Species extinction: how long animals will last before disappearing

The majestic blue whale roamed the seas for about 4.5 million years, while the Neanderthals disappeared from existence in a few hundred thousand years.

But are these creatures representative of species in general? And how long do species usually last before extinction?

It turns out that the answer we find now may be very different from what it usually is. Due to habitat destruction, climate change, and a host of other factors, plants and animals are disappearing from the planet faster than all but five other points in history.

Some experts say we're in the sixth mass extinction event. But even in the quieter periods of Earth's history, the answer has varied depending on the species. For mammals, the average species exists from one to two million years, according to an article in People & the Planet.

However, this average does not hold up during all geological periods and for all mammals. The average epoch of modern life (65 million years ago until now) is 3.21 million years, with larger mammals lasting longer than smaller ones, according to a 2013 study in the Journal of Integrative Animal Science.

And for invertebrate species, the duration is even more impressive; They last between 5 million to 10 million years on average.

Experts do not agree on the average time for these species in any class to become extinct. The fossil record documents when a species appears and when it disappears, but it leaves a large margin of error because the conditions must be ideal for the formation of fossils, and these conditions are not always present when a species appears. And these longevity stats aren't helpful anyway.

Stuart Beam, a leading extinction expert and conservation ecologist at Duke University's Nicholas School of the Environment, said he prefers to think about extinction in terms of how many species die each day, month or year.

"It's easier to think about mortality rates, largely because there are some species that live for a really long time. Then there are other species that don't last long," Bim said.

The species mortality rate, called the extinction rate, is also controversial. Bem put the historical figure - a figure that covers all times, except for mass extinctions - of roughly one species per million species annually. This means that if there are a million species on this planet, then one of them will become extinct every year.

However, other experts estimate that species typically die at a rate of 0.1 species per million annually.

The current extinction rate is said to be much higher than any of these predictions about the past - about 1,000 times more than Bem's estimate of the extinction rate. However, not everyone agrees how species extinction is now accelerating, said Tierra Carey, chief scientist at the Oregon Biodiversity Center.

Some experts estimate that the current extinction rate is only 100 times faster or, on the other hand, 10,000 times faster.

There are several reasons why estimates of the current rate of extinction differ. "The rate of extinction depends on how many species there are on Earth and how quickly they will go extinct," Carey said. "Nobody knows the answer to any of these questions."

Bim added that about 90% of the living species - mostly insects - may not have been named. And if researchers do not know that a species exists, they will not know that it has become extinct. Another complication is that it can be difficult to know when the species has died. And just because researchers haven't seen it for several years doesn't mean it's gone forever. And the calculations can get more difficult when species become extinct in the wild.

And there's one thing experts agree on: the recent extinction rate is very high. "The species adapt as quickly as possible," Bim said. "But eventually, luck runs out, they don't adapt quickly enough, and they go extinct."

Source: Live Science