13 Facts About Nurse Sharks

iStock.com/Divepic
iStock.com/Divepic

Known as the “couch potato of the shark world,” the nurse shark (Ginglymostoma cirratum) leads a sedentary life. By day, it rests, and by night, it creeps over the sandy floors and coral reefs of its shallow-water habitat, slurping up little animals along the way.

But though it's not a fast or aggressive fish, you should give it plenty of space: People who act carelessly around nurse sharks risk serious injuries. Here are 13 things that every ocean-lover ought to know about the nurse shark.

1. IT USES A METHOD CALLED BUCCAL PUMPING TO BREATHE.

For certain sharks, lying on the ocean floor is an impossibility. Species like the great white and the whale shark breathe by swimming nonstop; as they travel around, water is constantly flowing into their open mouths and across their gills, supplying oxygen en route. If the fish stop moving for too long, that flow ceases and they die. But other species are perfectly capable of breathing while sitting still—including the nurse shark. By using oral muscles to actively suck water into the mouth—what's called buccal pumping—it can supply oxygen to the gills without needing to swim anywhere.

2. THEY CAN "WALK" ACROSS THE OCEAN FLOOR.

Wild nurse sharks are usually found in shallow, coastal waters. The fish are nocturnal predators who tend to hunt within 65 feet of the ocean’s surface (although adults sometimes rest in deeper waters during the daylight hours). They spend their lives around coral reefs and coastal shelves, and most of their hunting takes place right on the ocean floor, where these slow-moving carnivores look for prey in or near the sand. Instead of swimming, they sometimes use their pectoral fins to “walk” across the bottom.

3. THE TWO LITTLE KNOBS ON THEIR FACES ARE CALLED “BARBELS.”

Barbels are fleshy sense organs that contain taste buds, which they drag across sand in search of prey.

4. THEY SUCK UP THEIR FOOD.

Nurse sharks eat a variety of sea life, from conchs, squid, and sea urchins to bony fish. A cavity within the throat generates a powerful suction which vacuums hapless animals up into the nurse shark’s mouth, where rows of tiny, backward-curving teeth crush up the food.

The mouth works like a dental conveyor belt; new rows of teeth pop up towards the back and gradually push older ones forward until they fall out. How long an individual row lasts depends on the season. During the winter, a nurse shark will acquire a fresh row of teeth every 50 to 70 days. But in the summer, tooth row replacement occurs every 10 to 20 days.

5. THE SPECIES COMES IN A FEW DIFFERENT COLORS.

Full-grown nurse sharks are usually brown, but they can also be grey or yellowish. In 1992, a “milk white” individual with brown splotches was caught and photographed near Key Largo, Florida. The fish might have been piebald, which is a genetic condition that’s similar to albinism. Piebald animals have a combination of normally colored skin and patches of pigment-deficient white skin. Another mature nurse shark who fit this general description was filmed in 2014. Adult specimens don't normally have spots, but as juveniles, the fish are covered in little black dots that fade as they age.

6. IT LIKES TO UNWIND IN BIG GROUPS.

Shark snuggle parties are a thing. By day, the nocturnal nurse shark becomes inactive; for hours on end, it just lies around and pumps water over its gills. Crevices, ledges, and piles of boulders are popular downtime locations for this species. Although the sharks don't socialize on hunting trips, they often recline en masse. Nurse sharks are known to rest communally, with groups of two to 40 individuals piling up on top of each other.

7. ADULTS CAN BE OVER 10 FEET LONG.

The maximum reliably-measured length for this species is 10.1 feet. As far as weight goes, the heaviest adult ever reported to the International Game and Fish Association was a 263.8-pounder caught by two fishermen (a father and his 15-year-old son) in 2007. Day-old pups are 7.8 to 12 inches long—and a batch of premature nurse sharks who were measured by scientists after being born near-term weighed between 4.2 and 5.3 ounces apiece. Big things can start out small.

