Chaiwat Subprasom/Reuters
People look at a 16-year-old critically endangered Hawksbill turtle after releasing it into the sea at the Sea Turtle Conservation Center of the Royal Thai Navy, in Sattahip, Chonburi province, east of Bangkok August 10, 2010.
- The planet is experiencing a mass extinction- the sixth time in Earth's history that a wide swath of species are seeing a major collapse in their populations.
- Human activities are to blame: pollution, farming, and deforestation are destroying natural habitats, while carbon emissions are causing the oceans to warm at unprecedented rates.
- According to a recent report from the United Nations, up to 1 million plant and animal species are threatened with extinction, many within decades.
- Marine species have experienced fewer extinctions than their land-based counterparts, but 15 ocean animals have gone extinct in the last 100 years, and 72 more are on the verge of extinction.
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A growing body of evidence suggests the planet is in the midst of a sixth mass extinction. Animal species around the world are being hit on multiple fronts as habitat loss, hotter oceans, and climate change drive their populations down at unprecedented rates.
According to a recent United Nations report, up to 1 million plant and animal species are threatened with extinction, and many could disappear within decades.
The report blamed one factor for this trend: humans. Pollution, deforestation, and habitat destruction due to farming and development have already "severely altered" 75% of all land and 40% of marine environments, it said.
Read More: 17 signs we're in the middle of a 6th mass extinction
A 2017 study suggested the Earth is undergoing a process of "biological annihilation." As many as half of the total number of animal individuals that once shared the planet with us are already gone, it found.
Although the oceans absorb 93% of the excess heat trapped on Earth due to greenhouse gases, far fewer ocean species have gone extinct over the past 500 than those on land so far. A 2015 study noted that, according to the International Union for the Conservation of Nature (IUCN), just 15 marine animals had gone extinct by then, compared to 514 terrestrial animal species.
That ratio could shift in the coming years, though. Here are the 15 extinct ocean animals (that we know of), along with a dozen others that are on the verge of extinction.