Question

how does nutiition take place in paramocieum

Answer 1

While single-celled paramecia have the ability to respond to certain external stimuli, they appear not to use that sensory system for simple navigation, new research finds. The work suggests that the ability of paramecia to navigate around flat surfaces is entirely governed by Newton's Third Law of Motion and not by active behavior. The finding, reported in Physical Review Letters, raises interesting evolutionary questions.

For such humble creatures, single-celled paramecia have remarkable sensory systems. Give them a sharp jab on the nose, they back up and swim away. Jab them in the behind, they speed up their swimming to escape. But according to new research, when paramecia encounter flat surfaces, they're at the mercy of the laws of physics.

The findings, published in the journal Physical Review Letters, come from some surprising results in research performed in recent years by James Valles, professor and chair of physics at Brown University, and his students.

The group has been working to understand how paramecia react to changes in their buoyancy. The experiments are done by adding tiny magnetic particles to the water in which the creatures swim, and then applying a powerful magnet. When the water is pulled downward by the magnet, the paramecia become more buoyant and float more easily. Pull the water up, and the creatures become less buoyant.

The initial research, published a few years ago, showed that paramecia have a remarkable ability to sense the changes in their buoyancy and adjust their swimming behavior accordingly.

"We found that if we made them sink more by making them less buoyant, they would try to swim harder against that sinking," Valles said. The effect was the same when the creatures were made more buoyant; they swam harder against the tendency to float.

But over the course of the experiments, a strange thing happened. When their buoyancy was increased, meaning the paramecia should float more easily, the creatures would eventually get stuck to the lower surface of their enclosure. When the researchers reversed the experiment, making the paramecia less buoyant, they got stuck at the top.