A tiny diamondback terrapin hatchling weighing just 5.2 grams has turned up with two distinct heads sharing a single shell, discovered at a protected nesting site in Wellfleet, Massachusetts. The rare find, described as an exceptionally rare two-headed turtle, is now under close watch at a Cape Cod wildlife clinic as staff figure out how its two heads and bodies coordinate.
Staff from Mass Audubon's Wellfleet Bay Wildlife Sanctuary discovered the hatchling during routine nest monitoring before transporting it to the Cape Wildlife Center in Barnstable for medical assessment, according to NDTV. The condition is called bicephaly, and a veterinary team at the center is now monitoring how the turtle's two heads and bodies work together, tracking its appetite, growth and behavior in the days ahead, per the Kansas City Star.
“Both sides are behaving normally and looking very good,” said Zak Mertz, CEO of New England Wildlife Centers, per the same account. Bicephaly can occur in reptiles and other animals, and the Cape Wildlife Center has treated turtles with the condition before — the facility reportedly encountered two other bicephalic turtles within the past five years, in addition to this latest hatchling.
A Familiar Case for Cape Cod Rehabbers
This isn't the first time the Barnstable clinic has cared for a two-headed diamondback terrapin. On September 22, 2021, the Cape Wildlife Center brought in another bicephalic hatchling nicknamed “Mary-Kate and Ashley,” and diagnostic X-rays at the time revealed the animal had two distinct gastrointestinal tracts, a partially shared spine, and six legs, with each head controlling three legs of its own, according to Popular Science.
The anomaly traces back to early embryonic development, when conjoined twin embryos fail to fully separate. Diamondback terrapins live in coastal salt marshes and brackish waters, where fresh water and salt water mix, making Wellfleet's protected marshland exactly the kind of habitat where such nests are found and watched closely.
Why Every Hatchling Counts on the Cape
Wellfleet holds particular significance for the species: it serves as the northernmost breeding territory in North America for the northern diamondback terrapin, according to Mass Audubon. Diamondback terrapins are listed as a threatened species in Massachusetts, and Mass Audubon's Wellfleet Bay Wildlife Sanctuary has tracked local terrapins since the 1980s and actively protected nests since 2005.
The stakes extend well beyond Cape Cod. In July, NOAA Fisheries announced that diamondback terrapins may warrant listing under the federal Endangered Species Act and would advance to the next stage of review, as detailed by the Center for Biological Diversity. Wetland loss, turtles drowning in crab traps, and rising sea levels were cited as major drivers behind that decline.
Vehicle traffic along coastal roadways adds another layer of risk, since female terrapins migrate from salt marshes to find dry, sandy nesting sites during June and July. To help offset these losses, Massachusetts wildlife organizations have released thousands of hatchlings.
A Clinic Used to the Unusual
The Cape Wildlife Center is no stranger to odd cases crossing its doors. Beyond two-headed turtles, the Barnstable facility has rehabilitated a coyote pup that was mistaken for a lost puppy in 2022, according to CBS News. NBC10 Boston also shared video of the newly discovered hatchling.
For now, the hatchling remains under observation as staff track its progress. Its story adds to a growing local conversation about terrapin survival.
