Body electric
Skates and sharks have specialized electrosensory organs that detect weak electric fields and communicate the information to their central nervous systems. In this issue, David Julius and his colleagues analyse sensory cells within these organs and show that although both skates and sharks use similar low-threshold voltage-gated calcium channels to start the cellular process, they each use distinct potassium channels to modulate this activity. The authors found that the potassium channels in the chain catshark (Scyliorhinus retifer) support large repetitive membrane voltage spiking in response to electrical stimuli, but those in the little skate (Leucoraja erinacea, pictured on the cover) produce smaller, tunable oscillations. The researchers suggest that as a result sharks use their electrosensory capabilities primarily as an aid in predation whereas skates also use them to communicate with one another.