Experiments using walkmans underwater have revealed for the first time that young marine animals can use sound to choose the best home.
A team at the University of Auckland played crab megalopae (the post-larval stage before adulthood, shown above) recordings from 6 of their common reef habitats and measured the time it took them to metamorphose (a sign of crab happiness) in the absence of any other sensory information.
The faster the metamorphosis, the happier the crab and remarkably the little nippers were happier listening to some sounds than others. In fact, the difference in crab happiness between the best and worst habitat sound was as much as 47%.
Amazingly, the ‘best’ sounds corresponded to the safest habitats in the wild, showing that the tiny crustaceans can judge a potential home by sound alone.
The results, published in proceedings of the royal society also show for the first time that sound can actually induce metamorphosis in a process termed morphogenesis.
So what do baby crabs like to listen to?
It turns out they like rock music! The sounds from a rocky environment contain just the right frequencies to entice the megalopae into metamorphosis. The researchers think that these frequencies are produced by other neighbouring animals living in the desirable area such as snapping shrimp and sea urchins. The presence of these species signposts the sheltered, food-rich environment that the megalopae desire.
Finding a safe home is crucial to reef-dwelling larvae if they’re to successfully mature into adults and avoid being eaten along the way.
It is widely known that animals are able to distinguish areas of the sea using chemical and visual signals. However, these are sometimes only reliable over short distances and can be influenced by sea currents.
Sound on the other hand can travel long distances and provides useful biological information no matter what the climate. The current findings in juvenile crabs could therefore be applicable to a large number of developing marine animals.
However, in light of this new discovery, it is possible that the underwater noise pollution produced by humans could impact upon the settlement and survival of marine species.