The Upshot

Cannibal shrimp: The invasion has begun

The Upshot

Do not be alarmed, but the cannibal shrimp invasion has begun.

The influx of the jumbo-sized shrimp (which look more like a small lobster than the little pink crustaceans you see at the grocery store) has increased 10 times in the last year, according to a report from the U.S. Geological Survey—from 32 in 2010 to 331 in 2011. The shrimp-eating shrimp have been spotted in waters from North Carolina to Texas.

Tony Reisinger of the Texas Sea Grant Extension Service, told CNN that the tiger prawn "are cannibalistic as are other shrimp, but it's larger so it can consume the others."

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The black-and-white-striped sea creatures have shown up in the Gulf of Mexico and Southeast coast and, unlike their bottom-feeding cousins, are big enough—up to 13 inches long and up to a quarter-pound—to gobble up smaller shrimp.

Researchers worry that the Asian cannibal species is preying on the smaller, native sea life, competing for resources and carrying disease.

The increase "is the first indication that we may be undergoing a true invasion of Asian tiger shrimp," said marine ecologist James A. Morris, who works for the National Oceanic and Atmospheric Administration's Center for Coastal Fisheries and Habitat Research.

Scientists don't know exactly how the Asian variety got to the Gulf Coast—the possibilities include breeding in the local waters or being carried to the area by currents.

No matter how they got to the U.S., they're not welcome. Said Morris, "The Asian tiger shrimp represents yet another potential marine invader capable of altering fragile marine ecosystems."

The  numbers are probably much higher than the reported amount. Pam Fuller, the USGS biologist who runs the agency's Nonindigenous Aquatic Species database, said, "The more fisherman and other locals become accustomed to seeing them, the less likely they are to report them."

The USGS will next look into the tiger shrimp DNA for clues to its origins, and asks anyone who spots a tiger shrimp to report its location to the USGS.

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