Float Like a Crab, Sting Like an Anemone: Meet the Ocean’s Deadliest Cheerleaders

The Cutest Little Brawlers in the Indo-Pacific

If you were to rank the ocean’s creatures by how much they look like they belong on a high school cheerleading squad, the pom-pom crab would take the top spot. Also known as Hawaiian boxer crabs, these tiny crustaceans belong to the exclusive Polydectinae subfamily—a small VIP club of about a dozen species.

Native to the shallow, sunny coral reefs of the Indo-Pacific, these little guys are undeniably adorable, making them absolute rockstars in the aquarium trade. But don’t let their petite size and cute outfits fool you. Those “pom-poms” they are holding? They aren’t made of fluffy yarn.

Venomous Accessories and Crab Fight Clubs

Instead of spirit fingers, the pom-pom crab dual-wields a pair of highly venomous sea anemones (specifically, Triactis producta). They carry one anemone in each claw and literally wave them around at predators and random passersby like a grumpy old man shaking his fist from the porch—if his fist was made of poison.

But these fleshy boxing gloves aren’t just for shooing away the paparazzi. The crabs actively use the anemones to spar with rival crabs in tiny, underwater fight clubs, and to stun and snatch up their next meal.

The Ultimate Aquatic Ride-Share

The ocean is full of roommates, and crab-anemone symbiotic relationships are actually pretty common. You’ve got decorator crabs and hermit crabs hauling anemones around on their backs like living backpacks.

But the pom-pom crab’s true mutualism setup is a bit more hands-on (literally). While both the crab and the anemone could technically survive on their own, life is just better together. The crab gets a pair of venomous tasers to ward off predators, and the anemone gets free Uber rides around the reef with complimentary access to the crab’s messy dinner leftovers. It’s a win-win, assuming you aren’t the guy getting punched by a toxic pom-pom!

How do pom-pom crabs acquire their anemones? Do they steal them or grow them?

The answer is actually both—they steal them and they grow them!

Here is how these tiny crustaceans manage to keep their claws fully armed:

The Great Anemone Heist

When a pom-pom crab finds itself empty-handed (or empty-clawed), it doesn’t just wander the reef looking for a wild anemone to pick up. Instead, it tracks down another pom-pom crab and initiates a tiny underwater wrestling match. The crab without anemones will try to pin down its opponent’s claws and snatch at least one anemone—or even just tear a chunk off.Surprisingly, these muggings usually end with a successful theft and no actual injuries to either crab.

The Cloning Process

Once the crab manages to secure a single anemone, it does something completely wild. Using its claws, the crab carefully stretches the lone anemone and tears it directly in half. Over the next few days, those two torn fragments regenerate into two fully functional, genetically identical clones—giving the crab a matching set of pom-poms once again.

A Scientific First

This quirky behavior is actually a massive deal in biology. It is the very first known case in nature of one animal intentionally forcing another animal to reproduce asexually.

In fact, the crabs and anemones are so codependent that when researchers extensively searched the Red Sea reefs for this specific type of anemone, they couldn’t find a single one living freely on the rocks.Every single anemone they found was attached to a crab, suggesting that these anemones might rely almost entirely on the crabs stealing and ripping them apart just to sustain their population!

Reference https://zooatlanta.org/the-fascinating-subfamily-polydectinae/ https://www.livescience.com/animals/crustaceans/pom-pom-crab-the-crustacean-that-uses-anemones-as-boxing-gloves https://www.sciencedaily.com/releases/2017/01/170131075121.htm#:~:text=A%20first%20experiment%20showed%20that%20when%20a,with%20one%20which%20had%20its%20anemones%20removed.