Salamanders And Newts: Caudata

Adult salamanders live alone rather than in groups. They hide during the day under leaves, rocks, or logs and are active at night but sometimes come out on rainy days. Salamanders hunt mainly by sight but also by smell. They sit and wait for prey to come close and then capture it with an explosive motion of their tongues. The tongue action is so fast it cannot be seen by human eyes.

Salamanders live as long as thirty years in the wild. The type of life cycle and method of development vary from species to species. In many species female salamanders lay eggs in the water, and the male releases sperm on them. Fertilization (FUR-teh-lih-ZAY-shun), or the uniting of egg and sperm to start development, takes place outside the female's body. The eggs hatch into larvae that have gills and live in the water, sometimes for years, before going through metamorphosis. During the transformation the larvae lose their gills, develop lungs, grow legs, and crawl onto land. After metamorphosis, the adult salamanders spend all or most of their time on land. In some species, female salamanders guard their nests of eggs in order to protect them from predators and to keep them from drying out.

About one-half of salamander species do not have a water-dwelling larva stage. When they hatch from eggs laid on land, the young salamanders have the same body form as adults and continue to live the rest of their lives on land. In some species of salamanders, larvae that hatch from eggs laid on land wriggle to nearby water or are caught up by rising waters in the spring. They live in water for a while and then undergo metamorphosis. Still other species of salamanders live their entire lives in water with their bodies in the larva body form. Their reproductive organs do mature, however, and these salamanders do produce young.

Some male salamanders do not spread sperm on eggs but deposit a sperm packet in or near the water. The female takes the sperm into her body, and fertilization takes place inside her. In a few species of salamanders, the developing larvae stay inside the female for one or two years or even longer. These larvae go through metamorphosis inside the female. The young animals are quite large when they are born, having received their nourishment first by eating their siblings and later by eating secretions in the female.

Most salamander larvae can be classified as the pond type or the stream type. The pond type usually change form in one season and have large, feathery gills and a large tail fin. Stream-type larvae have a small tail fin, very short gills, and a flat body with short, fat legs and hard toes. These larvae may live for several seasons before going through metamorphosis.