Olms and Mudpuppies: Proteidae

Mudpuppies crawl slowly over the bottoms of streams and lakes, but they can swim rapidly when frightened. In captivity, mudpuppies are secretive and hide under any available object, including one another. They appear to be repelled by light. In water with a low amount of oxygen, mudpuppies constantly fan their gills, which can become large, bushy, and bright red. Under such conditions, the mudpuppies often rise to the surface to take gulps of air. In water with plenty of oxygen the gills tend to be held motionless against the sides of the neck and eventually shrink. There is some evidence that mudpuppies are capable of homing behavior. Olms are friendly to one another, at least when they are not breeding, and tend to group together in deep cracks in the cave walls. Scientists believe olms use chemical sensors to mark and find their home shelters.

Scientists know little about how olms and mudpuppies reproduce. The breeding season for mudpuppies is in the fall or winter, depending on the species and where the animals live. Males that are ready to mate have a swollen cloaca and a pair of enlarged finger-like structures that stick out toward the rear of the body. The cloaca (kloh-AY-kuh) is the chamber in some animals that holds waste from the kidneys and intestines, holds eggs or sperm about to be released to the outside, holds sperm entering a female's body, and is the passage through which young are born.

Breeding in olms does not appear to be related to the seasons, reflecting the stability of their underground habitat. Olms seem to be much more territorial than mudpuppies during breeding. All species for which information is known use some kind of mating ritual in which the males and females stimulate each others' cloacas. The male then releases a bag of sperm, which the female picks up with her cloaca. The female may store sperm in special structures inside her cloaca for six months or more. Fertilization (FUR-teh-lih-ZAY-shun), or the joining of egg and sperm to start development, takes place inside the female's body. When the female lays them, the eggs usually attach to the bottom of an object such as a rock or a log, and the female guards them.

The eggs of olms and mudpuppies hatch two to six months after they are laid, depending on the species and the temperature. The larvae develop gradually into adults without going through metamorphosis. Scientists do not know when mudpuppies are old enough to reproduce, but olms can reproduce when they are seven years old. Scientists believe olms and mudpuppies live nine to sixty years.