New discovery -- copepods share 'diver's weight belt' technique with whales

June 13, 2011

A deep-sea mystery has been solved with the discovery that the tiny 3 mm long marine animals, eaten by herring, cod and mackerel, use the same buoyancy control as whales.

Reporting this week in the journal Limnology and Oceanography, researchers from British Antarctic Survey describe how copepods – a crustacean rich in omega-3 oil – 'hibernates' in the deep ocean during winter when seas are stormy and food scarce. To reach the ocean depths the copepod's oily body fluids undergo a remarkable transformation. As the animals swim deeper, water pressure triggers a process that converts their oil to a more solid form rather like the consistency of butter. This change in density acts like a 'diver's weight belt', enabling them to be neutrally buoyant and spend winter in deep waters without wasting energy on constant swimming.

Lead author from British Antarctic Survey, Dr David Pond says, "This work is of particular value from a number of angles. Copepods may be exceptionally small creatures but they represent a vast reserve of ocean 'biomass' that provides a crucial component of the food chain.

"We've known for some time that there is a link between the copepod's large stores of energy-rich oil and 'hibernation' behaviour, but this is the first time that we've been able to understand the exact relationship between these two elements in the animal's life cycle. This discovery is a breakthrough and will help enormously with the development of simulations of their behaviour.

It's fascinating also to think that the largest and the smallest share this remarkable ability to change their body fats to adjust their buoyancy."

Explore further: Antarctic krill provide carbon sink in Southern Ocean

More information: The paper, Phase transitions of wax esters adjust buoyancy in diapausing Calanoides acutus by David W Pond and Geraint A Tarling is published in Limnology and Oceanography. 56: 1310-1318.

Related Stories

Antarctic krill provide carbon sink in Southern Ocean

February 6, 2006

New research on Antarctic krill (Euphausia superba), a shrimp-like animal at the heart of the Southern Ocean food chain, reveals behaviour that shows that they absorb and transfer more carbon from the Earth’s surface than ...

First comprehensive 'inventory' of life in Antarctica

December 1, 2008

The first comprehensive "inventory" of sea and land animals around a group of Antarctic islands reveals a region that is rich in biodiversity and has more species than the Galapagos. The study provides an important benchmark ...

Study reveals most biologically rich island in Southern Ocean

May 25, 2011

The first comprehensive study of sea creatures around the sub-Antarctic island of South Georgia reveals a region that is richer in biodiversity than even many tropical sites, such as the Galapagos Islands. The study provides ...

Recommended for you

New gene map reveals cancer's Achilles heel

November 25, 2015

Scientists have mapped out the genes that keep our cells alive, creating a long-awaited foothold for understanding how our genome works and which genes are crucial in disease like cancer.

Insect DNA extracted, sequenced from black widow spider web

November 25, 2015

Scientists extracted DNA from spider webs to identify the web's spider architect and the prey that crossed it, according to this proof-of-concept study published November 25, 2015 in the open-access journal PLOS ONE by Charles ...

Study suggests fish can experience 'emotional fever'

November 25, 2015

(—A small team of researchers from the U.K. and Spain has found via lab study that at least one type of fish is capable of experiencing 'emotional fever,' which suggests it may qualify as a sentient being. In their ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.