The Sea Mouse and the Photonic Crystals


Aphrodita sp. (Polychaeta: Aphroditidae): marine worm with short, broad, segmented body, found in water at 1-2000 m. The entire dorsal surface, including the scales, is covered by long, feltlike threads, which produce a brilliant iridescence (Marine Life of the Channel Islands by Sue Daly). Commonly reach 15-20 cm in length, 5 cm in width. Named by Linnaeus. Their natural history is poorly known and many references actually appears to rely on a few observations only. Slow-moving carnivores, predation on large prey such as Nereis and Nephtys. Aphroditidae occurs both on soft and hard substrata as epi- or in-fauna.



When light is incident perpendicular to the axis of a spine the spine exhibits a strong red colouration (left). For off-axis incidence strong blues and greens may also be seen (right). This optical effect is unique in nature: it is the first photonic crystal found in a living system}, and much more regularly constructed than the previous example of a photonic crystal from nature (the opal).



The SEM picture of the spine (left) and a TEM picture of a subsection of the spine wall (right). The spines have the same structure as the new type of optical fibre, the photonic crystal fibre, which was first developed by the group of Professor Phil Russell at the University of Bath.



Some new images and …


Here are two high resolution photos: one of the fine hairs (left) and one of a spine (right).

a Factory for Holey Fibres (Pectinaria photos by Dr G. Rouse School of Biological Sciences, University of Sydney):


One is a juvenile specimen (left) and you can see through the head where the spines are embedded and originating. The others (centre and right) are mature specimens.

Photos by G. Rouse 2002 School of Biological Sciences, University of Sydney. All rights reserved.



Electronmicrographs


Electronmicrographs of sea mouse hairs. They show the distorted hexagonal packing of the cylindrical voids, with dislocations, rather like the patterns in foam rafts. Also shown are the wall of a hair (left) and the domain structures (right).

Close up of the internal walls. The image is taken in the plasmon region using an imaging energy filter (left). On the right is an image taken in the precarbon energy loss feature. Note the reversal of contrast.

Photos by D. R. McKenzie 2002 School of Physics, University of Sydney. All rights reserved.


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