Which reproductive adaptation is characteristic of most terrestrial vertebrates but not of most aquatic vertebrates?
A. Motile gametes.
B. External development.
C. Internal fertilization.
D. External fertilization.
Most vertebrate animals that live on land have an adaptation that allows internal fertilization, whereby the male penis inserts sperm directly in the female body. This is advantageous since sperm need liquid to swim and the moist female reproductive tract provides this. Aquatic vertebrate animals live in water so sperm can easily be deposited in the water and swim to the female reproductive tract.