In a battle worthy of gore and grime fetishists, slimy flatworms attack harvestman arachnids with聽gobs of mucus. But the arachnids sometimes fight back by chopping聽the worms in half with armoured leg spikes.
The armoured harvestman () is an eight-legged arachnid, distantly related to spiders. are sometimes known as 鈥渄addy longlegs鈥�, although confusingly so are .
The armoured harvestman has a lot of problems in life. Its predators include birds, toads, lizards, marsupials and even insects such assassin bugs.
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As a result, it has evolved a number of defence mechanisms, says zoologist at the University of S茫o Paulo in Brazil. It has thick armour 鈥� hence its name 鈥� and it can also fake its own death, run away, or pinch attackers with its spiny mouthparts.
In the name of science, Willemart and his colleagues decided to see what kind of fight the arachnids would put up against a Brazilian terrestrial flatworm (). 鈥淪uch battles are happening every night in Brazilian tropical forests,鈥漢e says.
They pitted 32 harvestmen against 32 flatworms in separate battles, all taking place in glass casserole dishes. Willemart says it was like watching a miniature version of .
In all, 22 flatworms attacked. Two succeeded in subduing harvestmen with their slimy mucus, after first striking with their heads.
The worms聽have a聽mouth in the middle of their bodies, which has a throat they can turn inside out. When attacking the harvestmen, they remove the arachnids鈥櫬爉outh parts and front聽legs then聽suck their guts out of the leftover hole.
The harvestmen鈥檚 armour wasn鈥檛 much help against the worms. However, 15 secreted smelly chemicals, causing the worms to retreat 鈥� although the team says they might not work against the harvestmen鈥檚 other enemies, like scorpions and spiders.
Most dramatically, two harvestmen used the spikes on their rear pair of legs to chop the attacking worms in half.
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Surviving a flatworm attack still brought costs for the harvestmen, though. The authors put those arachnids that had been slimed but survived the attack on a running track. They found that they walked significantly less than uninjured harvestmen. Plus, they still had worm slime on them 30 hours later.
Journal of Zoology
