Why It Matters When Species Go Extinct
Extinctions of Small Species Matter, Too!
The Polar Bear (Source: https://en.wikipedia.org/wiki/Polar_bear)
While the losses of large, iconic species like the wolf, tiger, rhino, and polar bear may make for more stimulating news stories than the disappearance of moths or mussels, even small species can affect ecosystems in significant ways.
The Mussel
The freshwater pearl mussel (Margaritifera margaritifera) is an endangered species of freshwater mussel, an aquatic bivalve mollusc in the family Margaritiferidae. Although the name "freshwater pearl mussel" is often used for this species, other freshwater mussel species can also create pearls and some can also be used as a source of mother of pearl. In fact, most cultured pearls today come from Hyriopsis species in Asia, or Amblema species in North America, both members of the related family Unionidae; pearls are also found within species in the genus Unio.
The exterior of the shell of Margaritifera margaritifera
The interior of the shell of Margaritifera margaritifera has thick nacre (the inner mother of pearl layer of the shell). This species is capable of making fine-quality pearls, and was historically exploited in the search for pearls from wild sources. In recent times, the Russian malacologist Valeriy Zyuganov received worldwide reputation after he discovered that the pearl mussel exhibited negligible senescenceand he determined that it had a maximum lifespan of 210–250 years. The data of V.V. Zyuganov have been confirmed by Finnish malacologists and gained general acceptance.
Consider the meager freshwater mussel: There are nearly 300 species of mussel in North American river and lakes, and most of them are threatened. How does this affect the water we all depend on?
"Mussels play an important role in the aquatic ecosystem," explains the U.S. Fish and Wildlife Service. "Many different kinds of wildlife eat mussels, including raccoon, otters, herons and egrets. Mussels filter water for food and thus are a purification system. They are usually present in groups called beds. Beds of mussels may range in size from smaller than a square foot to many acres; these mussel beds can be a hard 'cobble' on the lake, river, or stream bottom which supports other species of fish, aquatic insects and worms."
In their absence, these dependent species settle elsewhere, lower the available food source for their predators and in turn causing those predators to leave the area. Like the gray wolf, even the small mussel's disappearance acts like a domino, toppling the entire ecosystem one related species at a time.