reproduction in animalia. fig. 7.1 types of reproduction asexual – binary fission 1 ->2 –...
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Reproduction in Animalia
Fig. 7.1
Types of reproduction
• Asexual – Binary fission 1 ->2– Multiple fission or schizogony 1 -> many– Budding – a new organism buds off an existing
organism.– Fragmentation – organism breaks into fragments that
each for new organisms.– Parthenogenesis – ameiotic or meiotic.
Sexual reproduction
• Offspring produced from union of gametes from two genetically distinct parents.
• Dioecious – separate sexes• Monoecious – an individual have both male
and female reproductive structures – called hermaphrodites
• viviparous - give birth to live young• oviparous - lay eggs• ovoviviparity - eggs are retained inside the
female such that she gives birth to live young.
Sponges
• Asexual – buds• Sexual – Produce heterogametes – sperm and
eggs from choanocytes or archaeocytes.• Some are viviparous – fertilization is internal,
zygote is retained and receives nourishment from parent. Others are oviparous – sperm and egg released into water, zygote develops externally.
• Results in free swimming flagellated larvae.
Fig. 13.12
Craspedacusta spp.Freshwater hydrozoan
Crustacea - Daphnia
Sexual and asexual reproduction
Fig. 14.14Life cycle of human liver flukeClonorchis sinensis
Fig. 16.19Mollusca
Fig. 17.21
Annelida
Fig. 21.25
Hemimetabolous metamorphosis
Fig. 21.22
Holometabolous metamorphosis
Fish
• External fertilization• Oviparous• May be ovoviviparous, e.g. some sharks• Sexes can change, large females become
males• Some forms of pollution causes sterility in fish
Amphibians
• Tied to water through reproduction• External fertilization• Frogs – tadpole stage
• Turtles- oviparous- internal fertilization- female burry eggs- nest temperature determines sex
Birds
• Fertilization internal• Incubation external• Young precocial or altricial• Sex determination by chromosomes (Female
heterogametic)
Monotremes
Duck-billed Platypus
oviparous
Marsupials• Viviparous• Pouched• Choriovitelline placenta• Embryo encapsulated in shelled membrane• - hatch and then erodes a depression in the
placenta
Placental mammals
Fig. 8.25