Bolinopsis and the Photonic Crystals
Image ID: nur01004,
National Undersearch Research Program (NURP) Collection
In a recent paper we have also investigated the origin of the iridescence
of the tentacles of the jellyfish
We found that once again this marine creature exploits a photonic crystal to achieve its colour effects.
This time, the crystal has low symmetry, with the unit cell being a parallelogram.
The result of this low symmetry is that the optical properties of the tentacles are strongly dependent on direction.
For incidence on the long side of the unit cell, the reflectance peaks are sharp and frequent, tending to form a comb
spanning the visible region.
The result would be a white flash of light from this direction.
For incidence on the shorter side, there are fewer peaks, located in the red, green and blue regions.
This would give clear iridescence, of the sort evident in some
images of Bolinopsis.
Others tend to show white flashes of
light in the tentacle region. We speculate that Bolinopsis is able to drape its tentacles
either to display strong colouration as a warning signal, or to give white flashes resembling the
fluctuating light due to reflectance off waves just above it.