Between five and ten centimetres in length, the Hawaiian bobtail squid is a tiny hunter that stalks its prey at night in shallow coastal waters. Although it has a unique luminescent organ, unlike other squid species, the squid cannot change colour at will, so it spends the day buried in the sand, only coming out at night to hunt for food. But when ultraviolet light is shone on the eighth coin in the Luminous Marine Life series, its colour changes from light brown and black to red or blue.

Located in the cephalopod’s mantle, the luminescent organ of the Hawaiian bobtail squid is powered by bioluminescent bacteria, with which the squid has an extraordinary partnership of convenience. The bacteria produce light and in return the squid provides them with shelter and food in the form of a sugar-amino acid solution. When the bacteria begin to glow, the silhouette of the squid disappears in the light coming from above, and when viewed from below, it can no longer be distinguished from the glittering surface of the water, for example, when lit by moonlight.

Cephalopods, especially octopuses, are intelligent animals and their many abilities fascinate visitors to aquariums where it has been show that they can solve tasks such as opening cans, completing puzzles correctly and even operating a camera.

All 12 of the magical sea creatures in the Luminous Marine Life series are shown in silhouette on the coin’s obverse. Air bubbles up between them and a tail fin disappears beneath the waves to the right. On the coin’s reverse, a wide band, reminiscent of an old-fashioned porthole frames an aquatic scene that features a mauve stinger in the centre. An island with palm trees can be seen above the surface of the water. When the coin is illuminated with ultraviolet light, the jellyfish glows and changes colour, so that the light brown of its bell turns blue or red, as does the pinkish purple of its tentacles and oral arms.