T or F. Animals reproduce sexually and plants reproduce asexually. F. The vast majority of both animals and plants reproduce sexually.
Animal Reproduction General Rule The more evolved the species, the better the success of reproduction.
Asexual Reproduction Fission- “mitosis” of one celled animals. Fission- “mitosis” of one celled animals. Budding- growth of new organism off the body of parent. Budding- growth of new organism off the body of parent. Sponge
Asexual Reproduction n Regeneration- growth of a new organism or body part by “mitosis”. n Parthenogenesis- (rare) development of an unfertilized egg into adult.
Gonads by Gametes “meiosis” (sex cells) “meiosis” (sex cells) Ovaries Eggs Testes Sperm Sexual Reproduction (sex organs)
Most species of animals have separate sexes, however a few are Hermaphroditic- both sex organs on the same animal.
Fertilization- union of sperm and egg to create a new baby cell. n External Fertilization- out- side the female body. Must occur in water. n Internal Fertilization- inside the female body.
Development(Embryology) n External- outside the female body. Riskier. Must produce more embryos. n Internal- inside the female body. Safer. Fewer embryos needed.
External Development is...
External Development Most species spend a short time as an egg, but do Metamorphosis - change A. Incomplete- egg, nymph, adult or B. Complete- egg, larva, pupa, adult
The Shelled Egg Yolk-food Albumen-food Waste sac Embryo Shell gas gas exchange exchange bs16309+
Internal Development Mammals only Less dangerous,fewer embryos. No metamorphic stages, but a longer, gradual development More complicated bodies are created.
Marsupials,such as possums and kangaroos develop internally for as little as 13 days!!!
The time of internal development (Gestation or Pregnancy) varies amongst different mammals. 21Days 9 mos. 22 mos. (Yikes!)
Yes, humans are mammals, too!! Time for humanbiology!!