Factoid Friday – Glowing Neon Tetras
October 2nd, 2009 |
Neon tetras (Paracheirodon innesilich) are a popular aquarium fish that appear to have a glowing horizontal stripe along their side. This stripe is iridescent and is incapable of glowing in the absence of light. Iridescence is caused by the reflection of light off of the many transparent layers attributing different refractive indexes.
It has been studied that the colour of the stripe changes under differing conditions (see article here). The tetra’s stripe is violet or blue when under dim-light conditions. But when exposed to more intense light the cytoplasm of the cells within transparent layers thicken so that longer wavelengths are emitted creating a green colour. It is thought that the layers contain a rhodopsin-like molecule (which our eyes have) to induce the thickening of the cytoplasm through osmotic processes via sodium channels.
