The Crab That Farms Its Own Food Underwater

A Sponge That Walks

If you were swimming off the coast of Australia and saw a piece of sponge moving across the sea floor, you might think your eyes were playing tricks on you.

But look closer…

That sponge isn’t just drifting.

It’s walking, because there’s a crab underneath it.

Meet Lamarckdromia beagle — a rare type of sponge crab that not only wears a living sponge like a hat… it also farms it, trims it, and carries it like a protective shield.

This isn’t a sponge for show — it’s a living tool, a chemical weapon, and possibly… a pet.

Who Is Lamarckdromia beagle?

Discovered off the coast of Western Australia, Lamarckdromia beagle is a newly described species (identified in 2022), and part of the Dromiidae family — a group of crabs known for using sponges and other soft materials as camouflage.

But this one takes things a step further.

Rather than just picking up a random sponge, it chooses specific living sponges, trims them to size using its claws, and carefully places the sponge on its back — using its specially adapted rear legs to hold it in place like a little backpack.

And it doesn’t stop there.

This crab is believed to nurture the sponge, allowing it to grow, regenerate, and stay alive. It’s like a gardener with a mobile garden on its shell.

Why Carry a Sponge?

You might be wondering: what’s the point?

Turns out, the sponge is not just camouflage — it’s also chemical protection.

Sponges are famous for producing toxic or distasteful chemicals to keep predators away. Some contain anti-fungal, anti-bacterial, and even anti-cancer compounds. When a crab wears a live sponge, it gains access to that chemical defense system — without having to produce any toxins itself.

In short: the crab borrows the sponge’s “superpowers.”

And unlike dead materials like shells or leaves, the sponge grows with the crab, meaning it doesn’t need to keep finding new ones as it gets bigger.

Trimming and Shaping

What’s even more fascinating is how precise this crab is.

Using its front claws, Lamarckdromia beagle cuts the sponge into a perfect shape — trimming holes, rounding edges, and making sure it fits snugly on its back.

Researchers have seen crabs cut their sponges into semi-circular caps with holes for their legs to move freely, like a wearable costume.

It’s DIY armor.

Made by the crab.

Worn every day.

A Rare Case of Animal Tool Use?

In the animal kingdom, tool use is rare — and usually associated with clever animals like primates, birds, and dolphins.

But sponge crabs blur the line.

They don’t just wear something — they select, modify, and maintain a living organism for their benefit. That ticks several boxes in the definition of tool use. It’s like carrying a living umbrella that also fights bacteria.

Imagine wearing a hat that grows, heals itself, and defends you from attackers — that’s basically what this crab is doing.

The Sponge Doesn’t Mind?

Here’s the strangest part: the sponge seems to benefit too.

Instead of being torn apart or discarded, the sponge continues to grow while being carried. It gets access to fresh water currents and food particles as the crab moves around.

So what started as one-sided use may actually be a symbiotic relationship — both crab and sponge benefiting from each other.

It's like a walking reef partnership.

Hidden Heroes of the Sea Floor

These crabs aren’t flashy.

They don’t swim fast.

They don’t have claws like a coconut crab or colors like a mantis shrimp.

But they are quiet geniuses — masters of disguise and design, turning the sea floor into a toolbox.

In a world where survival depends on creativity, Lamarckdromia beagle proves that sometimes, the smartest move is to borrow nature’s defenses — and wear them proudly.