November 22, 2022

Rare six-legged terrapin hatchlings found near Boston

There’s another creature on the square, and it has six legs. Twice as pleasant: Two-headed diamondback reptile hatchlings with six legs in Massachusetts! The uncommon types of turtle was found for this present week by specialists from Tufts University and the New England Aquarium close to Boston.

“We’ve been looking for the last three years at least, and we’re going to keep looking”, Fredric Janzen, a herpetologist from Iowa State University. While it’s not unheard of for diamondback terrapins to hatch with four legs – they usually have eight – six is very unusual, to say the least.

We have never seen anything like this. They are certainly unique, said Dr. Ila France, the director of veterinary services at the New England Aquarium in Boston, Massachusetts.

Diamondback Terrapins are only found along the Atlantic coast. Due to coastal development and drainage of wetlands, their numbers have severely declined over the past 25 years. Their population is still in decline, which is why it’s so critical to understand the true state of their health.

We have so many questions, said Janzen. How does this happen? Is it just one of those weird things where an egg gets stuck in the wrong place and then they grow? I’m not sure we’ll ever know.

It’s probably a one-in-a million chance, said Dr. France. I don’t think we’re going to see this again in my lifetime.

The rare discovery was published in The Journal of Experimental Biology’s October issue.

Short-lived hexapod female embryos are not unprecedented among vertebrates; for example, branched (six-limbed) patterning has been reported for limb buds of mice and chickens. However, the formation of hexapod male embryos has never been observed in vertebrates; this is an extremely rare example of a naturally occurring birth defect associated with sexual dimorphism.

Evidence indicates that the abnormal phenotype results from failure of apoptosis-mediated programmed cell death during limb development.

We propose that double-bonded limbs might result from the deletion of cells in the fourth and fifth positions on each side of the limb bud, causing branched limbs to adopt a hexapod configuration.

Thus, our results suggest that there are common developmental mechanisms operative in the development of hexapoda across phylogenetically distant taxa.