Adult spotted salamanders are 15-25 cm in total length, and females tend to be larger than males. Compared to other salamanders, the body is stout with a broadly rounded snout. The sides of the head are often swollen at the back of the jaw. The legs are large and strong with four to five toes. (Petranka, 1998)
When they leave their ponds, spotted salamanders are black, dark brown, or dark grey on their backs, and the belly of these salamanders is a pale greyish-blue. The common name comes from two rows of yellow or orange spots which run from the head to the end of the tail. Spotted salamanders with no spots are sometimes found, but are very rare. (Conant, 1975; North American Reporting Center for Amphibian Malformations, 2003; Petranka, 1998)
Spotted salamanders have poison glands in their skin, mostly on their backs and tails. These glands release a sticky white toxic liquid when the animal is threatened. (Petranka, 1998)
When baby spotted salamanders hatch, they have front legs (unlike frog tadpoles), frilly red gills on the sides of their neck, and their bodies are dull green on top and very pale, almost white, underneath. Their tail are green too, and have little dark specks or blotches on them. (Petranka, 1998)
Spotted salamanders are found in eastern North America. Their range extends from Nova Scotia and the Gaspé Peninsula west to the northern shore of Lake Superior, and south to southern Georgia and eastern Texas. The spotted salamander is absent from most of southern New Jersey, the Prairie Peninsula in Illinois, eastern North Carolina, and the Delmarva Peninsula. (Petranka, 1998)
Adult spotted salamanders live in forests, near ponds where they can lay their eggs. They are not often seen, because they spend most of their time hiding in dead leaves, under logs, or in tunnels under ground. (North American Reporting Center for Amphibian Malformations, 2003; Petranka, 1998)
Spotted salamanders need to lay their eggs in freshwater ponds that don't have fish in them. Often these are small ponds that form when snow melts in the Spring but dry up in Autumn. (Georgia Museum of Natural History, 2000; North American Reporting Center for Amphibian Malformations, 2003; Petranka, 1998)
Spotted salamanders go through several stages over their lifetime. Female salamanders lay their eggs under water, and the larvae that hatch from the eggs are aquatic, with gills for taking oxygen from the water, weak legs and a broad tail for swimming. Larvae feed and grow in the water, and then metamorphose into an juvenile form with lungs and strong legs. Juveniles live on land, and after 2-3 years they mature into adults that can reproduce. (Petranka, 1998)
This species has relatively long incubation time in comparison to other salamanders. It takes 4-7 weeks for the eggs to hatch, depending both the temperature of the water they are in, and whether the eggs are laid in shady or sunny areas. (Petranka, 1998)
Spotted salamander larvae are 12-13 mm long when they hatch, with feathery gills and only their front legs present
Larvae grow quickly and transform within 2 to 4 months after hatching. Average size after metamorphosis ranges between 27 and 60 mm, depending on the conditions in the pond. The yellow and orange spots are usually acquired within a week following transformation. (Petranka, 1998; Petranka, 1998; Petranka, 1998)
Spotted salamanders begin migration to breeding ponds at night, during the first rain following the thaw of snow. Males respond more quickly to the rain and move faster than do the females, therefore they arrive to the pool first. They also stay longer in the ponds than females do, probably to increase their chances of fertilizing more eggs each year. The number of males present in the breeding pools is greater than the number of females, so when the females arrive the males swim about vigorously, rubbing and nosing each other. Males produced blobs of sperm called spermatophores (up to 80 per male), and the females take these spermatophores into their bodies to fertilize their eggs. Each male may fertilize several females, and each female may take up spermatophores from several males. (Petranka, 1998)
Male spotted salamanders may compete with other males for the chance to fertilize females. They push other males away from females, produce as many spermatophores as they can, and sometimes cover other males' spermatophores with their own. (Petranka, 1998)
It takes several years for spotted salamanders to become reproductively mature, and the time required is strongly affected by the climate where they live. In the warmer parts of their range they may be ready to breed in 2-3 years, but further north they males may take 5 or 6 years and females as many as seven years.
Females lay compact egg masses that are attached to submerged objects. The egg mass is covered with thick, clear or milky-white jelly. Each female lays approximately 100-300 or more eggs per year, in several separate masses. Reported averages are about 200 eggs per female per year. (Petranka, 1998)
See the "How do they behave?" section for more information about what spotted salamanders do to reproduce.
Male spotted salamanders don't take care for their offspring. Females put energy and nutrients into their eggs to feed the embryos before the hatch, and when they lay the eggs, they cover them with protective jelly. They also are careful to choose the right place to lay their eggs. After they lay their eggs, they leave the pond and don't provide any more care for their offspring.
