Fish Radio
July 8, 2014

 Crabs can hear                               

Snow crab statocyst at base of antennae. Hairs respond to sound. Credit:

Snow crab statocyst at base of antennae. Hairs respond to sound.


This is Fish Radio. I’m Laine Welch — Crabs freak out over certain noises. First ever findings after this –

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Creepy soundtracks of noises made by predators had crabs running for shelter and proved, for the first time, that the animals can hear. Marine acoustic experts at Boston’s Northeastern University made the discovery in lab tests on 200 mud crabs during a two year study. When they piped in certain noises, the crabs didn’t dare venture out to eat juicy clams placed in their tanks.

Their skittishness lasted for several hours. The scientists said the crabs hear through a small sac at the base of their antennae. Might it be the same for Alaska crab?

 I would not be surprised. The general functioning of the antenna is to sense movement and in some cases, sense chemical changes. So I wouldn’t be surprised if it was the same because that is the general function of that structure.   

Bob Foy is director of NOAA Fisheries top crab lab at Kodiak. He says he found the crab hearing study fascinating.

 Sound is just a pressure wave so the fact that they can hear the sound, I’m not surprised at all. The interesting fact is how they are reacting to a predator or to another organism being there, and being able to measure that stress that the animal is undergoing at the same time is very interesting. 

 Other studies showed that ship sounds affect foraging behavior of shore crabs. All of the hearing findings can be important for crab scientists and managers –

 Absolutely – on a couple of fronts. The crab communication is very important. Trying to understand the behavior of the crab – how do the males and females find each other. Crabs don’t broadcast spawn like a fish does; they have to find each other in a large ocean. Very often you have males and females migrating in different directions, as is the case for both snow crab and red king crab. So potentially that helps with communication, and knowing more about their behaviors at that level would be critical for understanding how these animals are moving throughout their environment. Another thing is when you think about environmental impacts, like the effects of ship noise, or of oil drilling – how the impacts of sonar and other kinds of sensory tools may or may not affect these animals. And knowing that they do have this sensitivity helps us think about how we might test for these things. 10

 Foy says he hopes the crab hearing studies continue –

 Absolutely. If you had asked me can crabs hear prior to this, I probably would have said they probably have a way of detecting sound. But seeing how they are detecting it and then how they are responding to noises and other predators is very intriguing in terms of how we might be able to use this in the future.   

The story first appeared in the Washington Post.

Fish Radio is also brought to you by Ocean Beauty Seafoods. Ocean Beauty has contributed over 10 million meals to the U.S. Food Bank network, and is committed to ending hunger in America.   In Kodiak, I’m Laine Welch.