Sunday, July 29, 2012

Medusa Unleashed

A Medusa is a free swimming jellyfish. Anyone who's lived near a harbor or gone to an aquarium has seen one.

The mechanical structure of a medusa is fairly simple: a slotted semi-rigid body with a ring of contractile tissue connected just above the slots. The contraction causes a "dome" structure to appear pushing water out the back and giving propulsion. Structurally, it looks pretty close to what's pictured on the left.

Except that's not a medusa.

Instead, it's a bit of silicone polymer with a ring of rat cardiac muscle.

This feat of curious engineering is the product of the ingenious minds of Janna Nawroth and Kevin Kit Parker of Caltech and Harvard.

The original paper is here. Physorg's version is here along with video of both a real medusa and the medusoid that Nawroth and Parker have built.

This is very neat stuff. It couples biological and engineering materials and is a step on the road towards real tissue and organ engineering.

It also made me thing of something interesting. Since contractile tissue (and some electrical stimulation) was all that was needed, could something similar to this have happened before? Think of it: polymer films abound in nature. Cooperative organisms (such as volvox) are also just has ubiquitous. Imagine a colony of contractile organisms who manage to adhere to a non-living flexible substrate. They get a boost in that they become more mobile. Later, the substrate becomes catalytic: it is only necessary to trigger the response. Later, still, it's not needed at all.

Cooperative life begins.

Thanks to Jim Cambias, et al, over at Science Made Cool for this one. If you don't know their site, or Jim's work, run do not walk over there.

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