1. Sponge spawning

3. Coral spawning - sperm

4. Coral spawning - eggs

6. Palolo worm (polychaete annelid) Consist of anterior atoke and a posterior epitoke On two or three nights, epitokes break free from the atokes and swim to the surface Mass spawning of palolo worms

7. Palolo worms swarming

8. Palolo worms

10. Uterine horns in some mammals

11. Acanthocephalans (spiny-headed worms

12. Acanthocephalan in situ

13. Acanthocephalan reproduction Males have an eversible penis After mating with a female, the males neatly cap the female gonopore with cement Males will also attempt to cement shut the gonopores of other males!

14. Last male advantage In a number of animals with internal fertilization, the last sperm to enter the female reproductive system have the advantage Examples are birds and insects

15. Damselflies mating

16. Dragonflies mating

17. Dragonflies and damselflies Male curls his abdomen to transfer sperm from the ninth abdominal segment to accessory genitalia on the second abdominal segment The male and female adopt the wheel position to transfer sperm to the female Before copulating, the male will scoop out any pre-existing sperm from the female’s reproductive tract Males sometime hold on to the female while she oviposits Other males hover around the female during oviposition

18. Onychophora

19. Onychophora reproduction Male deposits a spermatophore (a protective structure enclosing sperm) on the forest floor A female stumbles across a stomatophore and appresses her ventral side to the spermatophore The spermatophore causes her ventral body wall to rupture (ouch!), providing a means for sperm to enter her body