At first, the adult nematodes of the species Pristionchus pacificus don’t seem to be particularly out of the ordinary. Like many other nematode species, they’re small (about 1 mm long), live in the soil, and eat bacteria and fungi. But a closer look at their entire life cycle reveals that the worms spend their youth mooching off another animal.
Adult worms are self-fertilizing hermaphrodites – that is, each worm has both male and female sex organs, and is (ahem) perfectly capable of getting itself pregnant. Worms lay their eggs in the soil, where they hatch, but the larval worms don’t stay there for long. Instead of molting and growing in soil, larval P. pacificus start looking for a beetle to ride (their particular host is the Oriental beetle Exomala orientalis) by cuing in on their sex pheromones. When a larval worm finds an appropriate beetle, it bores into its cuticle. Then it goes dormant and waits for the insect to die. When the beetle’s rotting corpse becomes home to a veritable smorgasborg of bacteria and fungi, the worm comes out of dormancy and feasts until it can make the final molt into adulthood and move out of its childhood home.
Photo: Dr. Ralf Sommer, Max Planck Institute for Developmental Biology
Comments