Extraordinary Reproductive Strategy in Freshwater Bivalves: Prey Mimicry toFacilitate Larval Dispersal

摘要

Females of the North American freshwater bivalve Lampsilis perovalis releasetheir larvae, which are obligate parasites on fish, in a discrete mass (superconglutinate) resembling a small fish in shape and coloration. After release, the mass remains tethered to the female by a long, transparent, mucous strand and, in stream currents, displays a darting motion that further mimics a small fish. Release of superconglutinates was observed in March and April at water temperatures of 14-17 degrees C. However, superconglutinates detached from the parent mussel were observed from March to June at water temperatures of 11-26 degrees C, indicating that release may occur into the summer. The superconglutinate lure may function to attract a predaceous fish to ingest the mass, ensuring that the larvae are exposed to a suitable host. This reproductive strategy was confirmed recently to occur in a congener, L. subangulata and is suspected to occur in another congener, L. australis.