Learn more about the fascinating functions of hydrodynamic mechanisms and hydraulics in nature.

Vital Functions Of Hydrodynamic Mechanisms

Posted: December 18th, 2009 | Filed under: Extra unnatural functions | Tags: , , , , , , | No Comments »

Hydrodynamic mechanisms are also very good for dig­ging burrows. When tunnelling through moist soil, the earthworm contracts the circular muscles at its front end to the utmost. Thus, its head becomes a kind of a sharp awl (if the soil is dry the worm moistens it). Then it looks for some tiny gap between the particles of soil. If it fails to find one, the worm drives its front end into the earth by delivering blows against it from the inside with the aid of its gullet which is operated by a hydrodynamic mechanism. An increase in pressure from 2 to 14 millimetres of the water column allows it to strike blows with a force of 8.5 grams. As soon as the earthworm succeeds in burrowing itself to some depth, it increases the pressure in the front end, making it swell out and thus widen the burrow. If the soil is not very hard, the earthworm will, by repeating this operation, bury itself in the soil before our very eyes. Still more energetic are sipunculids which, when digging their burrows, develop a pressure of up to 600 millimetres of the water column.

Among the most perfect hydrodynamic mechanisms is the locomotion device found in the Echinodermata which is particularly well developed in the starfish, sea-urchins, brittle stars and various sea cucumbers. The arms of the starfish are permeated with symmetrically radiating grooves filled with a watery fluid. Small branches extending from the grooves enter each of the numerous tube feet located on the under surface of the arms. When the starfish moves, the fluid is forced into the tube feet making them swell out and stretch in the direction in which it is moving; after the tube feet get a foothold by means of the suckers on its arms their muscles contract forcing the fluid from the grooves and thus helping the starfish to crawl forward a little. Then the tube feet detach from the ground on which the starfish is moving, the fluid is forced into them again, and the cycle begins anew. This shows that the heart is not the only pump employed by nature to help the organisms of various animals in performing their most vital functions.

Fascinating Hydrodynamic Mechanisms

Posted: December 16th, 2009 | Filed under: Hydrostatic skeleton | Tags: , , , , , , | 1 Comment »

Animals can also make elective use of a hydrostatic skeleton, its main advantage being that it can be created for as long as it is needed. When it is no longer required, the pressure in the system can be reduced so that nothing remains of the skeleton. True enough, the hydrostatic skeleton is not as reliable as a bone one, and, where the supports have to be permanent, the hydrostatic skeleton has given way to more rigid constructions. But for non-permanent skeletons hydraulics has proved more advantageous. Nature has applied this invention throughout the history of the evolution of the animal kingdom, right from the lowest creatures up to the most developed ones, man included. Cavernous bodies employing blood as the working fluid is a good example.

Hydrodynamic mechanisms are still more fascinating. These range from extremely primitive devices to rather sophisticated ones. The most primitive of them include the excretory siphon-tube in bivalve mollusks. These living crea­tures derive oxygen and food, microscopic organisms and particles of plant and animal matter from the surrounding water, which they suck into the mantle cavity. The water saturated with carbon dioxide and polluted with excretory products is ejected through a special siphon-tube. The mollusk, no doubt, wishes the waste material to be removed far away from its body so that it would not return into its mantle cavity. This explains why the excretory siphon-tube is rather long, though it has no special muscle and cannot stretch. When the shell is closed and water stops moving into the mantle cavity, the siphon-tube con­tracts, but as soon as the fluid resumes its flow, the siphon straightens and stretches.

The hydrodynamic (water-vascular) mechanisms in the spider’s legs are concerned with locomotion. These eight-legged creatures whose legs consist of six or seven segments flex them, like all animals do, by contracting certain specific muscles, but extend them by increasing pressure within the chitin-clad legs.