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The number of species that live in the ocean is unknown. While scientists estimate that 91 percent of ocean species have yet to be classified, the global scientific community continues to amass as much knowledge as possible about ocean life. Shown here: Kelp forests within Monterey Bay National Marine Sanctuary.
- How Much of The Ocean Have We Explored
Scientists estimate there may be between 700,000 and 1...
- How Much of The Ocean Have We Explored
- Leatherback turtle. Leatherback turtles are the largest species of marine turtle, usually growing to around 2 metres long. Leatherbacks get their name from their black, leathery shell and are unique among reptiles in that they can metabolically raise their body temperature above that of their surrounding environment, allowing them to survive in colder waters.
- Basking shark. Basking sharks can reach lengths of up to 12 metres and are second in size only to the gigantic whale shark. Their huge mouths can be up to a metre wide but these gentle giants are filter feeders, meaning they mostly dine on plankton.
- Seahorses. There are two species around the British coastline, the Spiny Seahorse (Hippocampus guttulatus) and the Short Snouted Seahorse (Hippocampus hippocampus)
- Curled octopus. These guys grow up to 50cm and are found all around the UK and Irish coast. They get their name from the fact that when they’re sitting at rest they curl up the end of their tentacles.
- Overview
- Narrow safety margins
- Photos of the Pacific Ocean
- Wider impact
- Beyond the sea
Climate change is being more keenly felt by the sea's cold-blooded creatures.
As the world's average temperatures creep higher, marine animals are far more vulnerable to extinctions than their earthbound counterparts, according to a new analysis of more than 400 cold-blooded species.
With fewer ways to seek refuge from warming, ocean-dwelling species are disappearing from their habitats at twice the rate of those on land, notes the research published Wednesday in the journal Nature.
The study, led by researchers from New Jersey's Rutgers University, is the first to compare the impacts of higher temperatures in the ocean and on land for a range of cold-blooded wildlife, from fish and mollusks to lizards and dragonflies.
While previous research has suggested warm-blooded animals are better at adapting to climate change than cold-blooded ones, this study punctuates the special risk for sea creatures. As the oceans continue to absorb heat trapped in the atmosphere from carbon dioxide pollution, bringing waters to their warmest point in decades, undersea denizens don't have the luxury of ducking into a shady spot or a burrow.
"Marine animals live in an environment that, historically, hasn't changed temperature all that much," says Malin Pinsky, an ecologist and evolutionary biologist at Rutgers who led the research. "It's a bit like ocean animals are driving a narrow mountain road with temperature cliffs on either side."
The scientists calculated "thermal safety margins" for 88 marine and 318 terrestrial species, determining how much warming they can tolerate and how much exposure they have to those heat thresholds. The safety margins were slimmest near the equator for ocean dwellers and near the midlatitudes on land.
For many, the heat is already too much. At the warm edges of the marine species' ranges, the study found, more than half had disappeared from historical territory as a result of warming. The rate for these local extinctions is twice that seen on land.
"These impacts are already happening. It's not some abstract future problem," Pinsky says.
The narrow safety margins for tropical marine animals, such as colorful damselfish and cardinalfish, average about 10 degrees Celsius. "That sounds like a lot," Pinsky says, "but the key is that populations actually go extinct long before they experience 10 degrees of warming."
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A California sea lion hunts for fish on a kelp paddy at Cortes Bank, a seamount off San Diego.
A California sea lion hunts for fish on a kelp paddy at Cortes Bank, a seamount off San Diego.
Photograph by Brian Skerry, Nat Geo Image Collection
Even just a degree or half-degree boost, he adds, can lead to trouble finding food, reproducing, and other devastating effects. While some species will be able to migrate to new territory, others—coral and sea anemones, for example—can't move and will simply go extinct.
"This is a really heavy hitting paper because it contributes hard data to support the long-standing assumption that marine systems have some of the highest vulnerabilities to climatic warming," says Sarah Diamond, an ecologist and assistant professor at Case Western Reserve University in Cleveland, Ohio who did not work on the paper. "This is important because marine systems can get overlooked."
Most humans are landlubbers, after all—though many of our foods and jobs are tied to seaborne economies. Pinsky points to species such as Atlantic halibut, winter flounder, and ocean quahog that have disappeared from historical habitats and are important to fisheries.
In addition to cutting the greenhouse gas emissions that are causing climate change, he says that stopping overfishing, rebuilding overfished populations, and limiting ocean habitat destruction could help address species loss.
"Setting up networks of marine protected areas that act as stepping stones as species move to higher latitudes," he adds, "could help them cope with climate change going forward."
The Rutgers study reflects how important it is to measure not just temperature changes but how they affect animals, says Alex Gunderson, an assistant professor of ecology and evolutionary biology at Tulane University in New Orleans who did not work on the study.
And that includes those who live on the land.
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Related: See the artificial nests helping these birds survive climate change
"Land animals are at lower risk than marine animals only if they can find cool shaded spots to avoid direct sunlight and wait out extreme heat," Gunderson points out.
"The results of this study are a further wake-up call that we need to protect forests and other natural environments because of the temperature buffer that they provide wildlife in a warming world."
- Christina Nunez
- 1 min
Based on the World Register of Marine Species (WoRMS), there are currently (2022 census) about 242,000 known and described marine species living in the world's oceans. Marine biota continue to be discovered and named at a current average of 2,332 new species per year. The time span between the collection of the first specimen of a new species ...
Oceans make up roughly 99.5% of the planet's habitats by volume, and within those largely unexplored depths there are thought to be scores of large marine animals unknown to science. When you ...
During the decade of the Census of Marine Life, more than 6,000 potential new ocean species were discovered by the roughly 2,700 participating scientists from more than 80 countries. Census scientists searched the global ocean to learn more about species as large as the blue whale and as small as a zooplankter or microbe.
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Nov 30, 2017 · The very high estimates (any larger than 10m) are now thought unlikely by many, but current common estimates still vary between around 0.3m and 2m marine species. New way of recording species
