Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. Earth Science News .




WATER WORLD
Deep-Sea Crabs Seek Food Using Ultraviolet Vision
by Staff Writers
Hollywood FL (SPX) Sep 10, 2012


File image: Deep-sea crab.

Some deep-sea crabs have eyes sensitive to ultraviolet light, which they may use to snatch glowing plankton and stuff it in their mouths, a new Nova Southeastern University study suggests.

Tamara Frank, Ph.D., a marine biologist and associate professor at Nova Southeastern University's Oceanographic Center, who is the principal investigator of the study, said that crabs living the deep-sea zone - a pitch dark area at the ocean bottom - may be using bioluminescence to help sort out their food.

Duke University marine biologist Sonke Johnsen. Ph.D., one of the study's collaborators, explained that the animals might be using their ultraviolet and blue-light sensitivity to sort out the likely toxic corals they're sitting on - which glow, producing blue-green and green bioluminescence - from the plankton they eat, which glow blue.

The sensitivity to shorter ultraviolet wavelengths may give the crabs a form of color vision to guarantee they grab healthy grub, not poison. Frank and her collaborators reported the findings in the Sept. 6 issue of the Journal of Experimental Biology.

Frank has previously shown that certain deep-sea shrimp living in the water column can see ultraviolet wavelengths, even though they live nearly half a mile below the ocean surface, where there's little to no sunlight. Experiments to test deep-sea creatures' sensitivity to light have rarely been done on animals that live on the bottom of the ocean. The new study is one of the first to test how bottom-dwelling animals respond to light.

The team of scientists studied three ocean-bottom sites near The Bahamas. They took video and images of the regions, recording how crustaceans ate and the wavelengths of light, or color, at which neighboring animals glowed by bioluminescence. The scientists also captured and examined the eyes of eight crustaceans found at the sites and several other sites on earlier research cruises.

To capture the crustaceans, the team used the Johnson-Sea-Link submersible. During the dive, crustaceans were gently suctioned into light-tight, temperature-insulated containers. They were brought to the surface, where Frank placed them in holders in her shipboard lab and attached a microelectrode to each of their eyes.

She then flashed different colors and intensities of light at the crustaceans and recorded their eye response with the electrode. From the tests, she discovered that all of the species were extremely sensitive to blue light and two of them were extremely sensitive to both blue and ultraviolet light.

The two species sensitive to blue and UV light also used two separate light-sensing channels to make the distinction between the different colors. It's the separate channels that would allow the animals to have a form of color vision, said Johnsen, who is an expert in optics.

During a sub dive, Johnsen used a small, digital camera to capture one of the first true-color images of the bioluminescence of the coral and plankton at the sites. In this "remarkable" image, the coral glows greenish, and the plankton, which is blurred because it's drifting by as it hits the coral, glows blue, he said.

Video of the crabs placidly sitting on a sea pen, periodically picking something off corals and putting it in their mouths, and the data showing the crabs' sensitivity to blue and UV light, suggests that they have the ability color code their food. The idea is "still very much in the hypothesis stage, but it's a good idea," Johnsen said.

To further test the hypothesis, the scientists need to collect more crabs and test the animals' sensitivity to even shorter wavelengths of light. That might be possible, but the team will have to use a different sub, since the Johnson-Sea-Link is no longer available.

Another challenge is to find out whether the way the crabs are acting in the video is natural.

"Our subs, nets and ROVs greatly disturb the animals," Johnsen said. "So we're stuck with what I call forensic biology. We collect information about the animals and the environment, and then try to piece together the most likely story of what happened."

The story looks like crabs that are color-coding their food, he said.

.


Related Links
Nova Southeastern University
Water News - Science, Technology and Politics






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





WATER WORLD
New study examines how ocean energy impacts life in the deep sea
Durham NC (SPX) Sep 10, 2012
A new study of deep-sea species across the globe aims to understand how natural gradients in food and temperature in the dark, frigid waters of the deep sea affect the snails, clams, and other creatures that live there. Similar studies have been conducted for animals in the shallow oceans, but our understanding of the impact of food and temperature on life in the deep sea - the Earth's largest a ... read more


WATER WORLD
Japan slams brakes on $63 billion in spending

25 killed in ammunition depot blast in western Turkey: army

Two slightly injured in accident at French nuclear plant

Congo, China, sign 975m-euro deal to rebuild Brazzaville

WATER WORLD
World watches for 'iPhone 5' unveiling Wednesday

Airborne observatory and electronic noses - DLR presents new space developments at ILA

Estonian first graders to learn computer code

Tough gel stretches to 21 times its length, recoils, and heals itself

WATER WORLD
Deep-Sea Crabs Seek Food Using Ultraviolet Vision

Bright life on the ocean bed: Predators may even color code food

Chikyu Sets a New World Drilling-Depth Record of Scientific Ocean Drilling

Study identifies prime source of ocean methane

WATER WORLD
Glacial thinning has sharply accelerated at major South American icefields

Russia charges Greenpeace activists in polar bear protest

Russia's unique economic position in the Arctic

Major world interests at stake in Canada's vast Mackenzie River Basin

WATER WORLD
Wild bees: Champions for food security and protecting our biodiversity

US fruit giant Dole settles 38 pesticide complaints

Spinach power gets a big boost

Bees, fruits and money

WATER WORLD
Nicaragua eruption forces 3,000 to evacuate

Hurricane Michael weakens in Atlantic: forecasters

Floods kill 18 in Burkina Faso, leave 21,000 homeless

China quakes kill at least 80

WATER WORLD
Nigeria trains more peacekeeping troops

Kenya readies Somali Kismayo attack

Rebel chief returns to Chad after surrender

Weapons destined for Mali held up in Guinea since July

WATER WORLD
Researchers identify biochemical functions for most of the human genome

Major advances in understanding the regulation and organization of the human genome

Yale team finds order amidst the chaos within the human genome

Benign malaria key driver of human evolution in Asia-Pacific




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement