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Tuesday, October 13, 2009

Plant-eating spider found in Central America

"Scientists have found a spider in Central America that eats mostly plants, the only known vegetarian in an estimated 40,000 spider species.
Bagheera kiplingi is a jumping spider that lives in Central America and southern Mexico. It feeds mostly on the nutrient-rich nectar and specialized leaf structures of acacia trees.
Acacia trees and certain ants have co-evolved into a mutually beneficial relationship. The trees gives the ants food — nectar and specialized leaf tips called Beltian bodies — and shelter in the plant's hollow spines, while the ants defend the plant against other animals.
B. kiplingi exploit this relationship by eating the acacia nectar and Beltian bodies without helping to defend the plant.
The vegetarian spider uses the sharp eyes and agility it shares with other jumping spiders not to hunt the ants that patrol the acacia bush, but to avoid them.
Eric Olson of Brandeis University first discovered B. kiplingi in 2001, and co-authored the full description appearing this week in the journal Current Biology.
"What surprised us most about discovering this spider's extraordinary ecology was to find it on the ant-acacias," said co-author Robert Curry of Villanova University, in a statement. "This well-known mutualism has been studied by tropical ecologists for nearly 50 years, yet the spider's role was not noticed until Olson's discovery in 2001."
Curry's student, Christopher Meehan, independently observed the same herbivorous behaviour in spiders in Quintana Roo, south of Cancun, Mexico.
The researchers took high-resolution video of the spiders to monitor what they were eating. In the Mexican population, the Beltian bodies of acacia trees made up 90 per cent of the 140 food items the spider ate.
The spiders also supplement their vegetarian diet with some animal products, such as ant larvae. Meat eating was more frequent in the Costa Rican spiders than in the Mexican ones.
The scientists backed up their direct observations of the spiders' eating habits with laboratory analysis of the plants, ants, Bagheera spiders and other local spiders. The molecular analysis, conducted with the help of scientists at Queen's University in Kingston, Ont., found that the diet of Bagheera spiders was more similar to the ants than to other spiders.
The researchers also found another characteristic that makes B. kiplingi unique among spiders: the males help care for eggs and young."

Source:http://www.cbc.ca/technology/story/2009/10/13/tech-biology-vegetarian-spider.html

Here is some more information about Bagheera kiplingi :

It is the type species of the genus Bagheera,  which includes one other species,The genus name Bagheera is derived from Bagheera, the  black panther from Rudyard Kipling's "Jungle Book."

Bagheera kiplingi is a colorful species, with the two sexes looking very different. The male has amber legs, a dark thorax that is greenish in the upper region near the front, and a slender reddish abdomen with green transversal lines. The female's amber front legs are sturdier than the other, slender legs, which are light yellow. It has a reddish brown cephalothorax with the top region near the front black. The female's rather large abdomen is light brown with dark brown and greenish markings.

The symbiotic relationship between acacia trees and the ants that live on them had been closely studied for many decades, and had long been, literally, a textbook example of symbiosis in nature.

source:http://en.wikipedia.org/wiki/Bagheera_kiplingi

The term symbiosis (from the Greek: σύν syn "with"; and βίωσις biosis "living") commonly describes close and often long-term interactions between different biological  species . The term was first used in 1879 by the Heinrich Anton de Bary,  who defined it as "the living together of unlike organisms." (source:http://en.wikipedia.org/wiki/Symbiosis).


Christopher Meehan from Villanova University spent seven years observing the spider and filming its foraging trips. He showed that the spiders are almost always found on acacia trees that are occupied by ants, for the trees only grow the tasty Beltian bodies when ants are around. In Mexico, Beltian bodies make up 91% of the spider's diet, while in Costa Rica, they make up 60% of it. More rarely, they will also drink nectar and even more rarely, they will have a meat treat by taking ant larvae, flies and even others of their own kind.


