Vegetarian spiders

We all know that spiders eat insects, or the occasional bird or small rodent, but it now appear that there exist a breed which is vegetarian, or at least partly vegetarian.

The 60-Second Science podcast over at Scientific American has more on this: Odd Spider Prefers Salad

Scientific American also has an article about the subject

Unusual Spider Species Passes Up Live Prey for Plants

Of the 40,000-plus spider species known, only a few nibble on plants—typically, as a dietary supplement of nectar or simply as an accidental ingestion of pollen. A new paper, published online today in Current Biology, details the natural history of Bagheera kiplingi, a jumping spider that has vegetarian leanings, and its interesting arrangement with a plant and the ants that protect it.

Certain acacia plants (Vachellia collinsii) and ants (Pseudomyrmex peperi) have developed a mutually beneficial arrangement. The plant provides hollow areas for the ants to nest, along with nutritious nuggets, called Beltian bodies, for them to eat. For their part, the ants help to fend off would-be plant eaters. The crafty B. kiplingi, however, has thwarted the system—also feasting on the plant while managing to outmaneuver attacking ants.

It's not known why the spiders prefers to eat the less nutritious plant leaves to other prey, but interestingly enough, the behavior of the spiders while the hunt is the same as it would have been if it was more traditional prey

Despite their unusual meals, these spiders still exhibit some more traditional hunting behavior. "They're like miniature cats," Meehan says. "They literally stalk and hunt the plant,"

I can't help smile at the thought of a spider stalking a plant.

The original study is behind a paywall, but can be found here.

National Geographic also writes about the spider: "Surreal" Vegetarian Spider Found -- A First

Evolution is not random

We all know that a lot of people misunderstand the concept of evolution, and believes it to be random ("pure chance"), but this is not what the theory states at all.

Now, a new international study shows that the theory is right, and evolution is not random.

Via ScienceDaily:
New Findings Confirm Darwin's Theory: Evolution Not Random

According to Darwin’s theory of evolution, individuals in a species pass successful traits onto their offspring through a process called “deterministic inheritance.” Over multiple generations, advantageous developmental trends – such as the lengthening of the giraffe’s neck – occur.

An opposing theory says evolution takes place through randomly inherited and not necessarily advantageous changes. Using the giraffe example, there would not be a common neck-lengthening trend; some would develop long necks, while others would develop short ones.

Now, the findings of an international team of biologists demonstrate that evolution is not a random process, but rather occurs through the natural selection of successful traits. The collaborative study by researchers at the Technion-Israel Institute of Technology in Israel, the U.S, France and Germany is published in the November 2007 issue of Current Biology (vol. 17, pp. 1925-1937).

To settle the question about whether evolution is deterministic or random, the researchers used various tools – including DNA strand analysis and electronic microscopy – to study female sexual organ development in 51 species of nematode, a type of worm commonly used to better understand evolutionary processes.

The findings showed similar development in the species, which falsifies the idea that the development is random.

The Current Biology article about the study, can be found here:
Trends, Stasis, and Drift in the Evolution of Nematode Vulva Development. It's quite technical, and much of it went over my head. Still, it's worth taking a look at.