Reproductive and Excretory Systems

Female Male
Diagram by Jeff Dawson.

Fertilization is internal for all turtles. Males have a single penis. During mating, sperm moves from the male into the female. Fertilization of the egg occurs in the female's oviducts. In some species, viable sperm can be stored in the female for several years. All turtles lay eggs on land. Some turtles use the same nesting spot year after year. Sea turtles are known to migrate long distances to return to the beaches were they were born. Some female sea turtles can lay up to 400 eggs in a season. Land turtles, such as box turtles, lay fewer eggs, usually between 2 and 10. Some turtles lay several clutches each season. The turtle's eggs may be leathery or hard-shelled. After laying her eggs, the female turtle covers the nest with sand or dirt and leaves the area. The female does not see the young hatch and takes no interest in caring for them. The heat of the sun, which warms the earth, hatches the eggs.

Kidneys (Both)Compact, flattened organs located just under the carapace. The kidneys are responsible for filtering the blood of the turtle and removing harmful waste products. These wastes are concentrated and sent to the bladder as urine.
Bladder (Both)Organ that stores urine.
Cloaca (Both)Cylindrical organ that opens to the outside of the turtle's body. It receives waste products from the large intestine and bladder and sperm (male) or eggs (female).
Testes (Male)(singular: testis) Male reproductive organs. Produces sperm. Located on either side of the bladder.
Penis (Male)Sperm travel down penis into female during intercourse.
Ovaries (Female)Female reproductive organs. Produce eggs. Located on either side of the bladder.
Oviduct (Female)Tube connecting ovaries with cloaca. Eggs produced in ovaries enter the oviducts. After mating, sperm from the male travel up the oviducts and fertilize the egg. The egg then continues down the oviduct into the cloaca.
Accessory Urinary BladderIn females, these organs are known to hold water. This water is used to soften the ground while digging a nest.

2001 by Jeff Dawson. All rights reserved.
Used by permission.