10 Ginormous Facts About Coconut Crabs

Janos/iStock via Getty Images
Janos/iStock via Getty Images

They're huge and antisocial. They will steal your silverware and can rip apart whole coconuts with their claws. Grab a piña colada and enjoy these 10 ginormous facts about the amazing coconut crab.

1. Coconut crabs are colossal.

Native to islands in the Indian and southern Pacific oceans, are truly humongous. They can weigh 9 pounds and measure 3 feet from leg to leg. Coconut crabs are the largest land-living arthropods—the phylum of joint-legged creatures that includes crabs, insects, spiders, and scorpions. Even Charles Darwin was stunned by their “monstrous size.”

But be aware: Occasionally, a viral photo circulates that exaggerates the coconut crab’s size. As biologist Michael Bok explains, the coconut crab in that infamous photo is normal sized, but the trash can is unusually small.

2. Coconut crabs are actually hermit crabs.

Sandwich, Flickr // CC BY-NC-ND 2.0

Where does such a bizarre animal fit in the animal kingdom? Are they lobsters? Tarantulas? Space aliens? In fact, Birgus latro is a kind of hermit crab.

You may have seen smaller hermit crabs on a trip to the beach—or for sale at a pet shop. They take shelter inside abandoned snail shells, carrying them around as portable homes. But if coconut crabs are hermit crabs, then why don’t they live in shells? Well, they do—when they’re young and still small.

3. Coconut crabs quickly outgrow their borrowed shells.

Like other crabs, hatchling coconut crabs begin their lives floating freely at sea. After about a month of eating and growing, they find a snail shell and move in. The little coconut crabs carry this mobile home as they begin to transition to a land-based life.

A seashell is a nice, protected place to live, but it has its drawbacks [PDF]. As a crab gets bigger, its shell gets tighter—like an old pair of shoes on a kid who’s growing fast. The crab needs to find a bigger shell and make a quick switch. And that larger home will be heavier to tote around.

So, after a year or so of inhabiting shells, the coconut crab makes a major lifestyle change. It crawls out and hardens the parts of its body that were once protected by the shell by regrowing layers of calcium-based tissues, a process called recalcification. Without its old home, it’s free of size constraints. Now, unlike other hermit crabs, it can become enormous.

4. Coconut crabs eat coconuts, of course ...

This might seem obvious from the coconut crab’s name. But if you’ve ever tried to crack open a coconut, you know that it’s a steep challenge. In fact, a lengthy scientific debate once raged about whether coconut crabs were really able to open the fruit. It turns out that they’re up to the challenge—but they don’t just pop open their prize and dig in.

Breaking into a coconut is a mighty ordeal even if you’re a heavily armored crustacean the size of a small dog. Coconut crabs first use their claws to scrape away the fibrous coating. This can take hours or days. Finally, they stab into the fruit at a weak point and rip it open.

This diet helps coconut crabs grow large: those with access to coconuts may be twice as massive as those without. But eating the fruit isn’t essential for their survival. So what other items do the largest land-living arthropods shove into their maw?

5. ... but they also eat dead animals, their own body parts, and each other.

As well as the occasional biscuit, as you can see in the video above. (Note: Do not feed biscuits to coconut crabs.) A coconut crab’s diet may include other tropical fruits, fallen plant material, dead and decaying animals, rats, and other crab species. They’ll even eat members of their own kind. In fact, biologist Mark Laidre says they only relatively recently evolved to eat coconuts—a skill unique to modern coconut crabs—which helps them to eat each other less.

They also eat their own discarded body parts. As coconut crabs grow, they periodically molt their tough outer layer (the exoskeleton) and grow a new one. Once they’re done molting, which takes about a month, they gobble up their own exoskeleton.

6. Coconut crabs have an amazing sense of smell ...

Coconut crabs often forage at night. How do they find food when they’re wandering around in the dark? They sniff it out. These animals have a strong, highly efficient [PDF] sense of smell. In fact, a large portion of their brain is devoted to detecting odors.

7. ... which might explain why they're thieves.

