Salamander Species, Taxonomy, and Ecology
Taxonomy
Salamanders are amphibians from the order Caudata, class Amphibia, phylum Chordata, that are distinguishable from other amphibians by having a tail present in all stages of life along with limbs set at right angles to their body. They also have some other, more complex, features that distinguish them from other amphibians such as: the presence of ribs, having true teeth on both jaws, and the absence of an otic notch and middle ear. They inhabit almost all northern temperate regions, where there are cool and moist habitats. Salamanders have a biphasic life cycle. Most species have an aquatic larvae form that has external gills which grows and metamorphizes into an adult terrestrial form that breathes either through lungs that develop or through its moist skin. Some species lack metamorphosis and stay in the larval appearance living in water while others hatch on land and stay in terrestrial forms that resemble small adults. They are carnivorous in all stages of their life cycle and prey mainly on small arthropods [2]. Salamanders migrate yearly to vernal pools to breed but it is entirely weather dependent.
Migrations
There is a myth of the big night, that after a long, snowy, cold winter, spring comes and it starts to rain and then all on one night the amphibians come out of their burrows and migrate to vernal pools to lay their eggs. While this myth is partially true, it does not happen all on one night, the weather conditions have to be just right. Three things are needed for the migrations to happen. There needs to be thawed ground with minimal snow cover. It also needs to be warm, at least above 40 degrees, but 45 degrees is the prime low temperature for the migrations to happen. Lastly, it needs to be raining or if there is a drought it has be humid and foggy.
Vernal pools are woodland wetlands that form in depressions in the forest floor from snow melt and rainfall. They start to shrink and dry up from evaporation as the temperature begins to warm and the seasons change so by summer the pool is gone. Since they are only temporary pools, fish cannot live there to feed on the eggs and larvae which make it a suitable place to lay their eggs. Salamanders typically go back to the same site every year again and again, usually the one that they were originally born at. What happens at the vernal pools is that typically the males arrive first and congress with one another, once a female arrives a male will go up to her and rub chins ‘dancing’ to see if they like one another. If she approves she will sit on his spermatophores to fertilize her eggs before laying them on a branch of a twig or a pile of leaves. The eggs then take 6-8 weeks to hatch but those who survive can live twenty to thirty years. Even though there are no fish, the vernal pools still serve as “fast food oasis’s” for other spring wildlife in New England such as birds.
New Hampshire Salamanders
New Hampshire has 12 species of salamanders state wide that live in a range of habitats from rivers, forests, marshes, and vernal pools but, they are hard to get an accurate survey on the population as they spend most of their time underground. The Northern redback salamander is the most abundant salamander in New Hampshire. It completes its entire life cycle on land acting as both predator and prey to other organisms. The state amphibian is the red eft, referring to the juvenile form of the Eastern newt. The red eft is brightly colored to warn predators of its toxicity and as they transition into adults they turn into an olive color and develop a fin on the top of their tail. The juveniles spend up to three years on land but the adults tend to spend their lives in the water. A study done by Burton and Likens in 1975 at Hubbard Brook Experimental Forest found that the combined weight of all the red-backed salamanders they found equaled that of all the small mammals they found and was twice the weight of all the birds documented [1].
Mole Salamanders
Mole salamanders are the group of salamanders that are primarily associated with the season wetlands of vernal pools. They spend a majority of the year underground in the forests surrounding the pools. The most common mole salamander is the spotted salamander which is distinguishable by its bright yellow spots on its black back. Spotted salamanders are 6-8 inches long and also have a smile on their face. The Jefferson salamander and the blue spotted salamander are less common. It is difficult to get an accurate count on their abundance because they interbred creating a hybrid where genetics is the only way to confirm for certain which species is which. The rarest mole salamander is the marbled salamander which is listed as endangered. It is a thick bodied salamander that is dark in color with grey bands of various shapes and patterns on its back. Instead of laying their eggs in the spring, this species lays them in the fall. Larvae spend the winter under ice so they are larger than the other amphibians larvae that hatch in the spring [1]. There are a lot of threats and conservation challenges for salamanders.
Threats to Salamanders Ecology
The biggest threat to mole salamanders is the loss and fragmentation of its habitat. Vernal pools are being filled for the development of humans and the surround forest land is being deforested. Since the species spend most of their lives underground in their burrows there is not sufficient data to accurately assess the status of their populations. Salamanders are also a challenging animal to conserve because of emerging diseases. Entire populations can be wiped out by the introduction of a new disease but, they are considered to be indicator species meaning that if salamanders are around then it is a good indicator that the environment there is healthy [1]. They also help reduce the amount of carbon that is released as greenhouse gases. This is done by eating insects and other invertebrates that eat leaf litter on the forest floor helping to make the carbon released go into the soil compared to the atmosphere. This shows just how important it is for these small organisms to be better surveyed to know their conservation status and if they need to be better protected.
Salamanders also have a large ecological role in the ecosystem. They help to regulate food webs and contribute to the ecosystems stability in several ways stated by Robert D. Davic and Hartwell H. Welsh Jr. in their paper “On the Ecological Roles of Salamanders.” They state that salamanders provide both direct and indirect biotic control of species diversity and ecosystem processes through grazer and detritus pathways from being a mid-level vertebrate predator. Through migrating, the salamanders connect energy and matter between the aquatic and terrestrial ecosystems they inhabit and contribute to soil dynamics from their underground burrow systems. Also, they supply high-quality storages of energy and nutrients to tertiary consumers as the ecosystem gradually changes over time [3]. Salamanders have been able to withstand these changing conditions of habitats through the past 150-200 million years.
The different environments inhabited by salamanders have been varied through droughts, floods, human interferences, dams, and climate change. The salamanders have been able to sustain themselves with more than 400 species in 59 different genera and 10 families but their habitats are increasingly being harmed. Almost three-fourths of forested ecosystems in North America are considered to be endangered due to environmental and human made threats. The cost of this is unknown. The decline of amphibian species and salamander populations are declining with unknown consequences to the ecosystems natural processes [3]. It is important for us to better understand how salamanders affect the ecosystem as the climate continues to change and human impact the environment.
Works Cited
[1] Keating, Allison. “Salamanders of New Hampshire.” Wildlife Journal, Apr. 2015, wildlife.state.nh.us/pubs/documents/samples/wj-b15-salamanders.pdf.
[2] Larson, Allan, et al. “Caudata.” Caudata, 3 Jan. 1996, tolweb.org/Caudata.
[3] Davic, Robert D., and Hartwell H. Welsh. On the Ecological Role of Salamanders. 26 July 2004, www.fs.fed.us/psw/publications/welsh/captured/psw_2004_welsh008.pdf.
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