May 13, 2017
Decorator Crabs Make High Fashion at Low Tide | Deep LookWhen you live by the seashore, one day you're in, the next day you're lunch. So these crabs don the latest in seaweed outerwear and anemone accessories to blend in.
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As fans of the hit TV show Project Runway know, in fashion one day you’re in, and the next day you’re out. Nowhere is this truer than in the animal kingdom. One minute you’re a crab minding your own business in a tide pool, and the next, you’re a seagull’s snack.
Unless you’re a decorator crab, that is, and you use this season’s seaweed to save your life.
There are nearly 700 species of decorator crabs around the world – about a dozen of them in California, where they live in tide pools and kelp forests. They camouflage by decorating their heads, or their entire bodies depending on the species, with pieces of seaweed, anemones or other materials around them, which they attach securely to a natural Velcro that grows right on their bodies.
“It’s not a glue or anything; they have these hooked hairs all over their shells,” said biologist Jay Stachowicz, who studies decorator crabs at the University of California, Davis. “Through microscope photography we can see that it looks just like Velcro, except probably even better, even more hooked.”
These golden-colored hairs are thick and curled to form long rows. Some species of decorator crabs have these rows of hooked hairs only on their heads; others, on their entire bodies.
At his lab at UC Davis’ Bodega Marine Lab in Bodega Bay, Stachowicz collects crabs off the coast, places them in tanks, gives them some seaweed and watches them go to work.
The process is more exciting than watching Project Runway contestants create their confections, if you consider that the crabs are making it work with much more simple tools than the designers. And the stakes are much higher.
--- How does a decorator crab camouflage?
A pink Cryptic kelp crab, for example, cuts a piece of purple seaweed with one of its claws.
Then the crab holds the piece of seaweed above its head, the only part of its body where it has hooked hairs. It moves the piece of seaweed back and forth, until it’s tightly wedged inside the hooks. Then it repeats the process. The result is a “hat” of bushy seaweed that protrudes beyond its head.
With the seaweed, the crab is concealing two of its four antennae, short protuberances near its mouth. These antennae are constantly aflutter. The crab uses them to smell, and they could call the attention of predators even when the crab remains still. By hiding the movement of the antennae, the seaweed visor protects the crab from birds pecking around in the tide pools and aquatic predators like fish and octopuses.
--- What is Tim Gunn’s most famous quote?
The beloved advisor to contestants of Project Runway has many memorable phrases. But we’re pretty confident that one of his best-known sayings is “Make it work!”
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Jay Stachowicz Lab at the University of California, Davis:
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