Reproduction in invertebrates
•  Asexual
–  Produce genetically
identical offspring
–  Rapid increase in
population size
–  No need for egg
production
•  Sexual
–  Recombination of
genetic material during
meiosis
–  Recombination of
genetic material by
mixing two parents
Asexual reproduction
•  Fragmentation
•  Fission
–  Architomy
–  Paratomy
•  Budding
•  Parthenogenesis
–  2n diploid egg –  1n haploid egg
Fragmentation –regeneration
Ex, Asteroidea
Fission
Fission
Budding
•  Differentiation of
daughter before
detaching from parent
•  Local reorganization
into a small outgrowth
Colonial organisms
•  In some organisms
fission is incomplete
and thus gives rise to
colonial organisms
Parthenogenesis
Thelytokous
eggs
Arrhenotokous
eggs
Amphitokous
eggs
Parthenogenesis
Sexual reproduction
•  Gonochorism
–  (dioicy)
•  Hermaphroditism
–  (monoecy)
–  Simultaneous
–  Sequential
•  Protandrous
•  Protogynous
Sex determination mechanisms
•  Maternal
•  Genetic
•  Environmental