Ambystoma opacum is a smaller member of the "mole salamanders" (a family of salamanders including the tiger, spotted, blue-spotted salamanders, etc.). It attains an adult length of approximately 9-10.7 cm. Sometimes called the banded salamander, because of its white or light gray bands across the head, back, and tail. Males have silvery white crossbands, which become very white during the breeding season. The female, being the larger of the two, has silvery gray crossbands. (Conant and Collins, 1998; Petranka, 1998)
Ambystoma opacum, the marbled salamander is found throughout most of the eastern United States, from Massachusetts west to central Illinois, southeastern Missouri and Oklahoma and eastern Texas, south to the Gulf of Mexico and the Carolina coast. It is absent from peninsular Florida. Disjunct populations are found in eastern Missouri, central Illinois, in northwest Ohio/northeast Indiana, and along the southern edges of Lake Michigan and Lake Erie. (Petranka, 1998)
Adult marbled salamanders live in damp woodlands, often close to ponds or streams. These salamanders are occasionally can be found around dry hillsides, but never far from a moist environment. (Flank, 1999; Petranka, 1998)
Unlike most other mole salamanders, this species does not breed in water. Adult marbled salamanders breed only in dried up pools, ponds, and ditches, and females lay their eggs under the leaves there. The eggs hatch after the ponds refill. (Petranka, 1998)
Unlike other mole salamanders which breed underwater during the spring, The marbled salamander has a very unusual reproductive strategy. Instead of breeding ponds or other water sources, in spring months, Ambystoma opacum is a fall breeder, and breeds entirely on land.
After finding his mate, the male will court with the female, often moving in a circular fashion with her. After mating the female will leave and select a small depression in the ground. This depression is usually a drying up pond or ditch. The female will lay a clutch of between fifty and one hundred eggs. Once laid, the female will remain with them to keep them moist, until nests are flooded by rain water. As soon as the autumn rains come the eggs will hatch in the depression they were laid in. If rain never comes the eggs will survive over the winter, if temperatures do not fall too low, then hatch the following spring.
Once hatched the gray colored larvae (1 cm) grow very quickly by constantly eating plankton. Large larvae, however, will eat amphibian larvae and eggs. It takes larvae marbled salamanders between 2 and 9 months to leave the water. Young juveniles are approximately 5 cm, and attain adulthood in about 15 months after leaving water. (Flank, 1999; Petranka, 1998)
Marbled salamanders spend most of their time under leaf litter or underground (up to one meter). They will defend the burrows they inhabit against other salamanders. Occasionally, adults will share burrows with each other. The only time species are in contact with one another is during the breeding season. Males will often arrive at potential sites about a week before the females. (Flank, 1999; Petranka, 1998)
Even with its small size, an adult Ambystoma opacum is a voracious, carnivorous predator, consuming large amounts of food. Small worms, insects, slugs, and even snails, make up its diet. Attracted to movement as well as odor, this species will not eat dead prey. (Flank, 1999)
Marbled salamander larvae are also active predators, and may be the dominant predators in their temporary ponds. They eat zooplankton (mainly copepods and cladocerans) when they first hatch, but add other prey to their diet as they grow, including larger crustaceans (isopods, fairy shrimp), aquatic insects, snails, oligochaete worms, and the larvae of amphibians, sometimes even other marbled salamanders. In woodland ponds larger larvae sometimes feed heavily on caterpillars that fall into the water. (Petranka, 1998)
Marbled salamanders are preyed upon by various woodland predators (snakes, owls, raccoons, skunks, shrews, weasels).
Poison glands located on the tail provide a degree of protection. (Petranka, 1998)
Marbled salamanders have no economic importance.
This species is listed as threatened by the Michigan Department of Natural Resources (DNR). In other areas it is not considered threatened and can be locally common.
David Armitage (editor), Animal Diversity Web.
Garry Rogers (author), Michigan State University, James Harding (editor), Michigan State University.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.
an animal that mainly eats meat
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
animals that have little or no ability to regulate their body temperature, body temperatures fluctuate with the temperature of their environment, often referred to as 'cold-blooded'.
the state that some animals enter during winter in which bodily functions slow down, reducing their energy requirements so that they can live through a season with little food.
fertilization takes place within the female's body
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an animal which has a substance capable of killing, injuring, or impairing other animals through its chemical action (for example, the skin of poison dart frogs).
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
small animals that float or drift in great numbers in fresh or salt water, especially at or near the surface. These serve as food for many larger organisms. (Compare to phytoplankton.)
Conant, R., J. Collins. 1998. A Field Guide to Reptiles and Amphibians of Eastern and Central North America: Third edition, expanded. New York, NY: Houghton Mifflin Company.
Flank, L. 1999. "Marbled Salamander" (On-line). Accessed November 11, 1999 at http://www.geocities.com/RainForest/2421/Marbled.htm.
Petranka, J. 1998. Slamanders of the United States and Canada. Smithsonian Institution Press.