Salamanders and Newts of the United States
Approximately 350 salamander species are known from North and South America and the north temperate zones of Europre, Asia, and North Africa. They belong to 8 families, 7 of which are represented in North America. The sirens. mole salamanders, and amphiumas are found nowhere else. 112 species occur north of Mexico.
Secretive, typically nocturnal, and vioceless, salamanders are not nearly as familiar to us as their moist skinned relatives, the frogs and toads. Since they have slender bodies, long tails, distainct body regions, and usually possess front and hind legs of nearly equal size, salamanders are often mistaken for lizards. However, they lack the scaly skin, claws, and external ear openings which characterize the reptiles they superficially resemble. Adults, live their larvae, are carnivorous.
Salamanders display a wide range of courtship patterns. With the exception of the Hellbender and Asian species, fertilization is internal. It is accomplished without copulation. Spermotophores, gelantinous pyramidal structures which are capped with a packet of sperm, are deposited by the male. The female retrieves a sperm cap with her cloacal lips and the jelylike eggs are fertilizaed as they pass through the cloaca. Most salamanders lay their eggs in water. Those that do not do so select a sheltered, moist cavilty for eggs deposition. Larvae hatching into water bear external gills that are lost during transformation. The larvae of species that lay eggs on land bypass the aquatic stage and hatch as miniature replicas of the adults.
One Species found in North American
All giant salamanders are strictly aquatic. Fertilization is external. Gender is difficult to determine except during the breeding season when males develop a swollen ring around the cloaca and feamles a swollen abdomen.
Sirens are aquatic permanent larvae and are easily mistaken for eels as they have long bodies with external gills and gill slits, no hind limbs, and tiny forelegs. Sirens are primarily carnivorous and they forage at night for prey. When their watery habitat dries up, sirens aestivate in mud burrows. GLands in the skin secrete a mucus cocoon to protect their bodies from desiccation. Gender cannot be determined visually.
Six species are found in North America. Notophthalmus, the eastern newts inhabit eastern North America, and Taricha, the western newts, are found along the Pacific coast.
The skin of newts is not slimy but rough textured unlike that if other salamanders and the coastal grooves are indistinct.
As the breeding season approaches, male newts develop swollen vents, broadly keeled tails, and enlarged hind legs with black, horny structures on the inner surface of the thighs and toe tips. In male western newts, the skin becomes smooth.
Eastern newts are primarily aquatic, while western newts are terrestrial. Transforming eastern newts leave the water as brightly colored forms called efts that live on the forest floor for 1 to 3 years and then return to the water to assume adult characteristics. Occasionally the larvae change directly into adults, skipping the eft stage. Western newts, by contrast, do not undergo an eft stage. They hatch as aquatic larvae, tehn transform into land dwelling adults that return to the water at breeding time.
Two genera, Necturus, the mudpuppies and waterdogs, with 5 species in eastern North America, and 1 species of Proteus, a blind cave dweller in Europe. Mudpuppies and waterdogs are aquatic permanent larvae, characterized by deep red plume like gills, 4 toes on both front feet and hind feet, and strongly compressed tails. The male's vent is lined with tiny projectdions, bears 2 fleshy lobes, and is followed by a tranverse broove.
Fertilization is internal and the eggs are laid on the undersides of stones or logs on stream bottoms. The female guards the eggs until hatching.
The smallest family of salamanders with only 1 genus, Amphiuma, with 3 aquatic species restricted to the southeastern United States. Amphiumas are eel like and bear 4 useless tiny limbs, each with 1 to 3 toes. Larvae hatch with external gills and do not transform completely. Adults loose gills but retain one pair of gill slits. Amphiumas are primarily nocturnal and carnivorous. Courtship takes place in the water and fertilization is internal. The female lays a long beadlike string of eggs in a muddy depression in shallow water and guards them until they hatch.
3 Genera: Ambystoma, Dicamptodon, and Rhyacotriton. All occur in North America, from southeastrn Alaska and Labrado to the southern edge of the Mexican Plateau there are 18 species in our range.
Adult mole salamanders are cahracterized by robust bodies and limbs and short blunt heads. ack of a nasolabial groove between lip and nostrils distinguishes moles from lungless salamanders. During the bredding season males develop a swelling around the vent. Larvae have wide heads with ling plume like gills and well developed tail fins. Larvae of some species do not transform but breed in larvae form.
Courtship and breeding usually take place in ponds in late wiunter or early spring. Fertilization is internal. Adult mole salamanders are typically terrestrial and confirmed burrowers. Both larvae and adults are carnivorous.
The largest family of salamanders, it is believed to have originated in eastern North America. There are 23 genera and about 215 species, 80 of which occur in North America.
Species of the genera Plethodon and Batrachoseps are long and slender, while Pseudotriton and Desmognathus are robust. All are lumgless and breathe through their thin moist skin. All have a nasolabial groove, a small narrow gland lined slit between the nostril and upper lip. Costal grooves are well defined. Most are terrestrial species that lay eggs on land. Others are fully aquatic, partly aquatic, or completely terrestrial.
Lungless salamanders conduct an elaborate courtship. Males rub and prod females, and females may straddle the male's tail while he moves forward and drops a spermatophore for her to retrieve. Males have a mental gland under the chin, and, during breeding season the area surrounding their vent is greatly enlarged. Fertilization is internal. Females often coil about and guard egg clutch durng its development, with hatchlings appearing as miniature replicas of adults.