1. Animal Reproduction Sexual & Asexual By Diana L. Duckworth
Rustburg High School
Campbell County

2. Asexual Reproduction
Budding – small part of parent’s body grows into new organism
Genetically
identical
clones

3. Asexual Reproduction
Regeneration – parent separates into two or more pieces & each piece forms new organism
In some instances just a new part grows
Sponges, sea stars, jellyfish, planaria
Also be clones

4. Asexual Reproduction
Parthenogenesis – growth & development of embryo without fertilization by male
Population all female
Many insects; lizards, salamanders, fish, turkeys

5. Sexual Reproduction – gametes from opposite sexes unite
Species with sexual reproduction are said to be dioecous – separate sexes
Often exhibit distinct sexual dimorphism – males and females look different
Sperm (male gamete) formed by meiosis in testes
Eggs (female gamete) formed by meiosis in the ovary

6. Mating
Mating – male & female join together to ensure fertilization; not essential to sexual reproduction

7. External Fertilization
Males & females release sperm & eggs into the environment – sperm & egg join outside the body
Males & females may come into close proximity
Eggs & larvae develop outside the body
Many gametes produced; many zygotes formed
Usually aquatic

8. External Fertilization – e.g. Salmon

9. Internal fertilization
Joining of sperm & egg inside the body after mating
Ensures selection of mate (not random); promotes diversity
Parents protect and care for young
Does not require water; can occur on land
Less sex cells produced; increases probability of successful reproduction
Common in birds, reptiles & mammals

10. Internal fertilization; external development
After fertilization, larvae (embryo) are released & development occurs outside female body
Example: Barnacles

11. Internal fertilization & development
Females put large amounts of energy into development of embryo – very few in litter or clutch – different schemes
Eggs in “shell” are laid and either abandoned or nurtured in nest

12. Various levels of parental care

13. Internal fertilization & internal development of eggs; followed by live birth

14. Internal fertilization, internal development of embryo to fetus, live birth
In seahorses, eggs are deposited in the male
where they are fertilized and develop. Babies
born live.

15. In most species, it is the female who carries the developing fetus to birth…

16. Hermaphrodites Organisms that change sex in order to reproduce
Crepidula fornicata – a snail