Sponge spawning

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Sponge spawning
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Sponge spawning
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Coral spawning - sperm
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Coral spawning - eggs
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Coral spawning - eggs
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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

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Palolo worms swarming
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Palolo worms
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Palolo worms
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Uterine horns in some mammals
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Acanthocephalans (spiny-headed worms
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Acanthocephalan in situ
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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!

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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

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Damselflies mating
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Dragonflies mating
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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 females reproductive
  tract
• Males sometime hold on to the female while she
  oviposits
• Other males hover around the female during
  oviposition

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Onychophora
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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