Growing up in Arkansas, in the epicenter of Tornado Alley, a sound has coded on my psyche. When I hear this sound my breathing accelerates, adrenaline levels rise, and a tightness emerges in my gut. The sound of the sacred tornado siren (above), a cultural icon in the South and Midwest, will elicit a physiological response in men, women, and children alike. “Grab tha child’n Ethel! A tornader be right here on us.” In response to ship noise, crabs respond much the same way.
Noises from humans like road and ship traffic, coastal development, sonar, pile driving, rowdy and drunk spring breakers have greatly altered the oceanic soundscape. These foreign noises can stress an animal as it prepares for action like fighting, hiding, or fleeing. After playing recorded ship sounds, the oxygen consumption of shore crabs (Carcinus maenAs) were greater than those experience just ambient noise. In other words the ship noise made the crabs a little more crabby. In some cases respiration was two times greater and on average was 67% higher. And fatter, ahem larger crabs, demonstrated a greater response than smaller crabs. Because larger crabs and animals in general respire more, larger crabs can also consume proportionally greater oxygen when stressed. Crabs repeatedly exposed to ship noise over two weeks eventually demonstrated less and less of stress response. One is that they simply no energy left to respond (I can only get excited once scenario) or simply acclimated to the sound when no threat presented itself (The boy who cried wolf scenario).
No word on what Enya or Barry White songs do to crabs. Although I can attest that when my next door dormmates in college played Led Zeppelin IV on repeat it did elicit a response from me.
Wale MA, Simpson SD, Radford AN. 2013 Size-dependent physiological responses of shore crabs to single and repeated playback of ship noise. Biol Lett 9: 20121194. http://dx.doi.org/10.1098/rsbl.2012.1194