Another beautiful jellyfish, the crystal jelly (Aequorea victoria), is normally almost perfectly clear but when disturbed it illuminates its outer bell in a blue-green glow using tiny light producing organs.

The light producing substance harvested from these guys is aequorin, a calcium-activated photoprotein used in medical research. The crystal jelly is also the very same creature who’s genes have been inserted into mice to make them glow green as their genetically modified bodies produce their own aequorin.

As the water here off the coast of Kerry is still getting warmer I’m looking forward to these guys being around for a few more months yet.