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Eurycea wilderaeBlue Ridge Two-lined Salamander

By Tanvi Khanpara

Geographic Range

Eurycea wilderae is predominantly found in the Nearctic region. Its range includes the Blue Ridge mountains, Cumberland mountains, and the Cumberland Plateau. It is one of the most common salamanders of the Great Smokey Mountains. They are found in the United States in the states of North and South Carolina, Georgia, Tennessee, and Virginia. (Jacobs, 1987; King, 1939; Sever, 1989)

Habitat

Adult Eurycea wilderae can be found in either forest (terrestrial) or streams (aquatic) depending on the time of year and whether they are mating. Usually they prefer the undersides of logs and other slightly damp locations when on land, but return to streams for mating. In the late winter, both males and females are found in streams, usually under rocks or logs, where they will mate and the female will lay her eggs. Blue Ridge two-lined salamanders require streams with suitable, submerged substrate (rocks) to oviposit under. Outside of the breeding season, many adults search out terrestrial burrows, undersides of logs, or other cover objects.

All juvenile Eurycea wilderae spend at least one year in a stream for development. Thus, juveniles are found in or near streams, generally under rocks, logs, or leaf litter.

This species selects habitats at an average 1,200 meters above sea level. (Bruce, 1986; Wiltenmuth, 1997)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • Average elevation
    1,200 m
    ft

Physical Description

Eurycea wilderae are lungless salamanders and therefore have nasolabial grooves below each nostril. Most individuals feature fleshy extensions of the upper lip that encompass these nasolabial grooves, also known as cirri.

Eurycea wilderae have two very distinct male sexual morphologies: morph wilderae males and morph A males. These two morphologies differ in their mental hedonic (lower jaw) glands, premaxillary teeth, cirria, and temporal musculature. The male wilderae have a mental hedonic gland, seasonally larger premaxillary teeth, cirri, and smaller temporal musculature, while the morph A lacks many of these characteristics and has larger temporal musculature. They do not have different habitats and they do appear very similar in appearance.

These slender salamanders range in length from 7 to 10.7 cm with a tail that makes up 55 to 60% of this total length. They are bright yellow-orange in color with two dorsolateral stripes running down the back. Between the two dorsolateral stripes, the dorsal area features many small, black spots from nose to tail. The sides are mottled with significant amounts of irregular, black spots as well. The number of costal grooves varies by elevation; populations below 1,200 meters feature 14, whereas populations above feature 15 or 16 grooves.

Eurycea wilderae was originally thought to be a subspecies of the larger Eurycea bislineata, but is now recognized as its own species. Eurycea wilderae is brighter in color (yellow to orange) than the browner Eurycea cirrigea and other relatives with long striped tails. (Bernardo and Reagan-Wallin, 2002; Bruce, 1986; Camp, et al., 2000)

  • Sexual Dimorphism
  • sexes alike
  • sexes shaped differently
  • Range length
    7 to 10.7 cm
    2.76 to 4.21 in

Development

Eggs are placed on the underside of stream logs or in other wet depositories. After approximately 1 to 2 years, in the late spring or early summer, larvae undergo metamorphosis. This time varies according to water temperature and type of stream. Larvae of these salamanders are yellow with a dorso-lateral stripe that is dashed and contains 3 rows of unpigmented lateral line spots.

After metamorphosis, juveniles usually remain in streamside habitats for some time before they spawn. They are usually found in streams or around them for the following 3 to 4 years before they are fully sexually mature, but there have been instances where they are mature by 2 years.

First year larvae usually go downstream and adults who are ready to spawn move upstream to do so.

Sex of these species, can be determined by the cirri as well as swollen, mental hedonic glands which are located under the lower jaw. During the breeding season, some males exhibit broad heads from these swollen glands. There are two morphs in males and one female morph that can breed with either of the two male morphs. (Bruce, 1986; Bruce, 1988; Ryan, 1998; Voss, 1993)

Reproduction

Courtship in Blue Ridge two-lined salamanders is not well documented. The presence of nasolabial grooves, which are lined with glands, and mental hedonic glands suggests that pheromones play a role in reproduction.

Eurycea wilderae gather at mating sites from October through April.

There may be a correlation between having premaxillary teeth and hedonic mental and tail glands in courtship. Enlarged premaxillary teeth may be correlated with a mental hedonic gland where the teeth scrape the female's skin allowing the male's mental hedonic gland to secrete a substance that can easily enter the female's circulatory system. (Jacobs, 1987; Sever, 1989)

Eggs are laid anywhere from early in the year to mid summer depending on the elevation. Clutch size may vary between populations, as some populations have been found to lay 8 to 34 while others lay 28 to 56. Clutches as large as 87 eggs have been reported, but this is likely a mass laid by several females.

