Female Spiders Judge Mates by Their Gift Wrap
|A Paratrechalea ornata male carries a white wrapped gift to lure a mate.|
Credit: Mariana Trillo
Trillo and colleagues conducted experiments with semi-aquatic Paratrechalea ornate spiders collected from the Santa Lucia River in Uruguay. During one test, the scientists painted the mouth parts of some of the male spiders white. (The spiders carry their nuptial gifts in their mouth parts.) The females paid more attention to the male spiders with painted mouths. They also mated with the painted males earlier and more often than the males without paint.
The scientists think their results suggest the white coloring of the silk is the main draw for female spiders. Because this species is most active during sunset and at night, white silk is to see over long distances. What's more, males in better physical shape produced whiter gifts because they used more silk in their wrapping, while the poor wrapping job of less healthy males resulted in a duller package. This means the color of the gifts could be a reflection of the male's body condition, which could the females judge their suitors, the scientists say in the journal Naturwissenschaften.