Coconut crabs are also known as robber crabs because they snatch silverware and other objects and carry them away. Some people have even advanced the gruesome theory that Amelia Earhart’s remains are missing because coconut crabs hauled them down into their burrows. The thievery might be tied to that incredible sense of smell. Coconut crabs ignore objects that have been washed clean of scents, suggesting that they may only abscond with things that carry a faint whiff of food.

8. Coconut crabs are pretty antisocial.

Adult coconut crabs live alone in crevices or burrows. They aggressively guard their privacy; a crab entering another’s burrow risks becoming a meal.

But that’s not the end of their antisocial behavior. When coconut crabs emerge to feed, they keep their distance from each other. To maintain their personal space, they’ll announce their presence with ritualized claw waving. Laidre sought to find out if coconut crabs ever gathered together to interact (beyond mating or eating each other). The scientist tethered coconut crabs to one spot and watched to see if any others came to visit. They did not.

9. Coconut crabs carry their developing young under their abdomens.

After coconut crabs mate, females attach their eggs to special appendages and carry them under their abdomens. While the young develop inside the eggs, the females hold onto them, sticking near the edge of the sea so that they can periodically moisten the eggs.

But this care ends when the young are ready to hatch. The females release their hatchlings into the ocean waves. Now the tiny, floating babies must fend for themselves—and only a few will survive to return to land.

10. We need to learn a lot more about coconut crabs.

Anne Sheppard, Wikimedia Commons // CC BY 3.0

Coconut crabs are little-studied creatures, and we need to know more about them—not just because they’re incredible and have a lot to tell us about biology, but also because we want to keep them around.

They may be huge and heavily armored, but they can be vulnerable. Coconut crabs take an extremely long time to grow big—they can live more than 40 years—and introduced predators such as rats can harm smaller, younger individuals or those in the process of shedding their exoskeletons (when their bodies are soft). Habitat loss has also caused local declines in some areas. The International Union for Conservation of Nature lists the coconut crab as data deficient: That is, we don’t know enough about its locations and populations. That’s why we need to study and learn more about these amazing, otherworldly critters.

14 Retro Gifts for Millennials

Ravi Palwe, Unsplash
Ravi Palwe, Unsplash

Millennials were born between 1981 and 1996, which means the pop culture they grew up with is officially retro. No matter what generation you belong to, consider these gifts when shopping for the Millennials in your life this holiday season.

1. Reptar Funko Pop!; $29

Amazon

This vinyl Reptar figurine from Funko is as cool as anything you’d find in the rugrats’ toy box. The monster dinosaur has been redesigned in classic Pop! style, making it a perfect desk or shelf accessory for the grown-up Nickelodeon fan. It also glows in the dark, which should appeal to anyone’s inner child.

Buy it: Amazon

2. Dragon Ball Z Slippers; $20

Hot Topic

You don’t need to change out of your pajamas to feel like a Super Saiyan. These slippers are emblazoned with the same kanji Goku wears on his gi in Dragon Ball Z: one for training under King Kai and one for training with Master Roshi. And with a soft sherpa lining, the footwear feels as good as it looks.

Buy it: Hot Topic

3. The Pokémon Cookbook; $15

Hop Topic

What do you eat after a long day of training and catching Pokémon? Any dish in The Pokémon Cookbook is a great option. This book features more than 35 recipes inspired by creatures from the Pokémon franchise, including Poké Ball sushi rolls and mashed Meowth potatoes.

Buy it: Hot Topic

4. Lisa Frank Activity Book; $5

Urban Outfitters

Millennials will never be too old for Lisa Frank, especially when the artist’s playful designs come in a relaxing activity book. Watercolor brings the rainbow characters in this collection to life. Just gather some painting supplies and put on a podcast for a relaxing, nostalgia-fueled afternoon.

Buy it: Urban Outfitters

5. Shoebox Tape Recorder with USB; $28

Amazon

The days of recording mix tapes don’t have to be over. This device looks and functions just like tape recorders from the pre-smartphone era. And with a USB port as well as a line-in jack and built-in mic, users can easily import their digital music collection onto retro cassette tapes.