8. NOBODY KNOWS WHERE THE NAME “NURSE SHARK” CAME FROM.

It’s definitely not qualified to care for hospital patients, so why did people start calling this barbel-faced sea critter the “nurse” shark? That’s a linguistic mystery, but historians have their theories. Maybe the suction-based feeding methods reminded sailors of nursing infants. Alternatively, the nurse in nurse shark could be descended from “huss,” an archaic name given to an unrelated family of bottom-dwellers. (We now call them “catsharks.”) Over time, huss evolved into nuss, a word that came to mean “shark” or “large fish.” So perhaps the nurse shark moniker is based on a corruption of nuss.

9. THE WHALE SHARK IS A RELATIVE.

Approaching 40 feet in total length and weighing several tons, adult whale sharks are the biggest fish presently alive. Like the nurse shark, this species eats via suction, and that’s not where the resemblance stops. Whale and nurse sharks are both members of the order Orectolobiformes, a group of 39 shark species largely in temperate and tropical oceans. Also known as “carpet sharks,” they're characterized by having small mouths that—when viewed in profile—do not extend behind the eyes. All of these fish have two dorsal fins on their backs and five sets of gill slits. Species within this order tend to have striking patterns on their skins, with grown-up nurse sharks being an obvious exception. Barbels are another common feature.

The strangest member of Orectolobiformes might be the shaggy wobbegong sharks, who lie still on tropical sea beds and use brilliant camouflage to ambush unsuspecting fish from below.

10. NURSE SHARKS ARE PARTIALLY MIGRATORY.

Plenty of well-known sharks embark on huge migrations; hundreds of whale sharks from across the Atlantic visit Mexico’s Yucatan Peninsula every summer and Pacific great whites go on winter pilgrimages to a mysterious, mid-ocean site dubbed the “White Shark Café.” Nurse sharks are less prone to wanderlust; many remain in the same general area all year round.

But some of their peers might feel the travel bug from time to time. In January 2018, Environmental Biology of Fishes published a 23-year nurse shark tracking study. The scientists behind it looked at a wild population which uses the Dry Tortugas (part of the Florida Keys) as a mating ground. Altogether, they captured and recaptured 76 adult nurse sharks. Tagging revealed that some of these fish clung to the Dry Tortugas and neighboring islands throughout the year. However, others were venturing as far north as the Tampa Bay area in between mating seasons, making the shark “partially migratory.” That means some individuals within this species migrate, but others don't.

11. FEMALES DON’T GIVE BIRTH EVERY YEAR.

The nurse shark mating season lasts from May to July, during which females will mate with multiple males. Sometimes two, three, or more males will attempt to mate with the same female simultaneously, resulting in violent shoving matches.

Nurse sharks have a five- or six-month gestation period and give birth to litters of 20 to 40 live young. A single batch of newborn pups may include the offspring of up to six different fathers. After she’s given birth, a mother nurse shark won’t mate again for another 18 months.

12. BE WARNED: IT CAN DOLE OUT PAINFUL BITES!

Underestimate this animal at your own risk. Because nurse sharks are sluggish by nature, commonly kept in aquariums, and don't possess large teeth, a lot of people who swim or dive in their natural habitat assume that the fish aren’t dangerous. But these predators can crush clams between their teeth and generate enough suction to rip a full-grown conch right out of its shell—so you don’t want one latching onto your arm.

But that’s just what happened to a swimmer in Boca Raton, Florida, in 2016. The 23-year-old female victim had been out snorkeling with friends when a 2-foot-long nurse shark clamped down on her right arm. (Eyewitnesses reported that another group of beachgoers had been harassing it.) The shark remained there while the snorkeler was driven to a nearby hospital. She survived, but the shark died before the medical team showed up. In another 2018 incident, an Instagram model was bitten while posing in some nurse shark-inhabited shallows.

Nurse shark attacks are uncommon, but they’re certainly not unheard-of—and humans are usually to blame. YouTube is loaded with videos of scuba divers hugging, grabbing, or stroking wild nurse sharks. Docile and shy as nurse sharks are, they may bite when provoked—or if they mistake an arm or finger for food.

“People are playing with fire,” George Burgess, the longtime director of the International Shark Attack File database, told the Palm Beach Post. In an interview with Newsweek, Burgess said that “A nurse shark bite is one of the worst, because their teeth are like cheese graters on each side. When they get onto a human being, it’s like a vacuum cleaner … They leave a concave hole where they’ve turned flesh into hamburger.”

