Scientists discover deadly secret of predator’s traps
ANTLIONS, one of the most nightmarish insect predators, perform a constructional “conjuring trick” to build their deadly pit traps, Bristol scientists have discovered.
Experiments showed how they
employ a super-efficient spiral digging technique to separate and remove large sand grains.
The final cone-shaped trap is lined with unstable small grains which immediately give way under the feet of any small creature which strays into it.
Like something from a horror movie, the antlion lies in wait at the bottom of the trap, ready to grab the prey in hook-like mandibles and drain its bodily fluids.
To study how antlions build their traps, scientists filled tubs with beach sand containing a mixture of large and small grains and filmed the insects – technically insect larvae – at work.
They were surprised by the extraordinary ability of antlions to eliminate the large grains.
Prof Nigel Franks, from the University of Bristol, said: “It is almost like a conjuring trick – many more large grains are ejected than seems possible. One answer is that the antlion is ‘interrogating’ much more sand to find and eject large grains than just the volume of sand that has to be removed to form the final pit.”
The team used computer simulations to learn more of how antlions methodically dig in spiral patterns and set off miniature avalanches.
Prof Franks added: “This technique is a superbly efficient timesaving method that literally enables antlions to plough through a large volume of sand, such that the small avalanches they create cause large sand grains differentially to cascade to the bottom of the construction trench, where they can be preferentially ejected during pit construction.”
Lining the pit traps with fine sand grains makes them extremely prone to avalanches.
Prof Franks said: “Any prey that ventures into the pit will ride an avalanche down to the deadly antlion at the bottom of the pit. Such pits are an intriguing example of the ever-present force of natural selection that shapes biology.”