Reproduction in Animals

Brainstorm Do all animals reproduce similarly? No Why might different animals have different forms of reproduction? Different organs Different habitat (ie. Land, water) Different climate (tropics, rain forest, dessert) Are there any advantages/ disadvantages to reproducing at different times of the year? WHEN? and WHERE?

WHEN? Mating occurs when the environmental conditions are good to raise the young. Among most birds, mating occurs in the Spring the young are born several weeks later They reach maturity before the onset of winter Q: Why is this important in cold climates? Birds need to have reached maturity before they can migrate south for the winter

WHEN? Among most mammals, mating occurs in the fall the embryos develop in the winter the young are born in the spring Q: Why is this important in cold climates? - The newborn might not be able to survive the cold of the winter

Fertilization Fertilization: union of sperm and ovum

Reproduction in water animals Fertilization is external in animals that live in the water The female fish will lay eggs in the water. the male fish will deposit a liquid that contains sperm over the eggs The sperm swims to and fertilizes the egg The fertilized egg will divide over and over again; this is the developing embryo (young fish) Reproduction Movie

Land Animals Q: What problem might land animals encounter during reproduction? A: Dehydration Q: What adaptations have evolved in these animals to combat this? A: Internal fertilization Q: How are the reproductive systems of land animals different than those of water animals? A: 1) both males and females have special organs for the internal transfer and union of sperm and ova (egg) 2) an internal womb is required for the development of the young

What are the different forms of Reproduction? Animals can be: Oviparous: the young hatch from eggs risk?: eggs are vulnerable to predators ex. Reptiles and birds 2) Ovoviviparous: the female retains the egg until shortly before hatching or the eggs may hatch within the female’s body ex: some snakes and lizards 3) Viviparous: the young develop in the mother’s body ex: mammals

Mammals Mammals are classified into 3 groups: 1) Monotremes: egg laying ex: duck-bill platypus 2) Marsupials: their young are born in an immature state and complete their development in their mother’s pouch ex: kangaroos, koalas 3) Placentals: the young develop in the mother’s body and are nourished by the placenta ex: baboons, humans

Eureka Textbook Questions READ pages A 254 - 260 B 250 – 256; Do Questions from 1 – 6 on Handout. Hand in before you go.