Seahorses stalk their prey by stealth

Seahorses may appear slow and awkward but they are ferocious and ingenious predators, according to a new study.

The beautiful creatures are famously bad swimmers, but they have a secret weapon to sneak up on their prey.

Their peculiar snouts are shaped to create very few ripples in the water, effectively cloaking them as they creep up and pounce on tiny crustaceans.
 
To their victims, seahorses are more like sea monsters, say scientists from the University of Texas at Austin.
o their victims, seahorses are more like sea monsters, say scientists from the University of Texas at Austin.

"The seahorse is one the slowest swimming fish we know of, but it's able to capture prey that swim at incredible speeds," said Brad Gemmell, author of the study in Nature Communications.
The prey, in this case, are copepods - extremely small crustaceans that are a favoured meal of seahorses, pipefish and sea dragons (Syngnathidae).

When copepods detect waves from predators, they jolt away at speeds of more than 500 body lengths per second - the equivalent of a 6-foot human swimming at 2,000 mph.
Deadly strike

"Seahorses can overcome one of the most talented escape artists in the aquatic world," said Dr Gemmell.

"In calm conditions, they catch their intended prey 90% of the time. That's extremely high, and we wanted to know why."

Seahorses dine by a method known as pivot feeding. Their arched necks act as a spring - allowing them to rapidly rotate their heads and suck their prey in.

But this suction only works at short distances. The effective strike range for seahorses is about 1 millimetre. And a strike happens in less than 1 millisecond.

Until now it was a mystery how such apparently docile creatures managed to get close enough to their prey without being spotted.

To find out, Dr Gemmell and his colleagues studied the dwarf seahorse, Hippocampus zosterae, which is native to the Bahamas and the US.

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