Videos
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Some freshwater mussels have evolved unique mantle modifications and behaviors to lure host fish to be parasitized. A few can be seen below.
Pocketbook (Lampsilis cardium) - mantle flapping behavior (different population) |
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Ridged Pocketbook (Lampsilis ovata) - mantle flapping behavior |
Pink Mucket |
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Rayed Bean (Villosa fabalis) - mantle display |
Lilliput (Toxolasma parvum) - mantle display Unlike most populations, those from Lake Erie have mantle flaps rather than caruncles. |
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Northern Riffleshell (Epioblasma torulosa rangiana)
Spermatozeugmata ("sperm balls"). Freshwater mussel males release sperm in structures called spermatozeugmata. Resembling a colony of Volvox, sperm are embedded head-first in a double-layered hollow sphere. The "sperm balls" seen here are from the Giant Floater, Pyganodon grandis.
Although sperm are released as spermatozeugmata it is obvious that they cannot fertilize eggs in this state. How and when spermatozeugmata are dissociated into individual sperm was unknown. In a simple experiment, shown here, fluid was removed from a female's intra-branchial space and added to spermatozeugmata. The result is dramatic. In the "Dissocation" video, once the camera stops moving, note a wave of dissociation beginning in the upper left (where the fluid was added). Clearly, when spermatozeugmata contact fluid from the female's gills they dissociate and are available to fertilize eggs. We are now isolating the component of the fluid responsible for the dissociation. The mechanism of dissociation remains unknown.
Lymnaea stagnalis just before hatching | Lymnaea stagnalis newly hatched |