Wednesday, 23 September 2009
I've been away in the West Country, terrorising relatives with my Mum on her late summer holiday. A highlight was Bristol Zoo where my two young cousins Robbie and Alfie took these excellent pics in the Butterfly House while Mum and I admired the Davidia or Pocket Handkerchief Tree (which has an offspring in Leeds, grown from a nut collected in Bristol Zoo about 15 years ago). The first butterfly is a 'glasswing' whose camouflage involves being transparent. The CD-like thing on which it is perchd is a nectar dispenser; disgracefully spoilt, these captive butterflies. Robbie and Alfie's family and I had deep discussions about whether it would be possible for an entire moth to become transparent like this; or indeed an entire human being, as in H G Wells' The Invisible Man. We couldn't see why not, although 'glass humans' might look rather offputting after meals.
Needless to say, there is some interesting science about this online, for example on http://scienceray.com/biology/zoology/almost-invisible-the-incredible-glasswing-butterfly/. From this, I also gleaned the fact that Glasswings are from South America and have the unusual and satisfactory scientific name of Greta oto and the even better Spanish one of espejitos, or 'little mirrors'. The middle pic shows a butterfly which seems to have latched on to op art or dazzle camouflage as a way of changing its outline. I'm rather proud of my detective powers; I guessed at its name, put 'zebra butterfly' into Google and bingo! It has another defence mechanism: the ability to make a sinister creaking sound with its body when disturbed. The last example, below, is an Owl Butterfly, like the other two a native of the Americas. I know it's blurred, but to me that suggests rather well the way its deterrent camouflage (rather than hiding camouflage) might appear in action to a predatory bird. Off-putting.