Saturday, March 28, 2020

Only spurious resemblance—or is it natural mimicry


Above (top) is a rendering of an especially odd-looking insect, native to the Amazon, the Latin name of which is Fulgora laternaria. A so-called planthopper, it is more commonly known as the lantern fly, peanut bug, and alligator bug. It is frequently cited as an example of natural mimicry, perhaps as Batesian mimicry, in which a harmless species is in part protected from predators because it resembles a harmful species.

It is widely claimed, for example, that monarch butterflies are unpalatable to birds, which learn to avoid them. As a consequence, there are other monarch look-alikes, non-toxic and otherwise harmless, that are also avoided by birds. American artist Abbott Handerson Thayer, who collaborated with his artist-naturalist son, Gerald Thayer, in 1909 on a major book about animal coloration, was doubtful of Batesian mimicry. Although the concept is mentioned more than thirty times in the Thayers’ 260-page opus, their references differ considerably from the meaning that Bates had intended. Thayer’s skepticism about the link between unpalatability and mimicry was sufficient that he took a trip to the West Indies, where various mimics of monarchs are found. “He actually tasted them,” recalled his daughter Gladys, who traveled with him, “and could find no difference in the flavor.”

In the case of the lantern fly or peanut bug, it is thought to make use of mimetic resemblance in two ways: One is that, if startled, it responds by unfurling its bottom wings, revealing large, conspicuous eyespots or ocelli (as seen in the top illustration), and emitting a “foul-smelling substance.” The other, less convincing way in which it may benefit from mimicry is found in the puzzling shape of its snout (as shown in the photograph above), which certainly looks like a peanut, but which some scientists also claim might easily be mistaken for the head of a snake, a lizard, or even an alligator.

Examples like these inevitably bring up the question of which instances of “mimicry” are not mimicry at all, but are merely the result of projections on the part of the viewer, such as occurs in our sightings of Rohrschach ink-blots, images in the clouds, or pictures of Christ on tortillas. Arthur Koestler spoke of this in The Act of Creation (pp. 375-376)—

Pliny recounted the anecdote of an artist who tried in vain to paint the foam at a dog’s mouth until, in exasperation, he threw a spongeful of paint at the canvas—and there was the foam. The story reappears in Leonardo’s Treatise on Paintings—where he makes “our Botticelli” say that if you just throw a sponge at a wall, it will “leave a blot where one sees a fine landscape.”