Physics in the animal world: sea sponges and their "optical fiber"
Crab will probably come to admire the perfect structure of the skeleton of glass sponge species Venus Flower Basket.
Sea sponges - primitive organisms. This invertebrate animals that spend almost all his life by attaching to rocks or the bottom. Sponges are found almost everywhere, from the coastal areas to the deepest parts of the ocean. Presented sponge approximately 8000 species. They do not have these tissues and organs, their functions are performed by individual cells and cell layers. They feed on sponges, banishing water through his own body. The filtrate, which lists the small creatures and various organic particles, and serve as food for sponges.
There are also carnivorous sponge - there are about 140 species. These predators feed on crustaceans and other small animals. For hunting family Cladorhizidae sponges use long sticky threads of the cellular structure. When the victim is attached to the thread, it shortens, tightens the victim to a sponge, which gradually envelops the victim and digests. Filtering water sponge is used not only for food but also to get oxygen to the body tissues. According to experts, every day many species of sponges pumped through itself the volume of water in excess of 20,000 of their own body volume. One of the most unusual species of sponges - Cladorhizidae. These creatures can be called a living optical fiber.
This sponge is a class of glass sponges (Hexactinellid) which create a basis of silica. These organisms are very beautiful, because the thread of the "skeleton" are interwoven in the most unusual combinations. Glass sponges Cladorhizidae type usually live shrimp that occupy the inner cavity of the skeleton. Shrimp larvae swim inside another, and after molting remain live inside, because to pass through a glass cell network can not. glass sponges size reaches 20-30 centimeters.
Glass sponge previously interested experts from Bell Labs. Representatives of the company, having studied fiber skeleton, concluded that the material of the structure is similar to the optical fiber. Sponges fiber length of 5-15 cm and a diameter - 40-70 microns. The structure of the fibers is complicated, they are layered objects. Centre is a rod, in fact, quartz glass. This rod is surrounded by layers of organic material and the shell. And the shell has a special structure, which allows to carry out the light on the artificial fibers.
Specialists from Bell Labs was surprised that sponges create their fibers in water at a low temperature. Man, however, produces fiber using expensive equipment at high temperatures in special furnaces. According to the expert Joanna Aizenberg, the sponge can be an example of an alternative method for the production of fiber. Moreover feature material produced sponges, is its strength and flexibility. Such fibers are much less fragile and practically do not crack. They can easily tie into a knot, the optical properties of the channel at the same time practically not be affected. Light on such fibers is going very well, because the sponge is used in the formation of the skeleton of his glass sodium ions that improve optical properties of the material. Naturally, the sodium is added by these organisms in the same conditions all the low temperature in an aqueous medium. For manufacturers of fiber optic control of sodium ions in the production process is still a problem.
At Bell Labs examined the structure of the fiber sponges, having ascertained that it consists of several layers. Optical properties of each layer are different. As mentioned above, the center optical fiber rod sponge is made of pure quartz glass. Concentric layers of glass surround the rod with the growth of the sponge. It is this structure makes the fibers formed by a sponge, very resistant to faults and fractures. The individual layers are glued together by means of a special organic glue. With the formation of the skeleton individual fibers intertwined together and form something like a lattice.
The structure of the skeleton of glass sponges have a lot in common with the structure of buildings and structures created by man. However, "building", which creates a sponge, 1,000 times smaller than most of the objects of this type, created by man. The photo shows the Swiss Tower of London, Hotel De Las Artes in Barcelona, and a structural element of the Eiffel Tower
The grille is enhanced with a special substance (mesoglea), and the skeleton of the sponge under the influence mesogloea and shell fibers becomes quite strong. According to experts, such a structure is similar to that used by architects, creating buildings in a seismically hazardous areas. Slightly deformed such material may be, but it is very difficult to break. Evolving, sponges have learned to build the strongest possible skeletons from the minimum amount of material. The researchers say that the sponge uses only as much material as you need, and nothing more.
Interestingly, the sponge type Euplectella aspergillum (already mentioned above the "basket Venus') is attached to the bottom by means of needle-elastic glass spicules having a diameter of 50 microns. Their length can reach 10 centimeters. These spicules are very strong, so break them, tearing sponge, very difficult.
In the past, scientists studying the glass sponges, conducted modeling of mechanical properties of synthetic fibers of these creatures. The aim was to find the optimal sequence of cylinders thickness for maximum strength of the skeleton in the gap. As it turned out, the design parameters are very close to reality. Sponges used reducing the thickness from the center to the edge.
Joanna Aizenberg says that the skeleton of glass sponges - one of the best solutions in mechanical engineering. Perhaps this story can help a person to open up new possibilities of materials and improved engineering design. This structure is very complex, this applies to both individual fibers and the entire skeleton in general. "It puts me in a deadlock. I can not imagine how your lips form the skeleton of the individual fibers, creating an almost perfect structure, "- said Eisenberg. Now scientists believe that the center of each fiber at its formation has a protein that plays an important role in the creation of a rod, and all the fiber as a whole.
"It's amazing how much engineering construction methods using sponges to create the skeleton" - said James Weaver, a scientist from the University of California, Santa Barbara.
Always fascinating how nature puts it's creatures together.
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