Glochidia


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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Glochidia

 

the parasitic larvae of freshwater bottom mollusks—Lamellibranchia—of the family Unionidae. Glochidia have bivalve triangular shells, which close by means of single, contracting muscles. The edge of each valve usually has a serrated spine. The foot is undeveloped and is equipped with a long adhesive byssal thread—the lasso. The intestines are reduced. In the early stages of their development glochidia enter the, gills of a host specimen, where they lay eggs. In the spring, with the aid of the spines and the lasso, they attach themselves to the gills and skin of fish. In this manner glochidia spread through a body of water and move against river currents. After metamorphosis, the mollusk drops to the bottom. Glochidia cause no particular damage to fish.

V. A. SVESHNIKOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Caption: Golden riffleshell "glochidia", or tiny immature young, reveal themselves with the aid of a microscope.
Transportation of glochidia by a host fish enables them to reach the upper regions of a river or stream, and an even wider distribution may occur if birds or other animals feed on the host fish.
A museum voucher of this species from the Calamus Reservoir in the Loup Basin probably represents a recent colonization via glochidia infected fish.
Although the underlying basis for host specificity and host resistance to glochidia are largely unknown, local tissue reactions of the host are likely important in mediating these responses (Arey, 1921; Meyers and Millemann, 1977; Fustish and Millemann, 1978; Meyers et al., 1980; Rogers-Lowery and Dimock, 2006).
Each female will produce around three million glochidia each year but even in ideal conditions only 0.01% will survive.
The odds against any one individual glochidium surviving are extremely large--thousands or millions of glochidia may be produced, but the vast majority never encounter a fish.
Rhizosperma is characterized by the presence of papillae all over the vegetative body, the presence of nine megaspore floats, and the presence of simple glochidia; whereas sect.
Freshwater mussels (Unionidiae or unionids) are dependent on a host fish for dispersal during an early parasitic life stage known as a glochidia. Most unionid species are dioecious and can exhibit sexual dimorphism in which females often develop a large mantle tissue flap to attract a host fish.
The 24-h CF LC50 estimates for glochidia of multiple species vary widely, ranging from 113 to 3,257 mg/L (Bringolf et al.