THE KINETIC CONGLUTINATE OF THE CREEPER FRESHWATER MUSSEL, STROPHITUS UNDULATUS (SAY, 1817).
The conglutinate of the creeper, Strophitus undulaus (Say, 1817) (Unionoidea: Unionidae), was studied with light and scanning electron microscopy. This conglutinate has a very simple structure consisting of a homogeneous, spongy material containing the glochidia. Each glochidium is contained within its egg membrane and is tethered to this membrane by the glochidial thread. Within the female's marsupium, the glochidia are contained within the conglutinate. When they are expelled to the water the glochidia emerge through pores to the outside and become infective. The mechanism for pushing the glochidia out of the conglutinate is osmotic. The marsupium apparently bathes the conglutinates in a hypertonic solution. When conglutinates are expelled to the surrounding hypotonic water, the spongy material of the conglutinate swells, pushing the glochidia out through the pores. Unlike other conglutinates studied, that of S. undulatus displays a brief period of innate motion which may be adaptive in attracting a suitable host.
Watters
G. T.
GT
Department of Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, OH 43212, USA.