'Hard-headed little guy': Sea turtle gets an autopsy
The turtle's eyes are gently shut, like it's taking a nap and its blood isn't dripping onto the concrete below. Like its heart hasn't traveled around the semicircle, passed between red-smeared gloves. Like its head isn't detaching under the rapid slices of biologist Matthew Godfrey's hacksaw.Posted — Updated
A few feet away from the turquoise water, about 17 UNC-Chapel Hill undergraduates form a loose semicircle, with the breeze fluttering their T-shirts and shorts. They’re at UNC’s Institute of Marine Sciences, standing on a loading dock that hoists wooden pallets and nitrogen gas tanks and 80-below-zero freezers.
A sour scent floats up their noses: roadkill with a tinge of the sea.
The star of the show, identified as a green sea turtle, lies atop the upside-down lid of a plastic storage bin, elevated by a white folding table for the students’ viewing. Barnacles and algae dot the gray-green shell. The turtle’s eyes are gently shut, like it’s taking a nap and its blood isn’t dripping onto the concrete below. Like its heart hasn’t traveled around the semicircle, passed between red-smeared gloves. Like its head isn’t detaching under the rapid slices of biologist Matthew Godfrey’s hacksaw.
“It’s the noise!” one student says, cringing.
“Yeah, that’s what freaks me out more than the turtle,” says another.
“Hard-headed little guy!” Rachel Noble, a professor at the UNC-Chapel Hill Institute of Marine Sciences, says. She’s seen about 18 turtles undergo this process, and she’s grateful this one isn’t as stinky as some of the others.
Godfrey reaches the brain.
“Oh my gosh!”
“It is small,” Godfrey says. “And yet, it does everything it’s supposed to do. It migrates. It finds where it’s supposed to go.”
This necropsy — the animal kingdom’s equivalent of an autopsy — is a demonstration for educational purposes. But it’s bigger than the classroom. Godfrey, a state sea turtle biologist for the North Carolina Wildlife Resources Commission, is walking the students through a process he completes anywhere between 50 and 100 times every year. He’ll submit the data he finds to the federal government’s sea turtle stranding office, which will use it to make decisions about environmental concerns like fisheries and dredging.
Six species of sea turtles swim in U.S. waters, and five of them are found off North Carolina. They’re all protected by the Endangered Species Act and state law. Godfrey helps coordinate the state’s Sea Turtle Stranding and Salvage Network, a group that responds to calls about troubled turtles and goes on patrol looking for them. When turtles like this one are found sick, injured or dead, the network is required by law to fill out a standardized form with the facts of the situation: who found it, when they found it, where they found it, whether it had any tags on its flippers or inside its body.
This turtle looks plucked straight from the ocean. It’s hard to tell that it sat in a freezer for more than a year and a half, saved for a workshop like this one. It died young: Judging from the turtle’s size, Godfrey estimates it’s about 5 years old, whereas the maturity age for its regional population hovers around 40.
Mansi Sakarvadia, a junior, looks on. Like many of her classmates, this is her first time seeing a turtle cut open.
“It’s really sad — I mean, it's sad that it died,” she says. “Not sad that once it's dead, we're figuring out the cause of death and hopefully alleviating it. But they found 21 dead turtles in one day — that was the 21st one on that one day. So, that's sad.”
The “2021” painted on the dead turtle’s shell is deceiving: The ‘20’ actually represents the year 2020, while the ‘21’ signifies that it was the 21st turtle that the Sea Turtle Stranding Network found that day. It was alive and cold-stunned at the time, washed up from Pamlico Sound on the shore of Cape Hatteras. It died overnight at the Sea Turtle Assistance and Rehabilitation Center in Manteo.
Even before the necropsy, it was clear how the turtle met its end. Pamlico Sound is a foraging hotspot for juvenile green sea turtles. When the water gets cold — and it does quickly, due to its shallowness — the turtles leave for warmer waters. But sometimes cold snaps catch them by surprise, and they can’t find their way out in time.
For the past 10 years, the network has recorded at least 100 cold-stunned turtles. In some particularly chilly years, it’s recorded up to 2,000. Godfrey says there’s some debate about whether climate change is contributing to these cold stuns.
“Maybe that's exacerbated swings in temperature that might result in hypothermia in turtles,” he says.
The network comes across turtles in all sorts of dilemmas: weakened with disease, struck by a boat, stuck in a dredge, caught on a fishing hook, trapped in commercial fishing gear like gill nets or pound nets, swept up in an intake canal at a power plant.
“Luckily, this one seems like he just died because it was too cold,” junior Logan Timm says, standing near the table. “Which, I mean — not that it makes it OK, but it makes it a little more OK.”
With each organ Godfrey uncovers, the students let out oohs and aahs, sounding more fascinated than disturbed. They feel the soft head, the leathery nose. They see its huge shoulder muscles — important for swimming long distances toward the Gulf Stream or down to Florida — which take up so much space that Godfrey has to cut them out. They observe the smooth shoulder joint; this turtle doesn’t have arthritis.
“We have seen that in some turtles. Older turtles, not young ones like this. Not like you guys with your perfect joints,” Godfrey says. “Did everybody get a chance to touch the joint?”
The organ muscles feel like steak or chicken breast, Godfrey says, and some people harvest it around the world. He points out the dark fat that you can boil into greenish turtle soup.
“It's kind of eerie — well, not really eerie, but it's cool how similar their bodies are to ours,” senior Natalie Patetta says. “Like, our lungs are in the back; theirs are in the back. Our kidneys are in the back — there's two. We have similar muscles, but not exactly the same muscles, for the esophagus.”
No fish hooks caught in the esophagus. No bruising on the brain to indicate a boat strike. No plastic in the stomach — just seagrass, the green sea turtle’s snack of choice.
“I think the only thing that was wrong with this turtle: It was in the wrong place at the wrong time,” Godfrey says.
Godfrey also needs to discern the turtle’s sex. When green sea turtles are adults, it’s easy to tell: The males have an enlarged claw to help them latch onto the females while mating. But when they’re juveniles, you have to poke at the gonads.
Godfrey is able to push the gonads around; that means they’re ovaries, not testes. About two-thirds of the turtles that the Sea Turtle Stranding Network opens up are females.
A turtle’s sex is determined by the incubation temperature the eggs experience while in the nest. Godfrey says climate change has led to concerns that as nesting beaches heat up, more hatchlings will come out female, and the population won’t have enough males to fertilize eggs.
“So, one of the things we'd like to do is to keep track of the juveniles to see, has there been a change over time?” Godfrey says.
By the time Godfrey’s work is done, the turtle is reduced to a shell filled with loose organs. Next, the parts will go to an approved dumping place in a forest: They’re required to be disposed of in an area where humans won’t get to them, as even the carcasses are protected by law.
There are a few stops ahead for Godfrey, too. There’s the Stranding Network’s database, where Godfrey will enter the data and transfer it to the federal database. There are annual reports to produce and research projects to collaborate on. And there are meetings, where he’ll plan for the next cold-stun season.
“All indications are that this turtle was happy, healthy, doing its thing,” Godfrey says. “It just got too cold.”
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