1. Reproduction in Animals

2. Asexual Reproduction Remember, asexual reproduction means = a single living organism can produce one or many identical individuals Examples: Many invertebrates such as sponges and hydra Individuals produce buds that develop directly on the parent. Once mature, they may break off and become independent

3. Sexual Reproduction Remember, sexual reproduction means a male and female create unique offspring Male animals produce male gametes = Spermatozoa Female animals produce female gametes = ova Gametes = contain half the genetic information

4. Steps in vertebrate reproduction 1.Male gamete (50%) fuses with a female gamete (50%) 1.This fusion produces the zygote that contains complete genetic material (100%) 1.The zygote divides and transforms into an embryo made up of many cells 1.The embryo develops into a small animal 2.When the animal becomes an adult, it will produce gametes and can also reproduce

6. For sexual reproduction to be successful… 1.The male and female gametes must be in the same place at the same time 1.The zygote must obtain the nutrients and protection it needs to survive. It must also get the warmth and moisture it needs to develop.

7. Mating During mating, two individuals of an animal species unite to combine their gametes and achieve fertilization

8. Fertilization in Animals Internal and External

9. Fertilization Fertilization occurs when a spermatozoa and ovum of a single species combine (50% + 50% = 100%) Fertilization must take place in a moist environment Gametes are fragile cells that die if they dry out Moisture keeps egg membrane supple (easy for sperm to enter) Sperm can only move in a moist environment

10. Types of Fertilization External Fertilization = Gametes combine OUTSIDE the bodies of both parents Internal Fertilization = Gametes combine INSIDE the body – Sperm enter female and migrates toward the ovum

11. External Fertilization Most aquatic animals reproduce this way Ex. Sea Anemone Do not move to find mates Release gametes directly into the water Sperm and egg brought together by sea currents Zygotes become LARVAE that can swim and find food Eventually settles on ocean floor and develops into adult

12. External Fertilization Example: Fish Female fish lay eggs in a cluster (many altogether) Then the male release his gametes directly onto the eggs This is known as SPAWNING

13. External Fertilization Example: Frog Similar to in fish – male will clasp onto female and once she has laid eggs he releases his sperm over them Frogs (as well as anemones and fish) do not emerge from eggs looking like parents They undergo several stages of development first

14. Internal Fertilization Most species of land animals reproduce this way Example: Reptiles Cloaca – Opening on both males and females used in excretion of waste and sexual reproduction During mating, male and female join their cloacas and the male releases sperm into the female

15. Internal Fertilization Oviparous – lay eggs (ex. Reptiles, birds, amphibians, fish and insects) -Zygote is in a liquid environment inside the shell -Zygote becomes embryo which will develop into young animal -Egg contains all the nutrients needed for the development -When development is complete  Hatch

16. Internal Fertilization Example: Mammals Male mammals have a PENIS and deposit their sperm inside the female Except for a few exceptions, mammals do not lay eggs

17. Internal Fertilization - Mammals Viviparous – fertilized ovum completely develops inside the mother’s body  live birth Young develop more completely this way Get nutrients from the mother After birth, female provides milk for her young

18. Internal Eggs? Say whaaaat? Ovoviviparous – females keep their eggs inside their bodies until they hatch – incubation occurs inside females body and young are then born live!

19. Hermaphrodites Animals that have both male and female reproductive organs Examples: Snails, Worms Reproduce by special type of internal reproduction Both inject semen into the others genital opening and then both worms lay fertilized eggs

20. Memory Check Complete the memory check on page 256 of your textbook