Anisopary in compost earthworm reproductive strategies (Oligochaeta)

Individual differences in the number of hatchlings and cocoons produced by Eisenia fetida have been recorded. We propose to call this phenomenon anisopary — unequal reproduction (an — not, iso — the same, parere — to produce). The reproduction of individual partners from pairs of E. fetida were studied. The earthworms were mated for 72 h and then separated. In 85% of all matings one partner produced on average twice as many hatchlings as the other — in the remaining 15% the partners produced on average equal numbers of hatchlings. The biomass changes of the earthworm partners corresponded with the apparent reproductive functioning of the worms. We suggest that there are sperm donors — low producing (hypopary) and sperm receivers — high producing (hyperpary) earthworms.