BRISTOL, Conn., Jan. 14 (UPI) -- Pitcher plants switch off their trap for long periods of time -- not because they're tired or feeling merciful (they don't have the capacity for such), but because they're clever (even without a brain).
Scientists at Bristol University in England found that carnivorous pitcher plants turned off their trapping mechanism for up to eight hours a day. But only days free of rain -- dry days.
When the insides of the pitcher plant are wet, the walls of the funnel-like traps are slippery. They're automatic death traps, almost every ant slides down to its ultimate peril.
One would think the combo of a working trap and slippery walls would make for a smorgasbord of ants. But in experiments, Bristol researchers found that pitcher plants kept constantly wet caught fewer large groups of ants.
Ants are cooperative creatures. When one finds food, they return to the colony to share the information with their comrades.
"When they find a pitcher trap full of sweet nectar, they go back to the colony and recruit many more ant workers," Bristol biologist Dr. Ulrike Bauer explained.
Soon, there's a trail of ants from colony to food source. When a pitcher plant's insides are wet, the exploratory ants never get the chance to inform the community of their miraculous find.
"By 'switching off' their traps for part of the day, pitcher plants ensure that scout ants can return safely to the colony and recruit nest-mates to the trap," Bauer said. "Later, when the pitcher becomes wet, these followers get caught in one sweep. What looks like a disadvantage at first sight, turns out to be a clever strategy to exploit the recruitment behavior of social insects."
The pitcher plant study was published this week in the Royal Society journal Proceedings B.