Why It Matters When Species Go Extinct

We are surrounded by endangered species every day. Majestic tigers grace posters on bedroom walls, stuffed toy pandas stare blankly from shopping mall shelves; with the click of a button, we can watch the elaborate courtship rituals of whooping cranes and the strategic hunting habits of the Amur leopard on the Discovery Channel. No matter where we look, images and information about the world's rarest animals are readily available, but do we ever stop to think about the effects endangered species have on their environments, what happens after they disappear?

Let's face it, few of us have crossed paths with a real, live endangered species today—one that is teetering on a tightrope of existence, like the Santa Barbara Song Sparrow or the Javan Rhino— much less consider the implications of their loss.

So, does it really matter if an animal goes extinct when we can still watch it on television, even after it's gone? A single species' disappearance can, in fact, make a huge difference on a global scale. Like pieces of yarn in a woven tapestry, the removal of one can start unraveling the whole system.

The Worldwide Web

Before the internet, the "worldwide web" could have referred to the intricate systems of connections between living organisms and their environments. We often call it the food web, although it encompasses many more factors than just diet. The living web, like a tapestry, is held together not by tacks or glue, but by interdependence—one strand stays in place because it is entwined with many others.

The same concept keeps our planet working. Plants and animals (including humans) depend on each other as well as microorganisms, land, water, and climate to keep our entire system alive and well.

Remove one piece, one species, and small changes can lead to a cascade of problems that aren't easy to fix, including more extinctions.

Balance and Biodiversity

Many endangered species are top predators whose numbers are dwindling due to conflicts with humans. We kill predators all over the world because we fear for our own interests, we compete with them for prey and we destroy their habitats to expand our communities and agricultural operations. 

Take for example the effect human intervention had on the gray wolf and the subsequent effects their dwindling population numbers had on its environment and biodiversity.

Before a mass extermination effort in the U.S. that decimated wolf populations in the first half of the 20th century, wolves kept other animals' populations from growing exponentially. They hunted elk, deer, and moose and also killed smaller animals such as coyotes and beavers.

Without wolves to keep other animals' numbers in check, prey populations grew larger. Exploding elk populations in the western United States wiped out so many willows and other riparian plants that songbirds no longer had sufficient food or cover in these areas, threatening their survival and increasing numbers of insects like mosquitoes that the songbirds were meant to control.

"Oregon State University scientists point to the intricacy of the Yellowstone ecosystem," reported EarthSky in 2011. "The wolves prey on the elk, for example, which in turn graze on young aspen and willow trees in Yellowstone, which in their turn provide cover and food for songbirds and other species. As the elks' fear of wolves has increased over the past 15 years, elk 'browse' less—that is, eat fewer twigs, leaves, and shoots from the park's young trees—and that is why, the scientists say, trees and shrubs have begun recovering along some of Yellowstone's streams. These streams are now providing improved habitat for beaver and fish, with more food for birds and bears."

But it's not only large beasts of prey that can impact the ecosystem in their absence, small species can have just as big of an effect.

Extinctions of Small Species Matter, Too

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.

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 cause 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.

Keeping the Web Intact

We may not see wolves on a regular basis, and nobody really wants a poster of a Higgins eye pearly mussel on the wall, but the presence of these creatures is interwoven with the environment we all share. Losing even a small strand in the web of life contributes to the unraveling of our planet's sustainability, the fine balance of biodiversity that affects each and every one of us.