Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Plankton can run, but can’t hide from basking sharks


Basking sharks are much more canny predators than previously thought, ecologists have discovered. According to new research published online by the British Ecological Society’s Journal of Animal Ecology, basking sharks are able to reverse their normal pattern of diving at dawn and surfacing at dusk in order to foil the attempts of zooplankton trying to evade capture. As well as shedding new light on basking behaviour, the results have important implications for the conservation of shark species.

Dr David Sims of the Marine Biological Association and colleagues examined diving behaviour of four basking sharks (Cetorhinus maximus) - two in the shallow sea off Plymouth and two in the deep water off the shelf-edge southwest of Ireland and in northern Clyde Sea in Scotland - using pop-up tags that measure swimming depth, water temperature and light levels. The tags were programmed to detach themselves from the sharks at a set time, float to the surface and then drift with the currents like a “electronic messages in bottles”, before being washed up on beaches and found by the public.

Sims found that while the sharks in deep waters exhibited normal diving behaviour, tracking the zooplankton Calanus up to the surface at dusk and then downward at dawn, sharks in the western English Channel did the reverse. This is the first time this behaviour has been observed among plankton-eating sharks, the authors say, and shows that shark diving behaviour differs predictably between deep waters and in shallow seas close to plankton-rich boundaries in water temperature.

Although the mechanisms underlying this behaviour are unclear, the results indicate that the sharks are responding to changes in vertical migration by the zooplankton. Zooplankton have evolved a range of behaviours to try and avoid being eaten, sometimes staying at greater depths during the day and then feeding near the surface at night but at other times reversing this behaviour in an attempt to throw some of their predators (eg fish larvae and predatory invertebrates such as arrow worms) off their trail. However, this study shows that basking sharks seem to have rumbled them.

As well as shedding new light on behavioural strategies of plankton-feeding sharks and whales, the results have important implications for methods used to monitor populations of basking sharks and other species. “There is concern that the world’s two largest fish species, the whale shark Rhincodon typus and the basking shark, have low population levels as a result of human exploitation. Data on population sizes for these species are lacking, and diving behaviour is one factor contributing to surveying bias,” the authors say. Unless adjusted to account for these differences in diving patterns, current surveys could be over- or underestimating basking shark abundance by at least 10-fold.

Up to 10 metres long and weighing up to 7 tons - about the size of double-decker bus - the basking shark is the world’s second largest fish and feeds by filtering plankton from sea water through its enormous mouth. It is able to filter up to 2,000 tons of water per hour - the equivalent of an Olympic-sized swimming pool. It is harmless to humans, but has been netted and harpooned for its oil which was burned in lamps and more recently for its fins.

Becky Allen | alfa
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Oasis of life in the ice-covered central Arctic

24.10.2016 | Earth Sciences

‘Farming’ bacteria to boost growth in the oceans

24.10.2016 | Life Sciences

Light-driven atomic rotations excite magnetic waves

24.10.2016 | Physics and Astronomy

More VideoLinks >>>