if male dies, largest
female turns into new male
Protandrous – male first
III.
Sexual reproduction
External fertilization
Frogs and salamanders
Fish
Internal fertilization
Lizards (hemi-peni)
Birds - cloaca