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Aug 1, 2017 11:46 AMPublication: The East Hampton Press & The Southampton Press

The Mysterious Newt

Terrestrial forms of the Eastern newt found on Long Island. The brilliant-colored red eft stage has been reported but is very rare on Long Island. JOE JANNSEN
Aug 1, 2017 11:46 AM

The recently published book titled “The Amphibians and Reptiles of New York State” states that the eastern newt (Notophthalmus viridescens) is probably our most familiar salamander among the general public. Unlike our mole salamanders—the spotted, marbled, blue-spotted and tiger—that are largely fossorial and only emerge from their underground haunts for a brief breeding period, or the ubiquitous redback salamander that is most active hunting prey at night, hunkering down in the leaf litter and beneath decaying logs by day, the newt is diurnal and our most visible salamander during the day.It also has the most complex life cycle of any of our native salamanders in the state, including a juvenile terrestrial stage that is so different in appearance from the adults that it is given an entirely different common name: the red eft.

Measuring 1 to 4 inches in length and sporting a brilliant orange-colored skin embedded with small red dots that are encircled in black, it is hard not to spot even the smaller-sized red efts, and it is this form of the newt that many of us first encounter in the wild.

My first encounters were as a child on vacation for a week or two in the Adirondacks. On cool, humid mornings in August following a rainy night we would search the woods adjacent to the cabin where dozens of red efts could be found moving slowly atop the leaves and moss hunting for insects, earthworms, mites and other tiny invertebrates.

In addition to their striking color, they can be astonishingly plentiful. Tom Tyning, author of one of the Stokes Nature Guides titled, “A Guide to Reptiles and Amphibians,” reports counting 523 red efts along a one-mile stretch of abandoned road adjacent to a mixed forest of maples, cherries and hemlock. That’s approximately one per 10 feet of roadside!

The Eastern newt has a very long breeding season that commences in spring and continues at least through the summer months. Two hundred to 400 eggs are laid individually on the stems and leaves of aquatic vegetation to which they adhere over their three to five week incubation period, the variable time being related to water temperature. The tiny eggs are very difficult to find.

At hatching, the larvae are slightly less than a half-inch long, yellow-green colored with a grayish stripe along the sides and branched, external gills. They sink to the bottom of the pond and are inactive for several days. Within a week they are feeding on microcrustaceans such as water fleas or daphnia, and insect larvae including that of mosquitoes, and over the course of their three-month long larval stage they grow to one and a half inches long.

In autumn the larvae metamorphose into their juvenile terrestrial form that has its own distinct name: the red eft. Physical changes include reabsorbing their gills and tail fins, developing lungs and a rough-textured, brilliantly-colored, thick skin that fills with poison glands, and altering their feeding structure from one relying on sucking up water prey to one utilizing a long tongue to capture crawling prey.

The brightly colored, very conspicuous and poorly camouflaged red eft, as with the monarch butterfly larva and adult, relies on its high visibility as a warning to potential predators that “toxins are aboard: eat me at your own risk.” The poison is tetrodotoxin, the same class toxin that is found in the puffer fish. The terrestrial juveniles are ten times more toxic than the aquatic adults. Perhaps this is the reason newts are a common ingredient in witches’ stews.

Red efts roam about the forest floor for two to five years and act as a dispersal stage for this species, enabling them to quickly colonize newly formed ponds created by beaver. In fact, the eft stage may have evolved in response to the beaver’s habit of creating new ponds and abandoning old ones in woodland habitats.

The transformation into aquatic adults involves a second major metamorphosis during which they develop thinner, less toxic and more camouflaged skin that can absorb dissolved oxygen through the skin pores, regrow tail fins, and redevelop the suction-based feeding system.

Eastern newt adults measure four inches in length from nose to tip of tail and are an olive-dark green color above and yellowish below. Their topsides retain the small red dots that are encircled with black, giving rise to their other common name: the red-spotted newt. They are found inhabiting most types of permanent freshwater ponds, lakes and slow moving rivers that have abundant cover in the form of aquatic vegetation and are surrounded by at least 70 percent forest cover. The latter is important for the red eft stage. Studies have found that this species is very vulnerable to habitat fragmentation that particularly impacts the terrestrial stage of its life cycle.

Adult newts are somewhat active throughout the winter, even under the ice. Their main predator is the amphibian blood leech, a creature that avoids the toxic glands embedded in the skin by being able to pierce through the skin and feed directly on the tissues beneath.

Most adults live the rest of their lives, as many as 15 years, in their breeding ponds. But there are two notable variations to this life cycle, and neither appears to be well understood.

One variation is skipping the terrestrial eft stage altogether, and transforming directly from an aquatic larva to a gilled sub-adult. This is thought to be the rule here on Long Island, where there are extremely few records of red efts. Steve Biasetti found one in Vineyard Field, Bridgehampton on a very warm December Christmas bird count some years ago. And there is a report, and photo, of a red eft found at Mashomack Preserve, Shelter Island.

Another variation involves the adults leaving their pond in some summers, overwintering on land, and returning to the pond in spring. These terrestrial creatures do not move very far from their breeding pond, so their function is much different from the “wandering” efts in that they are not colonizing new areas. And it is not clear if these terrestrial forms are physically similar to the juvenile efts, nor what prompts the aquatic adults to undergo a third metamorphose for such a relatively short duration.

This also appears to be a common characteristic of newts here on Long Island, in that the vast majority of our terrestrial forms are found in close proximity to breeding ponds, the newts are dark olive green in color, and they are assumed to be a terrestrial form of the adult.

A phone call to one of the leading herpetologists in New York, Al Breisch, did not shed any light on this aspect of the newt’s natural history. Neither of these two variations is well understood and both remain a mystery even among the experts.

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