Meehan confirmed his results by analysing the chemical make-up of the spiders' bodies. He looked at the ratio of two types of nitrogen: N-15 and N-14. Plant-eaters tend to have relatively less N-15 than meat-eaters do, and sure enough, B.kiplingi's body had 5% less of this isotope than other species of jumping spiders. Meehan also considered the ratio of two carbon isotopes, C-13 and C-12. Meehan found that the vegetarian spider and the Beltian bodies had virtually identical ratios, as is usually the case between an animal and its food.
Feeding on Beltian bodies is worthwhile but far from straightforward. First, there's the problem of the bodyguarding ants. B.kiplingi's strategy is stealth and evasion. It builds its nests at the tips of the oldest leaves, where ants rarely patrol. They will actively avoid ant guards if they see them approaching. If cornered, they will use their powerful legs to leap away. Sometimes, they even drop to safety using a line of silk, hanging in midair until the danger passes. Meehan documented several different strategies, all evidence of the impressive mental skills that jumping spiders are known for.
Even if it avoids the sentries, B.kiplingi has another problem. Beltian bodies are extremely high in fibre and spiders really shouldn't be able to handle that. Spiders can't chew their food; they rely on digesting their prey outside their own bodies using venom and digestive juices, and 'drinking' the liquefied remains. Plant fibre is a much tougher mouthful and we still don't know how B.kiplingi copes with it.
Even so, it's clear that the rewards are worth it. Beltian bodies are a ready-made source of food that's available all year round. By exploiting this feast that's produced for others, B.kiplingi has become very successful. Today, it's found throughout Latin American, wherever ants form partnerships with acacias.

source: Current Biology in press


source of image:Robert L. Curry


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Thoughts worth thinking about

"Our subconscious minds have no sense of humor, play no jokes and cannot tell the difference between reality and an imagined thought or image. What we continually think about eventually will manifest in our lives."-Sidney Madwed



Laws alone can not secure freedom of expression; in order that every woman and man present their views without penalty, there must be spirit of tolerance in the entire population.- Albert Einstein Too often we underestimate the power of a touch, a smile, a kind word, a listening ear, an honest compliment, or the smallest act of caring, all of which have the potential to turn a life around. - Leo Buscaglia



A person's true wealth is the good he or she does in the world. - Mohammed



Our task must be to free ourselves... by widening our circle of compassion to embrace all living creatures and the whole of nature and its beauty. -Albert Einstein



The best way to find yourself, is to lose yourself in the service of others. - Ghandi



The unselfish effort to bring cheer to others will be the beginning of a happier life for ourselves. - Helen Keller



Aim for success, not perfection. Never give up your right to be wrong, because then you will lose the ability to learn new things and move forward with your life. Remember that fear always lurks behind perfectionism. Confronting your fears and allowing yourself the right to be human can, paradoxically, make yourself a happier and more productive person. - Dr. David M. Burns



Life is as dear to a mute creature as it is to man. Just as one wants happiness and fears pain, just as one wants to live and not die, so do other creatures. -His Holiness The Dalai Lama



Mankind's true moral test, its fundamental test (which lies deeply buried from view), consists of its attitude towards those who are at its mercy: animals. And in this respect mankind has suffered a fundamental debacle, a debacle so fundamental that all others stem from it. -



Milan Kundera, The Unbearable Lightness of Being



The worst sin towards our fellow creatures is not to hate them, but to be indifferent to them. That's the essence of inhumanity. -George Bernard Shaw

Ego's trick is to make us lose sight of our interdependence. That kind of ego-thought gives us a perfect justification to look out only for ourselves. But that is far from the truth. In reality we all depend on each other and we have to help each other. The husband has to help his wife, the wife has to help the husband, the mother has to help her children, and the children are supposed to help the parents too, whether they want to or not.-Gehlek Rinpoche Source: "The Best Buddhist Writing 2005 pg. 165

The hostile attitude of conquering nature ignores the basic interdependence of all things and events---that the world beyond the skin is actually an extension of our own bodies---and will end in destroying the very environment from which we emerge and upon which our whole life depends.