104 LEECHES 



age and dying soon afterwards, but Erpohdella octoculata and 

 Glossiphonia complanata are longer lived. Most of the leeches of 

 these two species breed at 1 year of age, they all breed at 2 years and 

 after that most of them die. Those that survive beyond this time 

 are probably the ones that failed to reach maturity in the first year 

 of life. Helohdella stagnalis has a life history which is different 

 again, some ofthe leeches passing through two generations in lyear. 

 Overwintering leeches breed in spring and die soon afterwards; 

 some of the spring brood grow to maturity that summer, breed and 

 die, but the remainder overwinter to breed the following spring. 

 The proportion reaching maturity in less than 1 year seems to 

 depend on the weather (Mann, 1957b). 



2. Fertilization 



Leeches are protandrous hermaphrodites and cross fertilization 

 is the general rule. The Hirudidae have an eversible penis and 

 at copulation this is inserted into the vagina of another leech. If 

 the animals take up a head-to-tail position reciprocal fertilization 

 is possible, but this is by no means general and unilateral action is 



Fig. 54. Hirudinaria granulosa copulating. From Bhatia, 1941. 



probably more usual. Leslie (1951) described a simple courtship 

 display by the land leech Haemadipsa. It involved tapping (with 

 their anterior suckers) the leaf on which they were sitting and 

 entwining the anterior ends of their bodies in various ways before 

 copulating. Leeches of the families Erpobdellidae, Glossiphoniidae 

 and Piscicolidae lack the eversible penis and transfer the sperm 