Most spotted salamanders (more than 90%) die before they transform and leave their pond, either because their pond dries up, or they are killed by predators or disease. If they do survive and make it out of the pond, they typically live about 20 years in the wild, though some have been reported as old as 30. Their chance of survival from one year to the next is much much higher after they transform. (Petranka, 1998)
Spotted salamander larvae hide in the litter at the bottom of the pond when they detect potential predators, but when not threatened by larger animals, they are aggressive predators themselves. (Petranka, 1998)
After they transform from aquatic larvae to the terrestrial adult form, spotted salamanders disperse from their ponds on rainy nights. They find refuge in animal burrows and under logs and rocks. Most live within 100 meters of their breeding pond, though a few have been found as far as 250m. This species is not believed to be a strong digger, mainly using existing burrows and crevices, though some may enlarge or modify the tunnels they find. Most hide within a few centimeters of the soil surface, but some have been found as deep as 1.3 meters below the surface of the soil. (Petranka, 1998)
When ready to breed, spotted salamanders try to return to the pond they hatched in, and even if another pond is closer they will try to go to their own pond. They are able to locate the pond even if moved hundreds of meters away. It is not known exactly how they do this, but chemical sense (smell and taste) are probably important. They often arrive and leave their pond at the same spot, and may follow the same path every time they breed. (Petranka, 1998)
Adult spotted salamanders are quite sedentary, only moving as far as necessary to find food and cool moist refuges underground. They only emerge from their burrows if they can't get enough food below ground, and then only on moist or rainy nights. They stay hidden if conditions are too cold, too warm, or too dry. (Petranka, 1998)
Spotted salamanders tend to stay in an area of 8-15 square meters of forest floor. They respond aggressively to other spotted salamanders that they encounter in their burrows or feeding area, but it's not known if they maintain or mark a territory. (Petranka, 1998)
These salamanders locate prey by smell and sight. Their vision is probably best for detecting motion in low light. Sense of smell is important in orienting spotted salamanders to their burrows and to their home pond, as are visual and tactile information. It is believed that home pond odors are preferred compared with foreign pond odors. (Petranka, 1998)
During courtship, males nudge and rub females, probably communicating with both touch and smell. Females are attracted by the chemical scents given off by males in the water. (Petranka, 1998)
Salamander larvae are aggressive predators. They are generalists, eating whatever small animals they can catch. When they first hatch they feed mainly on small insects, and branchiopod crustaceans like Daphnia and fairy shrimp. As they get larger they take larger prey, including isopods, amphipods, larger insects, frog tadpoles, and other salamander larvae. In times of overcrowding, usually when the vernal pools start to dry up, spotted salamander larvae may become cannibalistic and attack members of their own species. (Petranka, 1998; The Vernal Pool Association, 2004)
The adult spotted salamander uses its sticky tongue to catch food. Their diet consists mainly of forest floor invertebrates, including earthworms, snails and slugs, millipedes, centipedes, spiders, and a wide variety of insects. They sometimes also eat smaller salamanders, such as the red-backed salamander, Plethodon cinereus. (Petranka, 1998)
The egg masses are covered in a thick jelly that helps keep them from drying out, and protects them from some egg-eating predators, such as leeches and sunfish. A special species of one-celled green algae grows on the eggs too, it gives extra oxygen to the eggs and may help hide the eggs with its green color. (Petranka, 1998)
Despite this protection, a number of predators eat spotted salamander eggs: adult newts, wood frog tadpoles, crayfish and some species of caddisfly (especially Ptilostomis postica and Banksiola dossuaria) and midges in the genus (Parachironomus). These predators are so effective that in some years up to 90% of eggs may be killed before they hatch. (Petranka, 1998)
Spotted salamander larvae are also in danger. They are eaten by fish, frogs, and also aquatic insects. (Petranka, 1998)
Adult spotted salamanders are preyed upon by larger animals, including skunks, raccoons, turtles, and snakes, especially garter snakes (genus Thamnophis). Like many other salamanders, adult spotted salamanders have special glands on their back and tail that produce a bad-tasting poison. The bright spotting on these salamanders is a warning to predators of their bad taste and poisonous protection. (Petranka, 1998)
Adult spotted salamanders respond to attack by arching the body and sometimes butting with the head or lashing with the tail, probably to expose the predator to as much poison as possible. They sometimes bite, and individuals of all sizes may also make sounds when attacked. (Petranka, 1998)
Spotted salamanders can be important to the community of species that live and breed in vernal pools, affecting the abundance and diversity of other species in the pools, especially other amphibians. Gray treefrogs (Hyla chrysoscelis and Hyla versicolor) avoid breeding in ponds with spotted salamanders in them, and depending on the timing and size of the other species present, spotted salamanders may reduce the population of other Ambystoma species in their pools. (Petranka, 1998)
Spotted salamanders may help control insect pest species, including mosquitoes that breed in their ponds. (Petranka, 1998)
The spotted salamander is still a fairly common species, but its populations are particular vulnerable because of their dependence on vernal pools for breeding. Acidic precipitation has a negative effect upon their embryos, and habitat destruction is a problem, especially as it isolates populations from each other. The species is rated "of Least Concern" by the IUCN, and is not listed by the U.S. Endangered Species Act, in the CITES appendices, or by the State of Michigan. (Petranka, 1998)
The spotted salamander is still a fairly common species, and it is not considered endangered. However, the species depends on vernal pools to survive and reproduce, and this habitat is threatened by acid rain and deforestation. The species is rated "of Least Concern" by the IUCN, and is not listed by the U.S. Endangered Species Act, in the CITES appendices, or by the State of Michigan. (Conant, 1975; Petranka, 1998; The Vernal Pool Association, 2004)
Lauren Pajerski (author, editor), Undergraduate Research Opportunity Program, University of Michigan, George Hammond (author, editor), Animal Diversity Web.
Nichol Stout (author), University of Michigan-Ann Arbor.
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