Tuesday, November 30, 2010

The surreal treehoppers

Last week’s Nature highlighted the sculptures of Alfred Keller (1902-1955), and the example, a model of the Brazilian treehopper Bocydium globulare, struck me as one of the weirdest animals I’ve ever seen:



Martin Kemp describes Keller’s work:

Keller was trained as a kunstschmied, an ‘art blacksmith’. From 1930 until his early death he was employed by the Berlin Museum für Naturkunde (Museum of Natural History), painstakingly labouring over his recreations of insects and their larvae. Each took a year to complete. Keller worked first in plasticine, from which he cast a model in plaster. This plaster reference model he then recast in papier maché. Some details he added, cast in wax, with wings and bristles in celluloid and galalith (an early plastic material used in jewellery). Finally he coloured the surfaces, sometimes with additional gilding. The levels of patience and manual control Keller exercised were incredible. His fly, for example, boasts 2,653 bristles.

. . . Keller was a sculptor of monumental one-off portraits. Each model is a masterpiece, with no effort spared. It is difficult to see how such a skilled artisan could survive in today’s museums, with their emphasis on cost analysis. Keller’s exacting models may be things of the past, yet they are far from obsolete. Like the great habitat dioramas, they exercise a magnetic attraction.

The first thing a biologist does on seeing a model like this is think, “This can’t be real,” and resorts to some Googling. Sure enough, it’s a real insect.  Here are two photos:

The second thing one asks is, “What the bloody hell is all that ornamentation on the thorax?” (Note that the “balls” on the antenna-like structure aren’t eyes, but simply spheres of chitin.)  A first guess is that it’s a sexually-selected trait, but those are often limited to males, and these creatures (and the ones below) show the ornaments in both sexes.  Kemp hypothesizes—and this seems quite reasonable—that “the hollow globes, like the remarkable excrescences exhibited by other treehoppers, probably deter predators.”  It would be hard to grab, much less chow down on, a beast with all those spines and excrescences.

Note, though, that the ornament sports many bristles.  If these are sensory bristles, and not just deterrents to predation or irritating spines, then the ornament may have an unknown tactile function.

Membracids, related to cicadas, are in the class Insecta (insects, of course), the order Hemiptera (“true bugs”) and the family Membracidae.  Like aphids, which are also “true bugs,” adult and immature treehoppers feed on plant sap.

For a wonderful panoply of membracid photos, download this pdf file.Here are some of the images, showing that, as Kipling said, “The wildest dreams of Kew are the facts of Khatmandu.” If Dali invented insects, they’d look like these.

The color and shape of this last one makes me suspect that it’s mimicking a wasp:

h/t: Matthew Cobb

See and download the full gallery on posterous

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