Replies to This Discussion

Permalink Reply by doone on June 4, 2012 at 5:30pm

From WA http://blog.wolframalpha.com/2010/10/28/exploring-earths-history-wi...

Soft-bodied animals such as worms started to appear on the sea floor during the Ediacaran Period, 635 million years ago, and around 542 million years ago, life started to exhibit a more “shelly” appearance. The fossil record shows an “explosion” of life forms during the Cambrian period. Many strange creatures that would look alien to us today developed during this time period. For example, Anomalocarids, such as the one shown in the following animation, were among the top predators.

Before the Ordovician Period, the only living creatures could be found in the sea. Meanwhile, life continued to evolve into forms more like those we know today. Fish were abundant during the Devonian Period, around the same time that arthropods were making their first significant excursions onto land.

Permalink Reply by Adriana on June 4, 2012 at 5:31pm

I love that animation of Anomalocarid!

Permalink Reply by Michel on June 4, 2012 at 5:50pm

Good question, great answer =)

Permalink Reply by Davy on June 5, 2012 at 5:15pm

That answer is the reason why I doubt that somewhere out amongst the stars there is an intelligent life form that its form is based on a insectiod body pattern, due to their system of oxygen intake. Which would exclude them from some of the severe environments such as high altitudes.

Humanoids on the other hand is another matter as they can survive in a large range of differing environments.

Permalink Reply by Adriana on June 5, 2012 at 5:17pm

True. Hollywood likes giant insects as aliens because they look so damn scary. 

Permalink Reply by doone on June 6, 2012 at 9:32am

Another Reason of Small Body Sizes

Mosquitoes fly in rain thanks to low mass

http://www.sciencedaily.com/releases/2012/06/120604155558.htm

June 6, 2012

ScienceDaily (June 4, 2012) — The mosquito is possibly summer's biggest nuisance. Sprays, pesticides, citronella candles, bug zappers -- nothing seems to totally deter the blood-sucking insect. And neither can rain apparently.

Even though a single raindrop can weigh 50 times more than a mosquito, the insect is still able to fly through a downpour.

Georgia Tech researchers used high-speed videography to determine how this is possible. They found the mosquito's strong exoskeleton and low mass render it impervious to falling raindrops.

The research team, led by Assistant Professor of Mechanical Engineering David Hu and his doctoral student Andrew Dickerson, found that mosquitoes receive low impact forces from raindrops because the mass of mosquitoes causes raindrops to lose little momentum upon impact. The results of the research will appear in the June 4 issue of the Proceedings of the National Academy of Sciences.

"The most surprising part of this project was seeing the robustness this small flyer has in the rain," Dickerson said. "If you were to scale up the impact to human size, we would not survive. It would be like standing in the road and getting hit by a car."

What the researchers learned about mosquito flight could be used to enhance the design and features of micro-airborne vehicles, which are increasingly being used by law enforcement and the military in surveillance and search-and-rescue operations.

To study how mosquitoes fly in the rain, the research team constructed a flight arena consisting of a small acrylic cage covered with mesh to contain the mosquitoes but permit entry of water drops. They used a water jet to simulate rain stream velocity and observed six mosquitoes flying into the stream. All the mosquitoes survived the collision.

"The collision force must equal the resistance applied by the insect," Hu said. "Mosquitoes don't resist at all, but simply go with the flow."

The team also filmed free-flying mosquitoes that were subjected to rain drops. They found that upon impact the mosquito is adhered to the front of the drop for up to 20 body lengths.

"To survive, the mosquito must eventually separate from the front of the drop," Hu said. "The mosquito accomplishes this by using its long legs and wings, whose drag forces act to rotate the mosquito off the point of contact. This is necessary, otherwise the mosquito will be thrown into the ground at the speed of a falling raindrop."

To view a video on this research, click here: http://www.youtube.com/watch?v=LQ88ny09ruM&feature=youtu.be

Share this story on Facebook, Twitter, and Google:

Other social bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by Georgia Institute of Technology, via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

1. Andrew K. Dickerson, Peter G. Shankles, Nihar M. Madhavan, and David L. Hu. Mosquitoes survive raindrop collisions by virtue of their low mass. Proceedings of the National Academy of Sciences, June 4, 2012 DOI:10.1073/pnas.1205446109

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

Free-flying mosquitoes can survive the high-speed impact of falling raindrops. High-speed videography of those impacts reveals a mechanism for survival: A mosquito's strong exoskeleton and low mass renders it impervious to falling drops. (Credit: Image courtesy of Georgia Institute of Technology)