13. A NEW SPECIES OF NURSE SHARK WAS RECENTLY NAMED.

Ginglymostoma cirratum lives in the Caribbean, off the northeastern coast of South America, near Spain, along western Africa, and by the eastern U.S. seaboard. A 2012 study found that a population living in the tropical eastern Pacific was genetically and anatomically different enough from Atlantic nurse sharks to constitute its own species. Named Ginglymostoma unami, or the Pacific nurse shark, it has a couple of noticeable traits that set it apart from G. cirratum. For example, the newly named fish’s second dorsal fin lies closer to the tail [PDF]. The two species may have diverged from one another when tectonic plates collided about 3 million years ago, isolating the ancestral nurse shark populations on either side of the Panamanian land bridge.

Looking to Downsize? You Can Buy a 5-Room DIY Cabin on Amazon for Less Than $33,000

Five rooms of one's own.
Five rooms of one's own.
Allwood/Amazon

If you’ve already mastered DIY houses for birds and dogs, maybe it’s time you built one for yourself.

As Simplemost reports, there are a number of house kits that you can order on Amazon, and the Allwood Avalon Cabin Kit is one of the quaintest—and, at $32,990, most affordable—options. The 540-square-foot structure has enough space for a kitchen, a bathroom, a bedroom, and a sitting room—and there’s an additional 218-square-foot loft with the potential to be the coziest reading nook of all time.

You can opt for three larger rooms if you're willing to skip the kitchen and bathroom.Allwood/Amazon

The construction process might not be a great idea for someone who’s never picked up a hammer, but you don’t need an architectural degree to tackle it. Step-by-step instructions and all materials are included, so it’s a little like a high-level IKEA project. According to the Amazon listing, it takes two adults about a week to complete. Since the Nordic wood walls are reinforced with steel rods, the house can withstand winds up to 120 mph, and you can pay an extra $1000 to upgrade from double-glass windows and doors to triple-glass for added fortification.

Sadly, the cool ceiling lamp is not included.Allwood/Amazon

Though everything you need for the shell of the house comes in the kit, you will need to purchase whatever goes inside it: toilet, shower, sink, stove, insulation, and all other furnishings. You can also customize the blueprint to fit your own plans for the space; maybe, for example, you’re going to use the house as a small event venue, and you’d rather have two or three large, airy rooms and no kitchen or bedroom.

Intrigued? Find out more here.

[h/t Simplemost]

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A Wily Fox With a Passion for Fashion Stole More Than 100 Shoes From a Berlin Neighborhood

The smirk.
The smirk.
Brett Jordan, Unsplash

In Berlin, Germany, a fox has embarked on a crime spree that puts Dora the Explorer’s Swiper completely to shame.

CNN-News18 reports that residents of Zehlendorf, a locality in southeastern Berlin, spent weeks scratching their heads as shoes continued to disappear from their stoops and patios overnight. After posting about the mystery on a neighborhood watch site and reading accounts from various bewildered barefooters, a local named Christian Meyer began to think the thief might be a fox.

He was right. Meyer caught sight of the roguish robber with a mouthful of flip-flop and followed him to a field, where he found more than 100 stolen shoes. The fox appears to have an affinity for Crocs, but the cache also contained sandals, sneakers, a pair of rubber boots, and one black ballet flat, among other footwear. Unfortunately, according to BBC News, Meyer’s own vanished running shoe was nowhere to be seen.

Foxes are known for their playfulness, and it’s not uncommon for one to trot off with an item left unattended in a yard. Birmingham & Black Country Wildlife explains that foxes are drawn to “things that smell good,” which, to a fox, includes dog toys, balls, gardening gloves, and worn shoes. And if your former cat’s backyard gravesite is suddenly empty one day, you can probably blame a fox for that, too; they bury their own food to eat later, so a deceased pet is basically a free meal.

The fate of Zehlendorf’s furriest burglar remains unclear, but The Cut’s Amanda Arnold has a radical idea: that the residents simply let the fox keep what is obviously a well-curated collection.

[h/t CNN-News18]