The Bermuda Biological Station for Research (BBSR) is offering visitors and locals the chance to witness one of the most miraculous migrations in the animal kingdom which occurs right here in Bermuda.

As the sun sets over the Sargasso Sea, millions of sea creatures migrate up from the depths to feast on microscopic plants growing in sunlit waters.

At dawn they reverse their course, sinking or swimming down to spend another day in the darkness.

By almost any measure, this daily migration rivals the great seasonal movements of caribou on land or terns in air, yet it is virtually unknown in Bermuda.

The BBSR is now offering a weekly plankton tow excursion on Monday evenings from 7.30 to 9.45 p.m. for anyone who wants to know more about this monumental migration.

The evening trip will be led by one of BBSR's graduate interns and starts with a slide presentation before boarding a boat to tow for plankton in St. George's Harbour. Back in the lab, the plankton is then examined under a microscope.

"We have been getting wonderful feedback from the educational groups who have been staying at BBSR and who have been doing a plankton tow as part of their week's itinerary, and so we decided to open it up to everyone, locals and tourists alike,"' said Nancy Stevens of BBSR.

Scientists came to realise the magnitude of this migration in the 1940's when, during World War II anti-submarine warfare exercises, sailors aboard navy ships detected a puzzling layer on their sonar screens.

This layer or "false bottom" as it was called rose toward the surface each evening and then descended again the next morning.

Submarines were able to hide within this layer using the sonar echo it produced to disguise their own.

Scientists at BBSR are studying these mysteries and, in particular, how the migrating animals' consumption of vast quantities of plant material affects the transfer of carbon dioxide from the atmosphere to the ocean.

Carbon dioxide is the main greenhouse gas released by burning fossil fuels and knowing how long it stays in the atmosphere will help scientists determine how human activities are affecting the Earth's climate.

"After this trip, you will never look at the ocean in the same way again, whether you are eight or 80," said Ms Stevens.

The trips will start on June 11 and will cost $30 for adults and $10 for children and anyone interested should call (297-1880 ext. 0 or visit the BBSR website at www.bbsr.edu.