Happy World Turtle Day!

May 23 marks World Turtle Day, an annual event that “helps people celebrate and protect turtles and tortoises and their disappearing habitats around the world,” according to the official World Turtle Day website.

A nonprofit called the American Tortoise Rescue, founded in 1990, sponsors the event, which got its start nearly 20 years ago.

Many biologists believe tortoises and turtles could disappear from the wild altogether in the next 50 years, according to the American Tortoise Rescue. More specifically, six species of sea turtle -- green, hawksbill, Kemp's ridley, leatherback, loggerhead and olive ridley -- are federally protected by the Endangered Species Act of 1973, according to the National Oceanic and Atmospheric Association.

Poaching, habitat destruction and accidental capture are just some of the factors that have lead to their endangered status.

In light of World Turtle Day, which is not the same as World Sea Turtle Day, here are three facts you should know.

Is there a difference between a tortoise and a turtle?

While “all of them are turtles,” San Diego-based wildlife biologist Sheila Madrak previously clarified to National Geographic that tortoises are typically land-bound, while turtles “can be aquatic, semi-aquatic, or mostly terrestrial.”

Can’t tell the difference? Look at the feet, Madrak suggested.

A tortoise has feet that are “designed for trucking around on land,” and can look like “tiny elephant feet,” she said.

Meanwhile, turtles have webbed feet that are equipped for swimming, while only sea turtles have flippers, National Geographic noted.

The oldest turtle in the world is reportedly more than 180 years old

Jonathan, a now 186-year-old tortoise, is allegedly the oldest of his kind and the oldest living land animal.

Jonathan, who resides on the South Atlantic island of St. Helena, made news in October 2017 when it was reported that Federica, a fellow tortoise he’s been smitten with for the last 26 years, could possibly be male. A shell deformity has stumped scientists on Federica's exact sex.

“It’s unsure,” Catherine Man, the island’s vet, told Fox News at the time. “She could be male, she could be female.”

Pet owners are urged to be cautious of turtles

While they may be cute, the U.S. Food and Drug Administration (FDA) warns that small turtles “commonly carry Salmonella bacteria on their outer skin and shell surfaces.”

The bacteria can cause serious health issues, such as vomiting, fever, headaches, diarrhea and stomach pain. While most people recover in a matter of days, according to the FDA, some cases can be life-threatening. For instance, in 2007, a 4-week-old baby died after contracting Salmonella from a turtle.

Lizards, snakes, frogs, salamanders and newts also carry the bacteria, according to the FDA.