Sperm nucleus enters the egg and moves to the egg nucleus. The 2 nuclei join together and then form a zygote.
Animals that breed in the water
Many hazards in the environment
Sperm and egg may not meet
Eggs or offspring may be eaten
May die due to environmental conditions
Large number of sperm and egg are released to overcome hazards
Hormones control behavior to have sperm and egg released at the same time.
Some aquatic animals
Requires specialized sex organ to carry sperm to body of female
Watery environment needed for sperm to swim to the egg
After fertilization, zygote is enclosed in a protective shell and released OR remains and develops in female body
Turtle laying eggs
Fewer eggs needed
Increased chance of fertilization
Parthenogenesis – development of unfertilized egg into an adult.- Bees & Wasps