glochidia

Larvae, called glochidia, are released from the female mussel and complete their larval development by attaching to the gills or fins of aquatic vertebrates, typically fish, as obligate parasites.

Freshwater mussels in North America - factors affecting their endangerment and extinction 2009

Temperature rise will also play a role in the timing of spawning, causing females to release glochidia into the water column earlier, thus uncoupling the timing of mussel and fish reproduction cycles, especially in anadromous fish.

Freshwater mussels in North America - factors affecting their endangerment and extinction 2009

Although elevated surface water temperature has been shown to enhance recruitment (post-settlement survival) and increase the growth rates of glochidia, this is primarily observed in instances where mussels have a chance to acclimate themselves to the temperature, however, extreme thermal events may be detrimental to their survival.

Freshwater mussels in North America - factors affecting their endangerment and extinction 2009

The high fecundity of mussels increases the likelihood for at least some glochidia finding a host.

Freshwater mussels in North America - factors affecting their endangerment and extinction 2009

Non-hooked glochidia: do not have large hooks, but their inner shell margins have fine sharp spines.

Mollusca 2007

After feeding for 2 to 36 hours, the glochidia encyst.

Mollusca 2007

Hooked glochidia: are found only in species of the subfamily Anodontina.

Mollusca 2007

When a fish dives in for a meal, the "worm" retracts and a cloud of glochidia is released.

Mollusca 2007

Axehead glochidia: are found only in the genus Proptera and have a left and right shell lobe that flares outward giving the appearance of an axe head.

Mollusca 2007

These chains of glochidia look amazingly like worms that many fish find tasty.

Mollusca 2007