Climate change could result in a planet full of cold-blooded runts.

In a warming world, copepods, tiny crustaceans that make up the bulk of the ocean's animal plankton, could end up stunted. Copepods cope with warmer temperatures by maturing faster, but they don't grow as fast as they mature, so they end up runts.

The same phenomenon, called the “temperature-size rule,” affects most cold-blooded animals, so as the planet heats up, many animals' sizes may go down.

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Researchers at the University of London examined the case of the incredible shrinking organisms in the journal The American Naturalist.

“We’ve shown that growth and development increase at different rates as temperatures warm. The consequences are that at warmer temperatures a species grows faster but matures even faster still, resulting in them achieving a smaller adult size,” said lead author Andrew Hirst in a press release.

Since copepods are food for marine animals, from fish to whales, what happens developmentally to the shrimp-y crustaceans could affect the entire ocean's food web.

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“Decoupling of these rates could have important consequences for individual species and ecosystems,” Hirst added.


A whale shark feasts on plankton. (Wikimedia Commons)