By Rachel Rossiter Smith, Metea County Park Naturalist
The Salamander has been around since the Mesozoic Era, when it broke off from other amphibians. Salamanders are the only amphibians that have long tails as adults. Many salamanders can shed their tails if a predator threatens them. Once shed, the tail reflexively flails about on the ground and distracts the would-be predator while the salamander slips away and later regenerates a new tail.
Like all amphibians, salamanders have delicate, permeable skin through which water and gases (such as oxygen and carbon dioxide) can enter and leave the body. Most adult salamanders have saclike lungs for breathing air and use their permeable skin only as a source of supplemental oxygen. Some species never develop lungs and instead obtain oxygen through gills or through their skin and the mucous membranes of their mouths and throats. This makes them very susceptible to environmental pollutants.
Many salamanders are nocturnal — that is, they do most of their hunting in the cool, dark hours of night and remain inactive during the day. Those that are active during daylight retreat to the cool depths of bushes and other ground cover during the hottest period of the day. Some groups are active only during certain seasons. When conditions are too cold or too dry for them to muster the energy necessary to find food, these salamanders enter a resting state similar to hibernation. For example, the siren spends much of its time burrowed in the muddy bottom of seasonal ponds and ditches that dry up in the heat of the summer; when the mud and sand starts to dry, the mucous coating on its skin hardens to form a protective cocoon, which enables the siren to survive out of water for many weeks.
The life cycle of salamanders varies greatly among species. Among most, fertilization occurs internally, meaning the egg and sperm unite inside the female’s body. During mating, salamanders use the cloaca, a chamber that opens into the animal’s digestive and urinary tracts as well as their reproductive tracts. All salamanders have a larval stage in which they have external, feathery gills for breathing in water. Among salamanders that lay their eggs on land, the larval stage occurs inside the egg. In salamanders that give birth to live young, the larval stage takes place within the body of the mother. Only some salamander larvae actually live in a body of water such as a pond or stream.
Many salamander larvae undergo a transformation called metamorphosis, in which their bodies change in ways that make them better suited to life on land than life in the water. During metamorphosis, the larvae of most species lose their gills and acquire a pair of saclike lungs. The heart transforms from the two-chambered heart needed to support gills to a three-chambered heart capable of supporting lungs. The larvae also grow limbs, eyelids, and well-developed tongues.
Unfortunately, people are the salamander’s worst enemy. Humans continue to pollute and destroy wetland habitats. Remember, these amphibians need water to survive. Filling in their ponds, using pesticides, and rerouting water for our own water needs has caused declines in many salamander populations. We need to help conserve remaining habitats and provide new gardens and parks for these unique creatures.