How hermit crabs solve housing problems

Most animals form groups to protect themselves against harm or predators, or to procure food, and these behaviors have one thing in common: banding together to help one another. But, according to a new study, some hermit crabs socialize to less noble reasons: to evict their neighbors.

The crabs' behavior illustrates how a normally solitary animal can develop social traits to benefit itself, even at the expense of others. The study, led by Dr. Mark Laidre from the University of California, Berkeley, USA, was published in the October issue of Current Biology.

Most hermit crabs (about 800 species) live in the sea, and have an ample supply of empty shells to inhabit. As the crabs grow, they simply find a bigger shell. That's easy in the ocean, where many sea snail shells are available.

But, live is not so easy on land. There are far fewer shells, and most are usually occupied by another hermit crab. Dr. Laidre found that land hermit crabs uniquely remodel their shells, hollowing them out, and practically no land hermit crab can survive without such a hollowed-out shell.

So, what's a growing, about-to-be homeless crab to do? Dr. Laidre found that first, three or four crabs congregate, looking for snail shells that have washed up on the beach. Soon, many other crabs join them, all hoping to trade their shells for bigger ones. Then, the fighting begins. Each crab grabs another, and tries to yank it from its shell. Once a crab is evicted, another abandons its shell and moves into new quarters. This creates a chain reaction of sorts, with rapid successions of crabs replacing each other's shells.

There's always a loser or two, of course, Dr. Laidre tells The Munich Eye. "The one that gets yanked out of its shells is often left with the smallest shell, which it can't really protect itself with. It's liable to be eaten by anything".

The study shows that while animals and plants can create ecological niches to help them survive, sometimes the social behavior produced by this evolutionary pressure isn't always positive.
Laidre, M.E. (2012). Niche construction drives social dependence in hermit crabs. Current Biology, 22(20), R861-R863.

Add comment
Smile Sad Huh Laugh Mad Tongue Crying Grin Wink Scared Cool Blush Unsure Shocked Confused Thumbs up Thumb down

Scientists Explain Why Snails Have A Twisted Shell

Snails, as some other gastropods, have coiled shells, Dpp protein seems to be the clue
Molecules called morphogens control the shapes of organisms. One morphogen, Dpp, makes most snail shells coil to the right as described in a recent...

Researchers Create a Hangover-Free, Rehydrating Beer

Source: Wikipedia.
Researchers have crafted a new breed of beer, containing electrolytes like those found in sport drinks, decreasing the risk of dehydration (and...

Our Alien Gold

Source: Wikipedia.
    All the gold on earth is alien. Every atom of the precious metal probably came to us from violent collisions of dying stars, according to a team...

An Unlikely New Home For Insects

Credit:  Robert Tropek
Fly ash deposits, by-products of coal combustion produced around energy power stations, have been found to serve as an alternative home for many...

A single gene for claustrophobia?

Source: Wikipedia.
Do you panic when you are in a small space? Do you sweat, or shake; does your heart pound? A study in the March issue of Translational Psychiatry...

Snail reveals ancient human migration routes

Credit: Wikipedia Commons
The genetic similarity between one variety of common garden snails found in Ireland and the Pyrenees, in Southern Europe, may be explained by human...

Science Explains Why You Forgot To Take Out The Trash

A familiar voice is usually recognized between other voices, but as we age, maybe we can select not to hear them
It's often nice to hear a familiar voice, but sometimes we're also guilty of tuning out wives, husbands, parents and even some friends. It turns out...

Chaos, Not Order, Spark Creativity

Being neat and tidy has always been associated with order, tradition and general good sense. But being a slob may have a worse reputation than it...

Even in the Brain, Practice Makes Perfect

Extensively practicing a given motor skill reduces metabolic activity in the cerebral cortex responsible for managing that skill
As any athlete or musician can attest, practicing makes a difficult task easier. In fact, repeating an activity can take us to a point where we a no...

Celestial Music, at your fingertips

Crab Nebula, Wikipedia.
In the renaissance an scholar was considered educated only after mastering the so-called "quadrivium", which consisted of four subjects: arithmetic,...

Social networking makes lemurs smarter

Ringed-tail lemurs
Human evolution has been marked by two major milestones: an increase in brain size and the development of social groups. Many scientists have assumed...

The Mind Can Fly a Helicopter

Our mind can control an external device
A helicopter is a rather complicated craft to fly--it doesn't really glide, and moves by controlling the pitch and power of its rotor blades. Imagine...

Advertise with The Munich Eye
Allianz - Munich financial services Web Site Optimisation