Salamanders – with their smooth skin, little heads, big eyes and long tails, where in the world of taxonomy do they belong? Are they a cuter version of lizards? Snakes with legs? Elongated frogs? How about attractively-evolved worms? Nope: salamanders, and their rougher skinned cousins, the newts, belong to the order, Caudata. Caudata essentially means “amphibian with a tail”, so of the above possibilities, salamanders fall taxonomically closest to frogs, their tailless amphibious cousins.
Some of you may be wondering why, at this frigid time of year, I am writing about creatures seldom seen in even the warmest months of summer. True, salamanders are inordinately shy little guys. Most spend their days hiding under moist logs or rocks, venturing out only in the cover of darkness to hunt down their prey. Themselves food to various fish, snakes and birds, their nocturnal lifestyle helps the lowly salamander to stay out of harm’s way.
But in this winter of winters, how do these little ectotherms make it? We survive in parkas, heated homes and by keeping a warm cup of coffee ever in view. So what do these essentially naked little creatures, dependent on the environment for warmth, do to survive the winter? Hibernation is the key, and I must admit that I too see the logic in such behaviour on these dark winter mornings. Burying themselves deep underground to avoid frost and maintain the ambient moisture levels so essential to their survival, salamanders wait out the cold.
Spring (ahh, spring) is another story. As many of us would like to do at that first sign of the sun’s returning power, salamanders and newts pick up their heads, do a little stretch, and head out for the beach. It is here, in the ponds and waterways of the world, that salamanders know spring love. Breeding ponds are the Mecca of salamanders, and migration from all directions centres on the nearest patch of agua fresca. Migration? I know, the term is generally reserved for the more highly esteemed members of the animal kingdom, including caribou, ducks and butterflies. But this widespread movement across the landscape, even by such miniature creatures, warrants the title of migration nonetheless.
For salamanders, as for all romantics, seeking true love can be a deadly business. While acid rain, polluted waterways and habitat loss (where is that pond, anyway?) rank high on the list of factors contributing to salamander decline, the animal’s passionate journey to the waters of romance leave many a casualty along the way. By the hundreds, salamanders march their way across the landscape, through forests and marshes and, just when the pond comes in sight, they march right on across the road. And by the hundreds, these delicate amphibians meet their maker, like their larger animal brethren the deer, moose or family pet, at the hands of motorists.
So therein lies the danger of salamander love. But what about those who make it? Well, it varies depending on what type of salamander we’re talking about. We in North America are lucky to have the greatest diversity of salamanders in the world: representatives of nine of the ten families of salamanders are found here, in our moist woods and extensive waterways. Of the 360 species known worldwide, most in our region are small (less than 15 cm long). We are not graced with the bulk of Andrias japonicus, the world’s largest salamander (1.5m in length!). But we do have an incredible variety of salamanders, ranging from entirely aquatic, to entirely terrestrial varieties, to those with the more common biphasic life cycle (i.e. metamorphosis from a gilled aquatic to a lunged terrestrial form).
Nevertheless, regardless of size, type or family history, for all to go well on arrival, the water has to be just right. As reliant on their skin’s vascular network as they are on lungs or gills to breathe, salamanders of all kinds require clean, pure water within a restricted pH range. The specific environmental requirements of salamanders and other amphibians make them excellent indicator species. Because of the large degree of exchange that occurs through their skin, salamanders, like all amphibians, are especially vulnerable to external environmental changes. Therefore, the health and population trends of these species indicate to scientists changes that may be occurring in the environment, changes in factors such as pH, water chemistry or temperature variations.
For those who find their water source just so, breeding can at last occur. For most types of salamanders, fertilization is internal: the female picks up the male’s previously-deposited spermatophore (sperm sack), fertilization takes place, and soon enough the aquatic young are released to their new watery home.
Ponds in which the young first find themselves are often temporary bodies of water. With the onset of warm weather, water levels frequently begin to decrease and these gilled larvae go through the process of metamorphosis in which, among other things, the young develop lungs and legs. With their new equipment, specially designed for life on land, young salamanders leave the nest and set off to make their way in the world. On finding a snug log to call home, and a territory filled with soft, moist ground and plenty of smaller creatures to call dinner, the fledgling salamander will grow, mature, and prepare itself for the journeys its parents took a generation’s cycle earlier.
For more information on salamanders, their life cycle and environmental threats, have a look at the following websites, as well as any introductory herpetology or biology textbooks:
http://museum.gov.ns.ca/mnh/nature/salamand
http://tolweb.org/tree/eukaryotes/animals/chordata/caudata/caudata.html
http://home.total.net/~kaymur/
http://www.chl.ca/AllAboutCanoesNewsJun01/20_sala-sun.html
Zoe Dalton is a graduate of York University’s environmental science program, and is currently enjoying working towards a Master of Arts in Integrated Studies with Athabasca U. She can be reached for comments or questions at zk_dalton@hotmail.com
