Killer Shrimp Invades British Isles

Researchers in the United Kingdom are currently trying to figure out how is it that their national waters are starting to swarm with killer shrimps. These are voracious predators, which have the nasty habit of killing lesser creatures just for the fun of it, without actually eating them.

The marine creature is merciless, killing its intended victims by ripping them apart. Lesser animals easily fall prey to its insatiable appetite, so much so that researchers are fearing an extermination of certain indigenous species.

This would have devastating consequences on a number of ecosystems, because it would primarily throw existing food webs off-balance. The effects would also be cumulative to those caused by other stress factors, such as global warming and oceanic acidification.

The killer shrimp, called Dikerogammarus villosus, most likely originated in western Asia, the investigators say. In all fairness, this crustacean is an amphipod, not actually a real shrimp.

It can kill and maim indiscriminately due to its extremely large and strong mouthparts, which are way too big for a 1.2-inch (3-centimeter) creature. Due to its viciousness, it has received the nickname of killer shrimp, LiveScience reports.

In the animal kingdom, it's highly unusual for predators to kill other creatures without devouring them. Instances in which this happens are very rare, and this amphipod is apparently a part of this very exclusive group.

“As prey numbers increase, Dikerogammarus appear to increase their attack rate far more strongly than other similar amphipod crustaceans,” explains Cardiff University freshwater ecologist Steve Ormerod.

“At present, we have no explanation for this behavior,” the researcher says. He adds that the creature reached central and western Europe via large rivers such as the Danube and the Rhine.

Its origins can be traced back to the Black and Caspian seas, scientists say. “Dikerogammarus appears to be an extremely voracious predator and competitor, killing and eating its prey at a far faster rate than other similar animals,” Ormerod adds.

“It also breeds very rapidly, and has quickly established large populations that appear so far to be unchecked by natural enemies,” he explains further.

“There are now major concerns that it might start to colonize other locations because it has reached such large densities at least at one of the occupied locations – in the 200-hectare lake at Cardiff Bay, intensively used by people for recreation,” the investigator says.

“Numbers reach up to 4,000 individuals per square meter,” Ormerod concludes.