After the eggs are fertilized, the larvae undergo metamorphosis after one to two years. Eurycea wilderae larvae usually eat invertebrates and are considered top predators in many of their habitats, but are preyed on by two other salamander species. The larvae length ranges from 11 to 18 mm, with an average of 16.7 mm.

After this metamorphosis, the juveniles live in streams and reach sexual maturity at 3 to 4 years of age. (Beachy, 1994; Bruce, 1986; Bruce, 1988; Ryan, 1998)

  • Breeding interval
    Eurycea wilderae breeds once yearly.
  • Breeding season
    Eurycea wilderae breeds from February to July.
  • Range number of offspring
    8 to 56
  • Range age at sexual or reproductive maturity (female)
    2 to 4 years
  • Average age at sexual or reproductive maturity (female)
    3 to 4 years
  • Range age at sexual or reproductive maturity (male)
    2 to 4 years
  • Average age at sexual or reproductive maturity (male)
    3 to 4 years

As far as is documented in any scientific literature, some mothers stay to guard their eggs but no additional information exists. (Voss, 1993)

  • Parental Investment
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

the average lifespan of Eurycea wilderae is estimated at 4.4 years, but few individuals live longer than 5 years and none have been documented older than 10 years. Factors that affect survival are poorly understood. (Bruce, 1988)

  • Range lifespan
    Status: wild
    4 to 10 years
  • Average lifespan
    Status: wild
    4.4 years

Behavior

As with most salamanders, Eurycea wilderae has competition based on size where larger individuals dominate over the smaller in courtship and habitat. There is little known about the social systems and competition involved in stream-dwelling salamanders, but what is known is that the larvae in these streams most likely interact and compete based on size. It may also be possible that larvae activity and behavior will be affected by the competition in the ecosystems. It is implied that the Eurycea wilderae have a hierarchy based off of size.

Though activity has been observed during the day, these salamanders are most active and do much of their feeding at night. Significant migrations have not been documented for this species. They have been noted to make small movements within streams and adults perform small movements from terrestrial to aquatic habitats during the breeding season. (Wiltenmuth, 1997)

Home Range

There is no information regarding territories for this species.

Communication and Perception

Some of the senses that are highly developed in Eurycea wilderae are used to help them distinguish between mating with their own species versus southern two-lined salamanders. The mating process involves tactile as well as chemical simulation. Eurycea wilderae, unlike the other related salamanders, does not partake in visual stimulation by fluttering movements of the forelimbs.

Information on how Eurycea wilderae perceives the environment is not well documented, but they likely perceive visual, tactile, and chemical stimuli. (Kozak, 2003)

Food Habits

Larval Eurycea wilderae usually feed at night on various aquatic invertebrates. These invertebrates feed on detritus and therefore limiting detritus does affect the food availability for Eurycea wilderae. The invertebrates they eat include copepods, cladocerans, chironomids, nematodes, and terrestrial insects. Adults in this species eat more terrestrial organisms, but specifics have not been studied. (Johnson and Wallace, 2005)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • terrestrial worms
  • other marine invertebrates

Predation

Eurycea wilderae larvae are preyed upon by spring salamanders and black-bellied salamanders. Common garter snakes prey on both larvae and adults.

Eurycea wilderae does, however, have the ability to sense a predator's arrival or can detect a harmed Eurycea wilderae through chemical sensing. Their cryptic dorsal mottling likely aids in camouflage within leaf litter and streams. (Beachy, 1994; Marvin, et al., 2004)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Eurycea wilderae belongs in a detritus-based ecosystem. They are limited by detritus because the marine invertebrates that they eat consume detritus. Furthermore, Eurycea wilderae serves as prey for two other salamanders, Gyrinophilus porphyriticus and Desmognathus quadramaculatus.

There are no known host species of this species. Eurycea cirrigea, a closely related species, is used as a keystone species where they cycle nutrients in forest communities. However, this is speculative and may not be accurate for Eurycea wilderae. (Beachy, 1994; Johnson and Wallace, 2005)

Economic Importance for Humans: Positive

Eurycea wilderae does not provide any economic importance for humans.

Economic Importance for Humans: Negative

There are no known negative effects of Eurycea wilderae on humans.

Conservation Status

Eurycea wilderae is not currently considered a threatened species, and the IUCN Red List considers this species to be of least concern. However, pollution, deforestation and other human threats to their aquatic and terrestrial habitats could affect populations.

Contributors

Tanvi Khanpara (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, Rachelle Sterling (editor), Special Projects.

Glossary

Nearctic

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.

