The life history of the gastropod ThyonicolaAmericana Tikasingh, endoparasitic in a seasonally eviscerating holothurian host

The endoparasitic gastropod Thyonicola americana Tikasingh attaches to the intestine of the dendrochirote holothurian Eupentacta quinquesemita (Selenka ). Evisceration by E. quinquesemita is a seasonal
event occurring in the autumn and as a result of their attachment to the viscera, T. americana is
annually expelled from its host . The effect of evisceration on the life cycle of T. americana was
investigated. Reproduction of the parasite is continuous, but the number of specimens at an advanced
reproductive state was highest in summer and decreased coincident with seasonal evisceration.