After seeing kwasi's cockatoo shrimp I noticed the Living Lights exhibition which is part of Edinburgh’s Science Festival. Photographs reveal how the emission of light by living organisms is used for a variety of reasons including to attract mates, prey or to repel predators and now scientists are researching how bioluminescence and fluorescence may be used in different ways in medicine and design etc.

These are called sea pens because they resemble writing quills or feathers. In Britain there are three species of sea pens but this one is the phosphorescent sea pen (Pennatula Phosphorea) When it is disturbed it emits a blue green light spreading out in waves towards its extremities. This type is usually about 40 cms high but sea pens can grow to between 5 cms and 2 meters.

Unfortunately few of us who are not divers will see these in their natural state.