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.
Range lifespan
Status: wild: 30 (high) years.
Typical lifespan
Status: wild: 20 (high) years.
Average lifespan
Status: captivity: 25.0 years.
Spotted salamander defense begins immediately following laying of eggs. The eggs are laid in masses that are covered in a thick, firm, jelly, overcoat to protect against some predators (e.g. leeches and sunfish) and from dehydration, should the egg mass be temporarily exposed by sinking water levels. There is a particular species of unicellular green alga (Oophila ambystomatis) that grows on and in the jelly. The algae provides extra oxygen to the developing embryos, and may help camouflage the egg mass as well.
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.
Spotted salamander larvae are also heavily preyed upon. Hatchlings are eaten by those aquatic creatures previously mentioned and also various aquatic insects, fish, wading birds, other Ambystoma species, and snakes. Hatchlings raised in laboratories often die from protozoan infections as well.
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 secrete a milky toxin from glands on the back and tail for defense against predation. The bright spotting on these salamanders functions as a warning to predators of their toxic defense.
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.
Known Predators:
Anti-predator Adaptations: aposematic
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.
The background color of metamorphosed spotted salamanders can be black, dark brown, or dark grey, while the bottom half and under-surface of the limbs are a pale slate gray. On either side of the mid-dorsal line of the body are large, round, yellow or orange spots. The spots may vary in number from 24 to 45, and they are arranged in two irregular rows running along the sides from the head to the tail. Unspotted individuals do occur but are rare.
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.
When they hatch, the larvae of this species are 12-17 mm long. Their dorsal surface is dull olive green, and they remain a dull greenish color until they transform into the adult form. The underside of larvae is nearly white, and tail is finely stippled or mottled, with dark pigment near the tip.
Range length: 150 to 250 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; poisonous
Average mass: 12.84 g.
Average basal metabolic rate: 0.005 W.
Adult spotted salamanders are most abundant in deciduous bottomland forests along rivers, but can be found in upland mixed or coniferous forests if the climate is sufficiently damp and there are ponds suitable for breeding. Adults are rarely seen because they spend most of their time hiding in leaf litter, under fallen wood, or in tunnels below ground.
Like most Ambystoma salamanders, spotted salamanders lay their eggs in fresh water, but only in ponds and pools that lack fish. They often use temporary vernal pools.
Habitat Regions: temperate ; terrestrial ; freshwater
Terrestrial Biomes: forest
Aquatic Biomes: lakes and ponds; temporary pools
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.
Biogeographic Regions: nearctic (Native )
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.
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.
Animal Foods: amphibians; insects; terrestrial non-insect arthropods; mollusks; terrestrial worms; aquatic or marine worms; aquatic crustaceans; zooplankton
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods); planktivore
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.
Mutualist Species:
Spotted salamanders may help control insect pest species, including mosquitoes that breed in their ponds.
There are no known adverse effects of Ambystoma maculatum on humans.
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.
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.
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.
Development - Life Cycle: metamorphosis
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.
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.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
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.
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.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; tactile ; acoustic ; chemical
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.
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.
Mating System: polygynandrous (promiscuous)
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.
See the Behavior section for more details on breeding behavior.
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.
Breeding interval: Spotted salamanders breed once yearly
Breeding season: Eggs are laid in winter or early spring, starting in late December in the southern portion of the species' range, and as late as early May in Nova Scotia
Range number of offspring: 100 to 370.
Average number of offspring: 200.
Range time to hatching: 4 to 7 weeks.
Range age at sexual or reproductive maturity (female): 2 to 7 years.
Range age at sexual or reproductive maturity (male): 2 to 6 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Male spotted salamanders provide no parental care. Females invest nutrients in provisioning their eggs with yolk and supplying them with protective layer of jelly. They also make an effort to lay the eggs in a suitable location, usually on submerged tree branches or aquatic plants. There is no further investment after the eggs are laid.
