Fish Follow Their Noses Back Home

[mrmoshe]

Fish follow their noses back home

BABY tropical fish, drifting at the mercy of ocean currents, probably follow their noses back to their home reefs when they grow large enough to swim, US researchers say.

Fish that dwell on Australia's Great Barrier Reef generally like to stick close to home, where they know where to find food and hide from predators.

But in their first few weeks of life, lacking the ability to swim, larval fish can drift up to 30km from where they were born.

They probably relied on their sense of smell to make their way back home, according to scientists at the Marine Biological Laboratory in Woods Hole, Massachusetts.

Much as subway users looked for signs to make sure they were on the right train, the fish used smell to find an ocean current, several of the facility's biologists found.

"Fish have as good a nose as anybody," said Jelle Atema, a professor at Boston University and Woods Hole who took part in the research.

"You think of dogs and rats as super smellers but eels and catfish and hammerhead sharks are at least as good."

The cardinal fish, popular in home aquariums, prefers to stay on the reef on which it was born and uses its nose to distinguish one reef from another, he said.

The neon damselfish, another popular aquarium species found throughout the Pacific, was not as picky and can live on several reefs. This fish used its sense of smell to find its way back to safety when it drifted toward the open ocean, Professor Atema said.

The biologists were not able to prove conclusively that fish navigate by smell, but Prof Atema said their sense of hearing would not help them in distances over 1km.

The findings will be published this week in the Proceedings of the National Academy of Sciences.