Some effects of mechanical agitation on Paramecium caudatum

SAUV-A Bio-Inspired Soft-Robotic Autonomous Underwater Vehicle

Autonomous and remotely operated underwater vehicles allow us to reach places which have previously been inaccessible and perform complex repair, exploration and analysis tasks. As their navigation is not infallible, they may cause severe damage to themselves and their often fragile surroundings, such as flooded caves, coral reefs, or even accompanying divers in case of a collision. In this study, we used a shallow neural network, consisting of interlinking PID controllers, and trained by a genetic algorithm, to control a biologically inspired AUV with a soft and compliant exoskeleton. Such a compliant structure is a versatile and passive solution which reduces the accelerations induced by collisions to 56% of the original mean value acting upon the system, thus, notably reducing the stress on its components and resulting reaction forces on its surroundings. The segmented structure of this spherical exoskeleton protects the encased system without limiting the use of cameras, sensors or manipulators.

Poly(ethylene oxide), a new slowing agent for protozoa

The water-soluble, viscoelastic resin Polyox WSR 301), a poly(ethylene oxide) of high molecular weight (approximately 4 million) is introduces as a new slowing agent for protozoa. Generally, as the kinetic viscosity of the resin increased from 0.25% to 1% (w/v), the swimming velocity of Euglena gracilis, Didnium nasutum, Paramecium aurelia, Blepharisma undulans, and Prorodon platyodon decreased. The 1.0% solution had the highest viscosity and decreased velocity more effectively than 1.0% methyl cellulose and Protoslo solutions. The Polyox solutions differed from those of methyl cellulose and Protoslo by having, in addition to viscous drag, an elastic recoil that pulled the protozoa backwards when their swimming efforts stopped. The toxicity of these slowing agents was determined using 10 P. aurelia/test slide preparation. Paramecium numbers decreased in 1.0% methyl cellulose and Protoslo to nearly zero by 24 hr; in Polyox, not only were most these ciliates alive after 24 hr, but many survived for 96 hr and divisions occurred in 0.25% and 0.50% solutions.