Parental Investment: pre-fertilization (Provisioning)
The spotted salamander or yellow-spotted salamander (Ambystoma maculatum) is a mole salamander[2] common in eastern United States and Canada.[1] It is the state amphibian of Ohio and South Carolina. The species ranges from Nova Scotia, to Lake Superior, to southern Georgia and Texas.[3] Its embryos have been found to have symbiotic algae living in and around them,[4] the only known example of vertebrate cells hosting an endosymbiont microbe (unless mitochondria are considered).[5][6]
The spotted salamander is about 15–25 cm (5.9–9.8 in) long.[7] With Females generally being larger than males.[8] They are stout, like most mole salamanders, and have wide snouts.[3] The spotted salamander's main color is black, but can sometimes be a blueish-black, dark gray, dark green, or even dark brown. Two uneven rows of yellowish-orange spots run from the top of the head (near the eyes) to the tip of the tail (dorso-lateral ranging).[9] The spotted salamander's spots near the top of its head are more orange, while the spots on the rest of its body are more yellow. The underside of the spotted salamander is slate gray and pink. Sexual dimorphism, physical differences between males and females, is displayed in the form of larger-bodied females having brighter-coloured spots.[10]
The scientific name Ambystoma maculatum comes from Ambystoma– amblys (Greek) for blunt; -stoma (Greek) meaning mouth; or anabystoma (New Latin) meaning ‘to cram into the mouth’ maculatum – macula (Latin) for spot; maculosus (Latin) for spotted.[11]
The spotted salamander usually lives in mature forests with ponds or ephemeral vernal pools for breeding sites.[12] Vernal pools are suitable breeding sites for these amphibians as they dry often enough to exclude fish that eat the salamander eggs and larvae, while retaining water long enough to allow amphibian larvae to complete development and metamorphose into terrestrial adults.[13] A study showed larger pools (as opposed to smaller pools) had more egg masses, higher occupancy, and higher larval survival rates for spotted salamanders.[14] Outside of the breeding season, these salamanders spend their time in forests with well-drained soils that contain many burrows dug by small mammals.[8]
Salamander populations from nearby pools form genetically-distinct metapopulations. Subpopulations within 4.8 kilometers share a higher proportion of genes, while populations greater than 4.8 kilometers share a smaller proportion of genes. Inter-population dispersal is likely mediated by both species-specific behaviors and natural limitations.[15]
Spotted salamanders are fossorial, meaning they spend most of their time underground. They rarely come above ground, except after a rain or for foraging and breeding. During the winter, they brumate underground, and are not seen again until breeding season in early March–May.[16]
Ambystoma maculatum has several methods of defense, including hiding in burrows or leaf litter, autotomy of the tail, and a toxic milky liquid it excretes when perturbed. This secretion comes from large poison glands around the back and neck. The spotted salamander, like other salamanders, shows great regenerative abilities: if a predator manages to dismember a part of a leg, tail, or even parts of the brain, head, or organs, the salamander can grow back a new one, although this takes a massive amount of energy.[17] As juveniles, they spend most of their time under the leaf litter near the bottom of the pools where their eggs were laid. The larvae tend to occupy refuges in vegetation, and lower their activity in the presence of predators.[18]
Ambystoma maculatum tend to follow the same path in their migration to and from their burrows and breeding pools.[19] They accomplish their journey in conditions that lack visual cues, since it is usually during periods of cloud cover. Some studies show evidence of landmark learning in spotted salamanders. Researchers found that spotted salamanders can associate visual landmarks with food. Thus spotted salamanders may learn landmarks in their habitat that are reliable indicators of resource locations or provide orientation clues for migration to and from breeding ponds.[20]
Spotted salamanders feed on earthworms, slugs, snails, spiders, millipedes, centipedes, insects, algae and other invertebrates.[21][22] They sometimes also feed on smaller salamanders, such as the red-backed salamander.[23] The adult spotted salamander uses its sticky tongue to catch food.[23]
During the majority of the year, spotted salamanders live in the shelter of leaves or burrows in deciduous forests. However, when the temperature rises and the moisture level is high, the salamanders make their abrupt migration towards their annual breeding ponds. Recent studies, however, indicate that temperature may be a more important factor than precipitation, as precipitation in winter months increase, yet salamanders do not migrate.[24] In just one night, hundreds to thousands of salamanders may make the trip to their ponds for mating.[16] Males will start a dance-like behavior called a liebsspiel, where afterward they lay down their spermatophore.[25] Males will migrate at higher rates than females early in the migration season. This could be due to different responses to temperature between males and females.[24] Mates usually breed in ponds when it is raining in the spring. Females usually lay about 100 eggs in one clutch that cling to the underwater plants and form egg masses.
The egg masses are round, jelly-like clumps that are usually 6.4–10.2 cm (2.5–4 in) long. The spotted salamander produces a unique polymorphism in the outer jelly layers of its egg masses: one morph has a clear appearance and contains a water-soluble protein, whereas the other morph is white and contains a crystalline hydrophobic protein.[26][27] This polymorphism is thought to confer advantages in vernal pools with varying dissolved nutrient levels, while also reducing mortality from feeding by wood frog larvae.[28][29]
Adults only stay in the water for a few days, then the eggs hatch in one to two months. When the eggs hatch depends on the water temperatures. Eggs of A. maculatum can have a symbiotic relationship with the green alga Oophila amblystomatis.[30] A dense gelatinous matrix surrounds the eggs and prevents the eggs from drying out, but it inhibits oxygen diffusion (required for embryo development).[31] The Oophila alga provides increased oxygen and supplemental nutrition from fixed carbon products via photosynthesis[32] and removes the embryo’s nitrogenous waste (ammonia) in the egg capsule, aiding in the salamander's embryonic development and growth.[33] The developing salamander thus metabolizes the oxygen, producing carbon dioxide (which then the alga consumes). Photosynthetic algae are present within the egg capsule of the developing salamander embryo, enhancing growth. However, the widely used herbicide, atrazine, has been found to significantly lower hatching success rate by eliminating the symbiotic algae associated with the egg masses.[34]
As larvae, they are usually light brown or greenish-yellow. They have small dark spots and are born with external gills. In two to four months, the larvae lose their gills, and become juvenile salamanders that leave the water. Spotted salamanders have been known to live up to 32 years,[35] and normally return to the same vernal pool every year. These pools are seasonal and will usually dry up during the late spring and stay dry until winter.
Spotted salamanders are often preyed on by raccoons, skunks, turtles, and snakes. For this reason they perform an important function by connecting the food chain.[8] Moreover, one of their predators is humans since they are popularly[36] sought out through the pet trade.
The spotted salamander or yellow-spotted salamander (Ambystoma maculatum) is a mole salamander common in eastern United States and Canada. It is the state amphibian of Ohio and South Carolina. The species ranges from Nova Scotia, to Lake Superior, to southern Georgia and Texas. Its embryos have been found to have symbiotic algae living in and around them, the only known example of vertebrate cells hosting an endosymbiont microbe (unless mitochondria are considered).
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