World Map

bilateral symmetry

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. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

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).

metamorphosis

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.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

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).

terrestrial

Living on the ground.

visual

uses sight to communicate

References

Beachy, C. 1994. Community Ecology in Streams: Effects of Two Species of Predatory Salamanders on a Prey. Herpetologica, 50/2: 129-136. Accessed March 14, 2010 at http://www.jstor.org/stable/pdfplus/3893019.pdf.

Bernardo, J., N. Reagan-Wallin. 2002. Plethodontid Salamanders Do Not Conform to "General Rules" for Ectotherm Life Histories: Insights from Allocation Models about Why Simple Models Do Not Make Accurate Predictions. Oikos, 97/3: 398-415. Accessed March 20, 2010 at http://www.jstor.org/pss/3547661.

Bruce, R. 1986. Upstream and Downstream Movements of Eurycea bislineata and Other Salamanders in a Southern Appalachian Stream. Herpetologica, 42/2: 149-155. Accessed March 20, 2010 at http://www.jstor.org.proxy.lib.umich.edu/stable/3892380?seq=1.

Bruce, R. 1988. An Ecological Life Table for the Salamander Eurycea wilderae. Copeia, 1988/1: 15-26. Accessed February 21, 2010 at http://www.jstor.org/stable/1445917.

Camp, C., J. Marshall, K. Landau, R. Austin Jr, S. Tilley. 2000. Sympatric Occurrence of Two Species of the Two-Lined Salamander (Eurycea bislineata) Complex. Copeia, 2000/2: 572-578. Accessed March 10, 2010 at http://www.jstor.org/stable/1448209?seq=2.

Jacobs, J. 1987. A preliminary investigation of geographic genetic variation and systematics of the two-lined salamander, Eurycea bislineata (Green). Herpetologica, 43: 423-446.

Johnson, B., J. Wallace. 2005. Bottom-up limitation of a stream salamander in a detritus-based food web. CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES, 62/2: 301-311. Accessed March 15, 2010 at http://apps.isiknowledge.com/full_record.do?product=WOS&search_mode=GeneralSearch&qid=6&SID=1CPg54BPCieiAFBC3L@&page=1&doc=1.

King, W. 1939. A Survey of the Herpetology of Great Smoky Mountains National Park. American Midland Naturalist,, 21/3: 531-582. Accessed March 15, 2010 at http://www.jstor.org/stable/2420516?seq=52.

Kozak, K. 2003. SEXUAL ISOLATION AND COURTSHIP BEHAVIOR IN SALAMANDERS OF THE EURYCEA BISLINEATA SPECIES COMPLEX, WITH COMMENTS ON THE EVOLUTION OF THE MENTAL GLAND AND PHEROMONE DELIVERY BEHAVIOR IN THE PLETHODONTIDAE. SOUTHEASTERN NATURALIST, 2/2: 281-292.

Marvin, G., R. Whitekiller, V. Hutchison. 2004. Avoidance of Alarm Chemicals by Plethodontid Salamanders (Genus Eurycea): Importance of. Herpetologica, 60/1: 24-33. Accessed March 16, 2010 at http://www.jstor.org/stable/pdfplus/3893568.pdf.

Ryan, T. 1998. Larval Life History and Abundance of a Rare Salamander, Eurycea junaluska. Journal of Herpetology, 32/1: 10-17. Accessed April 19, 2010 at http://www.jstor.org/pss/1565473.

Sever, D. 1989. Caudal Hedonic Glands in Salamanders of the Eurycea bislineata Complex (Amphibia: Plethodontidae). Herpetologica, 45/3: 322-329. Accessed March 20, 2010 at http://www.jstor.org.proxy.lib.umich.edu/stable/3892888?seq=5.

Sever, D. 1979. Male Secondary Sexual Characters of the Eurycea bislineata (Amphibia, Urodela, Plethodontidae) Complex in the Souther Appalachian Mountains. Journal of Herpetology, 13/3: 245-253. Accessed March 15, 2010 at http://www.jstor.org/stable/info/1563315?seq=1.

Voss, S. 1993. Relationship between Stream Order and Length of Larval Period in the Salamander Eurycea wilderae. Copeia, 1993/3: 736-742. Accessed February 21, 2010 at http://www.jstor.org/stable/1447235.

Wiltenmuth, E. 1997. Agonistic Behavior and Use of Cover by Stream-Dwelling Larval Salamanders (Eurycea wilderae). Copeia, 1997/2: 439-443. Accessed February 15, 2010 at http://www.jstor.org.proxy.lib.umich.edu/sici?sici=0045-8511(199705)%3A2%3C439%3AABAUOC%3E2.0.CO%3B2-A&origin=ISI&cookieSet=1.

Wood, J. 1949. Eurycea bislineata wilderae Dunn. Herpetologica, 5/3: 61-62. Accessed March 15, 2010 at http://www.jstor.org/stable/3890169.

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