Reproductive Behaviour and Parental Care of Helobdella striata (Hirudinea,Glossiphoniidae): a Leech that Feeds its Young

The leech Helobdella striata Kutschera (1985) is a protandrous hermaphrodite. It copulates by hypodermic injection: a spermatophore is attached to the skin of the partner and sperm injected through it. During their male phase, the leeches copulate repeatedly and with different partners. In the female phase, 3 to 7 cocoons, each containing 2 to 20 eggs, are produced from the female gonopore and attached to the ventral side of the parent. The larvae which hatch from these eggs cling to the ventral side of the parent. After they have used up their yolk supply and have developed into juvenile leeches they remain attached to the parent for a further three weeks. Helobdella striata capture Tubifex worms and give them to the young they carry. This access to food allows the juveniles to grow from a size of 1 mm to 6 mm length while being carried and protected by the parent. H. striata reared in isolation produce young; at present it is not known whether they reproduce by parthenogenesis or by self-fertilization. The probable phylogenetic development of parental care patterns in the Hirudinea is reviewed.