Christian Long

Sheila Patek: Clocks the Fastest Animals

In TED Talks on April 21, 2010 at 10:14 am

Reflection by ERIN M.

Original TED page w/ speaker bio, links, comments, etc:

Sheila Patek:  Clocks the Fastest Animals

Manta shrimp make some of the fastest animal movements on the planet.

In her video, Sheila Patek talks about the exciting life of a manta shrimp. Manta shrimp are unique from other underwater animals. There are two types of manta shrimp, the spears and the smashers. The smashers, the crabs she talks about in the video, have a special limb that allows them to open shells of snails to get their food. This limb movement is indescribably fast and goes over 45 mi/hr in water. This is the fastest measured feeding strike of any animal system.

How exactly does this phenomenon happen?

Sheila Patek did the research to answer this question. Manta shrimp have a saddle shape muscle that acts as a spring to give the limb speed during the strike. This saddle shape can be more scientifically recognized as a hyperbolic surface. This unique shape is very strong. Many Architects and jewelers use this design when building because it provides a strong structure by using small amounts of material. The manta shrimp is uniquely designed to have a great amount of speed when it strikes underwater.

Speed is not everything produced by the manta shrimp’s limb. A large amount of force is also produced. Patek used a lode cell to electronically measure the forces. The measurements were taken at feeding time, the manta shrimp’s peak of aggressiveness. The forces measured in the video were very powerful compared to their body mass.

After the measurements of the forces were taken something else was discovered. There was a second peak at which the force was very powerful. Why did this second peak occur? In the video of the manta shrimp you can see a flash of light after the strike of the limb. This can be explained by cavitation. Cavitaion is the formation of vapor bubbles of a flowing liquid where the vapor pressure is lower in areas of the water.

For me, this concept was difficult to understand, but even without knowing much about this process you can see that it is very destructive. This same process is what destroys a boat propeller after many uses. These two dynamic fluid motions, the limb movement and the cavitation, can account for the two peaks of force that were measured.

The force of the limb strike is very powerful. Over time this must have an effect on the manta shrimp. Eventually the limb will get worn down. However, these animals are specially designed to molt and will grow new skin. When Patek gave her talk she also explained what occurred during the period when they cannot strike. They become very obnoxious and use there saddle shaped muscle to signal other shrimp and let them know they cannot strike to get food.

The limb of the manta shrimp was designed uniquely for its survival. Sheila Patek did an excellent job of presenting this information about the manta shrimp. There are so many things that we do not know about our world.

Who would have guessed that one of the world’s fastest animal movements came from a shrimp?


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