PHOTO COURTESY OF GARRY KESSLER
Don’t eat me! This red eft is a juvenile red-spotted newt that lives on land. Its bright red-orange color warns off predators. Its skin is poisonous to animals that eat it, but not to the human touch. The red-spotted newt gets its name from the small red spots ringed with black on its back. Both the red eft and the dull-colored adult newt have the spots.
August 29, 2008, Page 11
By Annie Reid
Westborough Community Land Trust
A surprising salamander
A bright red-orange salamander, resting boldly out in the open in broad daylight, can be a surprising sight in late August or early September near one of Westborough’s many streams or ponds.
What is this fearless creature that sees no need to hide under rocks and logs or travel under cover of darkness, as other salamanders do?
It’s a red eft, which is a life-stage of the red-spotted newt (Notophthalmus viridescens viridescens). Newts are a type of salamander. The red eft lives on land, and it’s a wandering, juvenile stage. Aha, you might think, even salamanders have teenagers who throw caution to the winds . . .
But what’s with the bright color? Is the red eft supposed to be hiding among autumn leaves?
The startling red-orange color is indeed protection for the red eft. But it doesn’t work by helping the red eft blend in with its surroundings, even if autumn is on the way. Instead, it makes the red eft stand out in the environment. The color says, watch out!
On many creatures, reds and oranges are nature’s stop signs. These warning colors tell other animals to keep away. Predators who might be tempted to eat the colorful creatures seem to get the point. Typical predators of salamanders, such as birds and snakes, usually pass up the chance to dine on a red eft.
What could be so dangerous about a little salamander, only 3-5 inches long? In the red eft’s case, the warning color signals that the eft is a toxic meal. The red eft’s skin is poisonous to animals that eat it (but not to humans who touch it). Toads and snakes that swallow a red eft have been known to throw it up – unharmed – half an hour later. It’s no surprise that these predators quickly learn to avoid red efts.
There are always exceptions. Bullfrogs and turtles can eat red efts, and raccoons sometimes wash them first and then eat them. Over many generations, garter snakes in some places have become somewhat immune to the red eft’s toxin.
What’s the story behind the poisonous skin? Glands in the red eft’s skin produce a toxin similar to TTX (tetrodotoxin), the poison in some pufferfish. Most of us have heard that certain pufferfish are a delicacy in Japan, as long as chefs carefully remove the poisonous parts.
Red efts with toxic skin are not so different from other amphibians. Many toads, frogs, and salamanders have skin that’s distasteful or sickening to predators, but not deadly. And we’ve learned about poison dart frogs of Central and South America from TV nature shows. Native peoples used the skin of these brightly colored frogs to make poison for their arrows and darts, in order to paralyze the animals they hunted.
Are the other life-stages of the red-spotted newt also poisonous? Adult red-spotted newts, which live in water and have dull colors, can survive in ponds and streams that contain fish because these adults, too, get protection from poison in their skin. Red efts are ten times more poisonous than adult red-spotted newts, but the poison still helps the adults to survive.
Thanks to the poison, adult red-spotted newts are the only salamanders in New England that can share waters with fish. Other salamanders in New England, such as spotted salamanders (Ambystoma maculatum) and blue-spotted salamanders (Ambystoma laterale), live on land as adults. In the spring they breed in vernal pools – which don’t contain fish because they usually dry up in the fall – and then return to nearby woods.
A red eft that you might see at this time of year may stay on land for 1-5 years. When it is mature enough to breed, it returns to water to become an adult, but it doesn’t necessarily go back to the same pond or stream it came from. For this reason, red-spotted newts can spread readily into new environments, including man-made ponds and roadside ditches.
Adult red-spotted newts are drab olive green or brown, but they get their name from two rows of small red spots bordered with black on their back. The red eft has these spots as well. If you peer into a pond or stream and see some salamander-like creatures on the muddy bottom, you may be looking at red-spotted newts. If you see the spots, you’ll know for sure.
Adult red-spotted newts are creatures of the water, but like red efts, they breathe with lungs. If their pond or stream dries up, they can live on land, hiding in damp places under rocks and logs, until the pond or stream fills again.
What about the life-stages that come before the red eft and the adult red-spotted newt? The newts start off as eggs, laid on plants in the water in the spring. They hatch into an immature stage called a larva, which is somewhat like a tadpole. It breathes with gills and develops into the red eft.
Why do we tend to see red efts in August and September? That’s when larvae are transforming into red efts and moving onto land. It can also be a time when red efts that have lived on land for years are returning to water, where they’ll develop into adults.
The larvae also produce some poison in their skin, but most – perhaps 98 percent – don’t survive to the red eft stage. Especially when they’re tiny, they’re food for all sorts of other creatures that are living or developing in the water. Older red-spotted newt larvae may even eat younger, smaller ones.
Our red-spotted newts are one of the most widespread salamanders in North America. European settlers probably created more environments for them, such as farm ponds. These days, as beavers return to Massachusetts (and to Westborough), recently flooded areas offer new places for the newts to live.
Yet like other amphibians, red-spotted newts are vulnerable to changes that humans cause in the environment. Their poisonous skin protects them from predators, but it is thin and easily absorbs harmful chemical pollutants from the environment. Acid rain and increased ultraviolet light may be bad for them. If climate change brings warmer temperatures and drought conditions, the damp and watery environments that they need may become scarce.