Salamander, Marbled


Ambystoma opacum


Adult length of approximately 9-10.7 cm; males are smaller than females, and have silvery white crossbands. During the breeding season, the crossbands become very white and glands around the male’s cloaca become swollen. Females are larger, and have silvery gray crossbands. There is considerable variation in the crossbanding pattern, as in some individuals they are extensively connected, and in others the connection is minimal. A terrestrial mole salamander, the marbled salamander is also identified as having wide, protruding eyes, prominent costal grooves, thick arms, and rounded tails.

Family

Ambystomatidae

Order

Caudata

Class

Amphibia

Range

Eastern USA from New Hampshire southward to northern Florida, west through southeastern New York to Lake Michigan region, south to eastern Oklahoma and eastern Texas. It is absent from most of the Appalachian Mountains.

Habitat

Damp woodlands, often close to ponds or streams

Life Expectancy

8 – 10 years or more

Sexual Maturity

Females – approximately 4 years; males – 17 to 26 months

Diet

In the wild, they feed on small worms, insects, slugs, and snails; in the zoo, they are fed small crickets, and occasionally wax worms and red wiggler worms.

Status

IUCN – Least Concern; MI - Threatened

Behaviors

The marbled salamander is a mole salamander and a solitary species, spending most of its time under leaf litter or underground. It is thought that the species will defend burrows they inhabit against others of the same species. Occasionally, adults will share burrows with each other. Adults do, however, tend to be more aggressive towards each other when food is scarce. 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. Even with its small size, an adult marbled salamander is a voracious, carnivorous predator, consuming large amounts of food. 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. Unlike most others in this family, the marbled salamander has a very unusual reproductive strategy. Instead of breeding ponds or other permanent water sources, in spring months, the marbled salamander is a fall breeder (September – October in the north & October – December in the south), and breeds entirely on land. After finding his mate, the male will court the female, often moving in a circular fashion with her. The male will then proceed to undulate his tail, and raise his body. Following this, the male will deposit a spermatophore onto the ground. If interested, the female will then proceed to pick it up with her cloacal. Afterward, the female will venture off and select a small depression in the ground. This depression is usually a reduced pond, or dried bed of a ditch or temporary pond. The female will lay a clutch of between 50 to 100 eggs and she will remain with them to guard them and keep them moist, until nests are flooded. This unusual strategy virtually ensures that the young marbled salamanders are the very first salamanders to hatch each year, which may give them a considerable advantage over potential competitors. As soon as the autumn rains come the eggs will hatch. If rain never comes the eggs remain dormant through the winter if temperatures do not fall too low, then hatch the following spring. Once hatched, the gray colored larvae grow extremely quickly, eating primarily macrozooplankton. Large larvae, however, will eat amphibian larvae and eggs. The timing on metamorphosis depends on geographic location (usually between April and May). Those that are found in the South can go through metamorphosis in as little as two months. Those in the northern climates generally take between eight to nine months. Young juveniles are approximately 5 cm, and attain sexual maturity in about 15 months after metamorphosis.

Adaptions

Poison glands located on the tail provide a degree of protection from predators.

Special Interests

Marbled salamanders are preyed upon by various woodland predators (snakes, owls, raccoons, skunks, shrews, weasels).

Folklore

Conservation

This species is listed as threatened by the Michigan Department of Natural Resources. In other areas it is not considered threatened and can be locally common. Declining populations in the Great Lakes region can be attributed to both declining habitat and the effects of widespread temperature cooling after a warmer postglacial climate brought them into the area. The marbled salamander is listed as Least Concern by the IUCN in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. Threats to local populations likely include intensive timber harvesting practices that reduce canopy closure, understory vegetation, uncompacted forest litter, or coarse woody debris (moderately to well-decayed) in areas surrounding breeding sites. Breeding sites are vulnerable to destruction and degradation through draining and filling, and many are being isolated by habitat fragmentation, which could eventually result in deleterious levels of inbreeding and reduced chances of re-establishment of locally extirpated populations. Thousands of local populations already have been eliminated by habitat loss, and more will be lost in the future. This species is sometimes found in the international pet trade but at levels that do not currently constitute a major threat. Needed conservation measures include protection of vernal pools and adjacent wooded areas up to at least 218 – 273 yards (200-250 m) from the pools. Also, regulatory agencies should attempt to minimize forest fragmentation.

Jacksonville Zoo History

Marbled Salamanders have been part of the Jacksonville Zoo’s animal collection for all but one year since 2000.

Exhibit

Wild Florida