. Earth Science News .

A whole new meaning for thinking on your feet
by Staff Writers
Panama City, Panama (SPX) Dec 16, 2011

Nephila clavipes, a big tropical spider, has plenty of room in its body for its brain. Credit: Pamela Belding, STRI.

Smithsonian researchers report that the brains of tiny spiders are so large that they fill their body cavities and overflow into their legs. As part of ongoing research to understand how miniaturization affects brain size and behavior, researchers measured the central nervous systems of nine species of spiders, from rainforest giants to spiders smaller than the head of a pin.

As the spiders get smaller, their brains get proportionally bigger, filling up more and more of their body cavities.

"The smaller the animal, the more it has to invest in its brain, which means even very tiny spiders are able to weave a web and perform other fairly complex behaviors," said William Wcislo, staff scientist at the Smithsonian Tropical Research Institute in Panama.

"We discovered that the central nervous systems of the smallest spiders fill up almost 80 percent of their total body cavity, including about 25 percent of their legs."

Some of the tiniest, immature spiderlings even have deformed, bulging bodies. The bulge contains excess brain. Adults of the same species do not bulge.

Brain cells can only be so small because most cells have a nucleus that contains all of the spider's genes, and that takes up space.

The diameter of the nerve fibers or axons also cannot be made smaller because if they are too thin, the flow of ions that carry nerve signals is disrupted, and the signals are not transferred properly. One option is to devote more space to the nervous system.

"We suspected that the spiderlings might be mostly brain because there is a general rule for all animals, called Haller's rule, that says that as body size goes down, the proportion of the body taken up by the brain increases," said Wcislo. "Human brains only represent about 2-3 percent of our body mass.

Some of the tiniest ant brains that we've measured represent about 15 percent of their biomass, and some of these spiders are much smaller."

Brain cells use a lot of energy, so these small spiders also probably convert much of the food they consume into brain power.

The enormous biodiversity of spiders in Panama and Costa Rica made it possible for researchers to measure brain extension in spiders with a huge range of body sizes.

Nephila clavipes, a rainforest giant weighs 400,000 times more than the smallest spiders in the study, nymphs of spiders in the genus Mysmena.

Quesada, Rosanette, Triana, Emilia, Vargas, Gloria, Douglass, John K., Seid, Marc A., Niven, Jeremy E., Eberhard, William G., Wcislo, William T. 2011. "The allometry of CNS size and consequences of miniaturization in orb-weaving and cleptoparasitic spiders." Arthropod Structure and Development 521-529, doi10.1016/j.asd.2011.07.002

Related Links
Smithsonian Tropical Research Institute
Darwin Today At TerraDaily.com

Get Our Free Newsletters Via Email
Buy Advertising Editorial Enquiries


. 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

Swarms of bees could unlock secrets to human brains
Sheffield UK (SPX) Dec 15, 2011
Scientists at the University of Sheffield believe decision making mechanisms in the human brain could mirror how swarms of bees choose new nest sites. Striking similarities have been found in decision making systems between humans and insects in the past but now researchers believe that bees could teach us about how our brains work. Experts say the insects even appear to have solved indeci ... read more

Mob involved in Fukushima clean-up: Japan reporter

Japan set to declare Fukushima plant shutdown

The hermit of Fukushima 'staying put' despite risks

Scientists Assess Radioactivity in the Ocean from Japan Nuclear Power Facility

Researchers explain granular material properties

Stress causes clogs in coffee and coal

New eco-friendly foliar spray provides natural anti-freeze

Amazon selling over one million Kindles a week

Sewage treatment plants may contribute to antibiotic resistance problem

Species, and threats grow in Mekong region: WWF

Brazil's Belo Monte dam better than alternatives: study

Mekong nations meet on controversial Laos dam

South Pole conquest hailed 100 years on with eye on climate

Antarctic expedition checks CryoSat down-under

GPS Reveals 2010 Spike In Greenland Ice Loss Lifted Bedrock

Plunge in CO2 put the freeze on Antarctica

Salt-tolerant crops show higher capacity for carbon fixation

Earliest Known Bug-Repellant Plant Bedding Found at South African Rock Shelter

As climate change sets in, plants and bees keep pace

Nature's medicine cabinet could yield hundreds of new drugs

Thai flood death toll exceeds 700

Major 7.1 quake strikes Papua New Guinea: USGS

Mexico unrattled one day after quake

Major 6.5 quake hits southern Mexico, 2 dead

Casamance rebel faction condemns attack on Senegal troops

Poverty blights S.Africa's liberation army veterans

Newest nation South Sudan ravaged by war, climate

US troops deploy in LRA rebel hunt: Uganda army

The Disappearance of the Elephant Caused the Rise of Modern Man

Survival of the fittest: Linguistic evolution in practice

Taxi driver training changes brain structure

Why Are Humans Not Smarter


The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. 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