Jellyfish 'can sense ocean currents'

23 January 2015 Last updated at 08:39

By Victoria GillScience reporter, BBC News

The swimming jellyfish were tagged with data loggers fitted to their bodies with cable ties

Jellyfish can sense the ocean current and actively swim against it, according to a study that involved tagging and tracking the creatures.

The research, by an international team, could help scientists work out how jellyfish form "blooms".

These blooms may comprise between hundreds and millions of jellyfish, and can persist in a given area for months.

It remains unclear just how the jellyfish sense changes in water, the paper in Current Biology journal says.

The scientists, including researchers from Swansea University and Deakin University in Warnambool, Australia, tagged 18 large barrel jellyfish (Rhizostoma octopus) in the Bay of Biscay, off the coast of France.

The team caught the jellyfish and fitted them with loggers that measured acceleration and body orientation.

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Sea Monkey Study Suggests Zooplankton Migrations May Affect Ocean Currents

October 1, 2014

April Flowers for redOrbit.com – Your Universe Online

In 1957, the world was introduced to Sea Monkeys, and people were fascinated. Sea Monkeys were advertised in nearly every popular comic book, and even made a trip to space with Astronaut John Glenn in 1998 aboard Space Shuttle Discovery. The public’s fascination with the tiny brine shrimp known as Sea Monkeys mostly stems from the fact that the dehydrated eggs hatch, develop and mate given little more than a tank of salt water.

Physicists study brine shrimp for even shorter-term patterns than the life cycle. They are interested in the vertical migration that brine shrimp, and other zooplankton, engage in. Large groups migrate from the surface at night to deeper environments during the day in response to changing light conditions.

According to a new study from the California Institute of Technology (Caltech), this pattern of migration creates water currents much larger than the sum of those created by individual organisms. The study, published in Physics of Fluid, suggests that global ocean circulation patterns can be affected by the collective movement of small marine organisms on a level comparable to the wind and tides.

Brine shrimp (Artemia salina) display a tendency to move toward a light source, a phenomenon called phototaxis. Caltech researchers Monica Wilhelmus and John Dabiri induced a vertical migration pattern in a swarm of the tiny crustaceans in a large water tank using lasers of different colors. When the researchers used a blue laser in a rising motion along the side of the tank, the brine shrimp moved upward. When a green laser was kept above the tank, the shrimp stayed centered. Microscopic silver-coated glass spheres were released into the water, allowing the team to visualize the resulting currents by capturing their changing distribution throughout the migration with a high speed camera.

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