The Flamingo’s Smile by Stephen Jay Gould Read Free Book Online

male approaches slowly and cautiously, finally cutting the female’s web at several strategic points, thereby reducing her routes of escape or attack. The male often throws several lines of silk about the female, called, inevitably I suppose, the “bridal veil.” They are not strong, and the larger female could surely break them, but she generally does not, and copulation, as they like to say in the technical literature, “then ensues.” The male, blessed with paired organs for transferring sperm, inserts one palp, then, if not yet attacked by the female, the other. Hungry females may then gobble up their mates, completing the double-entendre of a consummation devoutly to be wished.
      The argument for direct selection of sexual cannibalism rests upon two intriguing phenomena of courtship. First, the tip of the male’s palp usually breaks off during copulation and remains behind in the female. Males, thus rendered incomplete, may not be able to mate again; if so, they have become Darwinian ciphers, ripe for removal. (An interesting speculation identifies this broken tip as a “mating plug” selected to prevent the entry of any subsequent male’s sperm. Such natural post factum chastity belts are common, and of diverse construction, in the world of insects and would make a fine subject for a future essay on the same issue of why sexual selection identifies our evolutionary world as Darwinian.) Second, males show far less avidity and caution in scramming after the fact than they did in approaching before. K. Ross and R.L. Smith write (see bibliography): “Males that succeeded in insemination lingered in the vicinity of their mates or wandered leisurely away. This was in marked contrast with the initial cautious approach and escape strategies characteristic of males prior to insemination.”
Females of the desert scorpion Paruroctonus mesaensis are extremely rapacious and will eat anything small enough that they can detect. “Any moving object in the proper size range is attacked without apparent discrimination” (G.A. Polis and R.D. Farley, see bibliography). Since males are smaller than females, they become prime targets and are consumed with avidity. This indiscriminate rapacity presents quite a problem for mating, which, as usual, requires some spatial intimacy. Males have therefore evolved an elaborate courtship ritual, in part to suppress the female’s ordinary appetite.
      The male initiates a series of grasping and kneading movements with his chelicerae (minor claws), then grabs the female’s chela (major claw) with his own and performs the celebrated promenade à deux , a reciprocal and symmetrical “dance,” pretty as anything you’ll see at Arthur Murray’s. These scorpions do not inseminate females directly by inserting a penis, but rather deposit a spermatophore (a packet of sperm) that the female must then place into her body. Thus, the male leads the female in the promenade until he finds an appropriate spot. He deposits the spermatophore, usually on a stick or twig, then bats or even stings her, disengages, and runs for his life. If good fortune smiles, the female will let him go and pay proper attention to inserting his spermatophore. But, in two cases out of more than twenty, Polis and Farley found the female munching away on her mate while his spermatophore remained on a nearby stick, presumably for later ingestion through a different aperture.
    What evidence, then, do these cases provide for selection of sexual cannibalism among males? Do males, for the sake of their genetic continuity, actively elicit (or even passively submit to) the care and feeding of their fertilized eggs with their own bodies? I find little persuasive evidence for such a phenomenon in these cases, and I wonder if it exists at all—although the argument would provide an excellent illustration of a curiosity that makes little sense unless the evolutionary world works for reproductive success of