Life Sciences Term 1

EXTERNAL FERTILIZATION   

• The sperm cell fuses with the egg cell outside the body of the female.
• The sperm cells are discharged (released) directly into water.
• Examples are aquatic animals like frogs, sponges, jellyfish, worms and fish.
• A mass of amphibian eggs, appearing as small black spots, is contained within a gelatinous mass while they incubate in a freshwater pond.
• Eggs deposited in this fashion receive little or no parental protection and will soon hatch into small, wriggling tadpoles.

INTERNAL FERTILIZATION

• The sperm cell from the male is transferred into the female by copulation (sexual intercourse).
• The sperm cell then fuses with the ovum inside the body of the female.
• Examples : terrestrial mammals, birds and insects.
• Terrestrial vertebrates clasp each other tightly during copulation.
• The male deposits his sperm into the female’s reproductive tract.
• For the giant Galápagos tortoises mating may take hours and is initiated by the male, who
•    bangs his shell against that of the female to get her attention.
• These animals mate in the spring