Buy it: Amazon

6. Days of the Week Scrunchie Set; $12

Urban Outfitters

Millennials can be upset that a trend from their youth is old enough to be cool again, or they can embrace it. This scrunchie set is for anyone happy to see the return of the hair accessory. The soft knit ponytail holders come in a set of five—one for each day of the school (or work) week.

Buy it: Urban Outfitters

7. D&D Graphic T-shirt; $38-$48

80s Tees

The perfect gift for the Dungeon Master in your life, this graphic tee is modeled after the cover of the classic Dungeons & Dragons rule book. It’s available in sizes small through 3XL.

Buy it: 80s Tees

8. Chuck E. Cheese T-shirt; $36-$58

80s Tees

Few Millennials survived childhood without experiencing at least one birthday party at Chuck E. Cheese. This retro T-shirt sports the brand’s original name: Chuck E. Cheese’s Pizza Time Theatre. It may be the next-best gift for a Chuck E. Cheese fan behind a decommissioned animatronic.

Buy it: 80s Tees

9. The Nightmare Before Christmas Picnic Blanket Bag; $40

Shop Disney

Fans of Tim Burton’s The Nightmare Before Christmas will recognize the iconic scene on the front of this messenger bag. Unfold it and the bag becomes a blanket fit for a moonlit picnic among the pumpkins. The bottom side is waterproof and the top layer is made of soft fleece.

Buy it: Shop Disney

10. Toy Story Alien Socks; $15

Shop Disney

You don’t need to be skilled at the claw machine to take home a pair of these socks. Decorated with the aliens from Toy Story, they’re made from soft-knit fabric and are big enough to fit adult feet.

Buy it: Shop Disney

11. Goosebumps Board Game; $24

Amazon

Fans that read every book in R.L. Stine’s series growing up can now play the Goosebumps board game. In this game, based on the Goosebumps movie, players take on the role of their favorite monster from the series and race to the typewriter at the end of the trail of manuscripts.

Buy it: Amazon

12. Tamagotchi Mini; $19

Amazon

If you know someone who killed their Tamagotchi in the '90s, give them another chance to show off their digital pet-care skills. This Tamagotchi is a smaller, simplified version of the original game. It doubles as a keychain, so owners have no excuse to forget to feed their pet.

Buy it: Amazon

13. SNES Classic; $275

Amazon

The SNES Classic is much easier to find now than when it first came out, and it's still just as entertaining for retro video game fans. This mini console comes preloaded with 21 Nintendo games, including Super Mario Kart and Street Fighter II.

Buy it: Amazon

14. Planters Cheez Balls; $24

Amazon

Planters revived its Cheez Balls in 2018 after pulling them from shelves nearly a decade earlier. To Millennials unaware of that fact, this gift could be their dream come true. The throwback snack even comes in the classic canister fans remember.

Buy it: Amazon

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Treat Your Feline This Holiday Season With Fancy Feast’s Cat Food Advent Calendar

Fancy Feast/Chewy
Fancy Feast/Chewy

In anticipation of the holiday season, many children and adults get to unwrap mini presents each of the 24 days leading up to Christmas day, during what's known as Advent. Though Advent itself dates back to the 4th century, the version we know today, complete with the chocolate-filled calendars, was popularized in the early 1900s. And apparently it's no longer just for humans, because Fancy Feast is letting your feline roommate in on the fun with this unique cat food Advent calendar, now available at Chewy for $23.

For the 24 days leading up to Christmas, your cat will get to enjoy a variety of different wet foods, including favorites like grilled salmon, chicken, and more. There is even a unique ornament included with each calendar featuring a cat in the shape of a heart that can go right onto your tree. (Also, don't be surprised to find your actual cat making its way into the middle of your tree; they're known climbers.)

Now while you enjoy your Advent calendars from brands like LEGO, Funko, and more, your cat will be able to join in on the fun as well. To learn more about Fancy Feast's Feastivites Advent Calendar, head on over to Chewy.

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