Electricity seems to be mainly an animal invention. Animals generate it for internal use — crucially in their nerves. Many fish deploy it externally for navigation, and even as a weapon. But plants, which have no nerves, also generate detectable potentials. Tomato plants may even propagate their internal ‘wound response’ electrically. And while many plants release chemicals which affect others of their species — to prevent local overcrowding, or to ‘warn’ neighbours of an insect attack — claims have also been made that they can signal electrically.

If so, says Daedalus, the place to look for it is in the sea. It is only the conductivity of the water which allows electric fish to deploy their shocking powers. Seaweeds, like all plants, certainly defend themselves against herbivores. These defences have hitherto been taken as chemical — polyphenols, haloterpenoids and so on, to discourage grazing fish and sea-urchins. But maybe some plants, starting from a fairly feeble electrocommunication ability, have developed it into an effective electrical defence? Intrepid DREADCO botanists with volt-meters and rubber gloves are now trawling the ranks of the seaweeds in search of such powers.

As a first step, they are studying the plant communities which grow on and around undersea electric cables. A weed which senses electricity, or which uses it for terrain-marking or signalling, might well concentrate near such cables. If such a plant is found, the team will scrutinize its related species, hoping to find a seaweed whose voltaic powers are strong enough to stun, or at least discourage, marine herbivores. Even if only mildly electric plants exist in nature, selective breeding could develop serious performers.

An electric plant, of course, would be a revolutionary discovery. It would be the ultimate natural solar energy converter. Small-scale applications would probably develop first. A little tank of water-weed, with each plant connected to a lead and a common counter-electrode in the water itself, might in an isolated community be an ideal self-maintaining ‘battery’ for a lamp, a radio, a computer, or a mobile telephone. Scale-up to larger ‘power ponds’ could come later. Daedalus even has visions of glass-bottomed ships propelled by the sunlight shining down through the glass onto its weed coating, and vast lagoons of wired-up seaweed feeding power into the grid.