Fiber-Optic Wonder

Joanna Aizenberg, a scientist and one of Earth's most complex multicellular animals, entered a San Francisco store and encountered the elegant remains of Euplectella speciosa—a deep-sea sponge and one of Earth's simplest multicellular animals. Scientist and sponge might one day revolutionize fiber-optic cables, the thread weaving together our wired world.

Fiber-optic cables are basically bundled strands of optical fibers—filaments of glass and reflective cladding that transmit coded light. These fibers are crafted under high heat using expensive equipment. Because the fibers are not very flexible, the cable is hard to install and repair, and is prone to minute cracks.

The sponge Aizenberg encountered—called Venus's flower basket and other names—transmits light through resilient, flexible glass fibers made at sea temperature. Aizenberg and her colleagues aim to find out how.

Venus's flower basket is a type of hexactinellid or glass sponge whose skeleton is composed of needlelike spicules of silica. The sponge uses proteins to collect and arrange silica particles into hairlike glass fibers two to three inches long. Traces of sodium are added, making the glass fiber better able to conduct light. Organic material and concentric shells of glass encase the fibers for protection. According to Aizenberg, “You could tie [the fibers] in tight knots and, unlike commercial fiber, they would still not crack.”

This sponge lives in tropical waters and anchors itself to the ocean floor. It likely gathers luminescent (light-emitting) organisms and turns itself into a “fiber-optic lamp” to attract the plankton that it eats. Seeking protection from predators, other creatures live inside this cuplike sponge with a lattice top. Often, a mating pair of shrimp will swim in and remain for the rest of their lives.

As scientists like Aizenberg realize, connectivity means more than communication among humans. There's a sea of information to be learned when we connect with the unwired world as well.

Vocabulary

cladding:
A metal coating bonded onto another metal under high pressure and temperature.

concentric:
Having a common center.

filament:
A fine wire or thread.

lattice:
An open framework made of strips that overlap in a crisscross pattern.

spicule:
A small, needlelike structure.

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Activity

  1. Why does a fiber-optic cable contain glass filaments?
    [anno: A fiber-optic cable contains glass filaments so that it can transmit coded light.]
  2. If a fiber-optic cable were made up of filaments of black rubber, would the cable transmit light? Why or why not?
    [anno: If a fiber-optic cable were made up of black rubber it would not transfer the light because the black rubber would absorb the light instead of transmitting it along the cable.]
  3. Why are scientists interested in studying the Euplectella speciosa?
    [anno: Scientists are interested in studying the Euplectella speciosa because they are trying to replicate the structure of the sponge's filament since the filament can conduct light but also is flexible.]