365 Urban Species. #296: Northern Dusky Salamander

Photos by cottonmanifesto. Momentarily captured in a hat, to be shown to the members of the Urban Nature Walk group.

Urban species #296: Northern dusky salamander Desmognathus fuscus

Bullfrogs not withstanding, amphibians are not commonly found in urban areas. The reason is their semi-aquatic habits, and their permeable skin. Water and gases can pass through an amphibian's skin, and so if the water or air are polluted, that pollution can enter the animal's bloodstream. Most urban water contains too many metals and other contaminants to support amphibian life. Even those amphibians that live on land lay their eggs in water, or in moist earth, exposing their developing young to environmental poisons. While permeable skin may seem like a complete liability, it has its advantages. Because oxygen and carbon dioxide can pass directly through an amphibian's skin, they have reduced the need for lungs. In a few species, such as the northern dusky salamander, and the exceedingly common redback salamander, the lungs have completely disappeared. The lungless condition is thought to have evolved to reduce buoyancy in stream-dwelling salamanders, and has persisted in several descendant species that live in other habitats.

The small colony of northern dusky salamanders I discovered lives on the margin of Ward's pond in Olmsted Park. Jamaica pond is uphill and upstream from Ward's pond, and water from Jamaica pond seeps through the soil between the ponds. This water, originating in a natural spring, is relatively clean, and very cold. Forested groundwater seeps are the preferred habitat of this species, and it is through the fortuitous creation of Olmsted Park that this population of salamanders survives in the city. They hide under fallen wood, feeding on small invertebrates, writhing when disturbed, with the help of a keeled tail, even taking to the water when pressed. They don't generally enter the pond itself, where they would be quickly preyed upon by turtles and fish.

Urban manatee!

Thanks to bellelvsbeast

Manatee in memphis