London, July 29 (ANI): In a new research, scientists have shown that the tactic of insects to squirt toxic blood out of gaps in their body to avoid being eaten by predators really does work.
Armoured ground crickets (Acanthoplus discoidalis) are fat, flightless insects that live in the African bush across Namibia, Botswana and South Africa.
They are relatively large, growing up to 5cm long, have sharp spines across their thorax and legs and a pair of strong biting jaws.
To become unpalatable, the insects squirt toxic blood out of gaps in their body and make themselves sick by throwing up food they've just eaten.
A few insect species including beetles and katydids actively bleed when attacked, but the benefits of taking such extreme measures were not clear.
Now, according to a report by BBC News, scientists have shown the tactic really does work to deter predators such as lizards.
"When I was moving them to larger quarters I was thinking about how they would grip a branch and when I pulled I would inevitably feel the squirt of the blood jetting out from under their legs," entomologist Bill Bateman of the University of Pretoria in South Africa told the BBC.
"This is a recognised defence mechanism and has been mentioned in other invertebrates, but no one had published on what exactly makes them do it or whether it actually is effective against predators," he said.
So, Bateman and colleague Trish Fleming of Murdoch University in Western Australia tested the defensive abilities of the armoured ground crickets.
First, he mimicked attacks by predators by grabbing the insects from the side or above with tweezers.
The crickets responded differently depending on the mode of attack.
When attacked from the side, the crickets stridulated and tried to bite their attacker. About two-thirds of the time, they also squirted out acrid-smelling haemolymph from seams in the connective tissue of their legs and from just behind the head.
Attacked from above, a direction in which they could not bite, the crickets oozed toxic blood almost nine times out of ten.
Sometimes, the crickets squirted their own blood up to 6cm.
"The blood is pale green and rather acrid smelling. I couldn't bring myself to actually taste it fresh but it leaves an acidy, tobacco-like taste on your fingers if you do not wash it off," said Bateman.
According to Bateman, this proves how sophisticated the crickets' defence responses are. (ANI)