Featured Research

from universities, journals, and other organizations

Fish schools and krill swarms take on common shape

Date:
September 18, 2010
Source:
Cell Press
Summary:
When fish or tiny, shrimp-like krill get together, it appears they follow the same set of "rules." According to a new study, shoals of fish and swarms of krill hang out in groups that take on the same overall shape; it's not a simple sphere, a cylinder, or ovoid, but something more akin to an irregular crystal, the researchers say.

Shoals of fish and swarms of krill hang out in groups that take on the same overall shape, which can be explained by a model in which individual fish and krill juggle only their access to oxygen-rich water and their risk of being eaten by predators.
Credit: iStockphoto/Island Effects

When fish or tiny, shrimp-like krill get together, it appears they follow the same set of "rules." According to a new study published online on Sept. 16 in Current Biology, a Cell Press publication, shoals of fish and swarms of krill hang out in groups that take on the same overall shape; it's not a simple sphere, a cylinder, or ovoid, but something more akin to an irregular crystal, the researchers say.

"The fact that several species of fish and krill that live in very different locations -- from the tropics to polar oceans -- form shoals that are the same shape suggests that the same forces are at play in diverse ecosystems; there is a common 'rule' for shoal shape," said Andrew Brierley of the University of St Andrews in Scotland.

Of course, many types of animals live or travel in groups: deer herd, bees swarm, and birds flock, Brierley said. Marine animals do this too, but the details of their behavior have been much less known, given the difficulty of observing them in their undersea surroundings.

In the new study, Brierley and his colleague Martin Cox relied on multibeam sonar to record the three-dimensional structure of Antarctic krill swarms. Those studies showed that the krill maintained a fixed surface area:volume ratio (approximately 3.3 m?1), even as the overall size and density of the group varied greatly. Studies of fish, including sardines and anchovies, from diverse locations turned up the very same pattern.

That came as quite a surprise, Brierley said, because "there are not many 'rules' in biology, and straight-line relationships are not at all common."

In an attempt to work out why this shape emerges, the researchers turned to computer modeling. And the answer appears to be rather simple: That shoal shape can be explained by a model in which individual fish and krill juggle only their access to oxygen-rich water and their risk of being eaten by predators.

Brierley said that he expects this pattern will prove very general, although there will surely be exceptions. But changes are in store.

Oxygen availability is a major driver of shoal shape, and oxygen concentrations in the world ocean are declining as the ocean warms, Brierley explained. That means that shoals will have to adapt accordingly. Specifically, as oxygen dwindles, shoals would be expected to shrink in size or become less densely packed. And that may have practical consequences.

"The ease (or difficulty) with which fishermen can catch pelagic fish and crustaceans -- catchability -- can vary as a function of shoal size, so understanding the response of shoals to changing oxygen concentration will be of commercial as well as ecological importance," the researchers wrote.

The researchers include Andrew S. Brierley, and Martin J. Cox, of Pelagic Ecology Research Group, Gatty Marine Laboratory, University of St Andrews, Fife, Scotland, UK.


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Journal Reference:

  1. Andrew S. Brierley, and Martin J. Cox. Shapes of Krill Swarms and Fish Schools Emerge as Aggregation Members Avoid Predators and Access Oxygen. Current Biology, 2010; DOI: 10.1016/j.cub.2010.08.041

Cite This Page:

Cell Press. "Fish schools and krill swarms take on common shape." ScienceDaily. ScienceDaily, 18 September 2010. <www.sciencedaily.com/releases/2010/09/100916121320.htm>.
Cell Press. (2010, September 18). Fish schools and krill swarms take on common shape. ScienceDaily. Retrieved April 23, 2014 from www.sciencedaily.com/releases/2010/09/100916121320.htm
Cell Press. "Fish schools and krill swarms take on common shape." ScienceDaily. www.sciencedaily.com/releases/2010/09/100916121320.htm (accessed April 23, 2014).

Share This



More Plants & Animals News

Wednesday, April 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Leopard Bites Man in India

Raw: Leopard Bites Man in India

AP (Apr. 22, 2014) A leopard caused panic in the city of Chandrapur on Monday when it sprung from the roof of a house and charged at rescue workers. (April 22) Video provided by AP
Powered by NewsLook.com
Iowa College Finds Beauty in Bulldogs

Iowa College Finds Beauty in Bulldogs

AP (Apr. 22, 2014) Drake University hosts 35th annual Beautiful Bulldog Contest. (April 21) Video provided by AP
Powered by NewsLook.com
805-Pound Shark Caught Off The Coast Of Florida

805-Pound Shark Caught Off The Coast Of Florida

Newsy (Apr. 22, 2014) One Florida fisherman caught a 805-pound shark off the coast of Florida earlier this month. Video provided by Newsy
Powered by NewsLook.com
Breakfast Foods Are Getting Pricier

Breakfast Foods Are Getting Pricier

AP (Apr. 21, 2014) Breakfast is now being served with a side of sticker shock. The cost of morning staples like bacon, coffee and orange juice is on the rise because of global supply problems. (April 21) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins