Saturday, July 16, 2011

Invaders on the tree trunk

Herennia with a male at left
Why did the fly fly
because the spider spied 'er

On a visit to the Kaveri riverside, I spotted this spider on the trunk of a Terminalia arjuna. It was only muxh later that I learnt about its identity. It seems to be Herennia possibly H. multipuncta. Like many successful creatures it has been termed as an "invasive", apparently because it has been found rather unexpectedly on many islands across Asia. It seemed rather odd, for I had never seen it before and one generally expects "invasives" to be more ubiquitous. Anyway, "invasives" appear to be one of those buzzwords invented by scientists to get funding behind their work and for a recent turn of events on the "science and politics" behind the term - do check out this essay. Anyway, the female of our spider is the large one with a strange disc with pores while the tiny orange one at the left is the male. It takes a while to realize that it is an orb-weaver and are in the same family as the Nephila wood spiders, the orb is actually placed close to the tree trunk in tight circle and presumably targets small bark living insects. The orb itself is constructed so that it does not touch the trunk, but this was not readily apparent. The male at the left appears to be unmated - as apparently those that mate, sever their pedipalps - blocking the female genital opening to ensure paternity. These eunuch males cannot mate again but continue to stay beside the females.
Further reading

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