Male mantis shrimps form rap groups to woo females and scare away intruders, according to research published in a recent issue of the journal Aquatic Biology.
Erica Staaterman and colleagues used a coupled audio–video system, a hydrophone array, and an autonomous recording unit to demonstrate that the mantis shrimp Hemisquilla californiensis, a species living in burrows off the coast of California and Mexico, produces low frequency 'rumbles' through vibrations produced by muscles under the carapace. Based on experiments on captive individuals, it seems that only male mantis shrimps made this sound.
The authors characterised the rumbles made in field recordings, and compared them to similar sounds made by captive animals in the aquarium. They also examined the rumbles in a temporal context, recording the rumbles for almost eight days continuously, and then analysing the data to test whether patterns in mantis shrimp acoustic activity matched previously documented behavioural activity.
The authors found that the rumbles made by the mantis shrimp in their natural habitat were more variable and occurred in rhythmic groups (meaning that more than more than two shrimp were rumbling in synchrony), compared to those made by captive shrimp. They also found that the rumbles were most frequently made during dawn and dusk, when the shrimp were most likely looking for food or guarding their burrows.
The authors hypothesise that the rumbling could be used to warn away intruders or even be used to woo females.
For more information, see the paper: Staaterman, ER, CW Clark, AJ Gallagher, MS deVries, T Claverie and SN Patek (2011) Rumbling in the benthos: acoustic ecology of the California mantis shrimp Hemisquilla californiensis. Aquatic Biology 13, pp. 97–105.
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