Most people would not consider hanging out under rotting wood feeding on a diet of spiders, centipedes, slugs and earthworms as their ideal lifestyle. The blue-spotted salamander believes it's just grand. This salamander found throughout Michigan is common in moist deciduous hardwood areas and swamp woodlands, preferably with access to vernal ponds. However, they often persist in drier, human disturbed second growth woodlands. Their diet includes insects, spiders, worms, and other small invertebrates.
Their coloration can vary but generally they are black with turquoise or pale blue flecks and spots on the sides, limbs, belly, and tail. The belly may be black or grayish black. Adults average about 3.5 to 5.5 inches (8.9 to 14 cm) long.
Photo © Jim Harding
Note: Across much of Lower Michigan, populations of Blue spotted Salamanders often include many hybrid individuals that may appear stouter and grayer, with fewer or no blue spots on the sides. Most hybrids are triploid females. (Normal salamanders are diploid, having two sets of chromosomes in their body cells; triploid salamanders have an extra set). Hybrid populations result from the breeding of Blue-spotted Salamanders with other members of the Ambystoma genus.
Like most salamanders blue-spotted salamanders breed during the first warm spring rains of March and April. One of the best times to view salamanders is just after the ice melts in the vernal (forest ponds) wetlands. They can often be seen near the edge of the pond. After a brief courtship females will attach egg masses containing about a dozen fertile eggs onto submerged debris. One female can lay up to 500 eggs a year. See the section on breeding in "Michigan's Salamanders" for more details.
One of the most interesting adaptations of this species is its defense posture. When danger is sensed the blue-spotted salamander's tail lashes back and forth and produces a noxious secretion from two glands at the base of its tail. Even if the predator gets by this defense it may only end up a small morsel. When grabbed the salamander's tail will detach. While the predator is detained by the writhing tail the salamander zips off to safety. In time a new tail will grow to replace the lost one.
Blue spotted Salamanders are fairly common, and even occur in some of the larger urban parks and farm woodlots. They seem to be more tolerant of human habitat disturbance than the related Spotted Salamander, with which they are sometimes confused. They depend on fishless vernal ponds for breeding.