A rare sight at Gili – on Christmas morning hundreds of beautiful button-like blue creatures washed up on the beach. Initially, everyone was concerned since the creatures resembled jellyfish. However, after a brief investigation by our marine biologist, everyone was reassured – these are harmless Blue buttons (Porpita porpita). These animals are not true jellyfish, in fact they are colonial hydroids. Porpita is actually a colony of organisms, composed of many orderly arranged individual polyps, which are specialized for different functions. Some polyps form the chitinous float which keeps the blue button on the surface, others form prey catching tentacles, serve digestive or reproductive functions.
The central float of a blue button can be up to 4 cm wide, surrounded by vivid blue tentacles. Although blue buttons are not dangerous for swimmers, they belong to phylum Cnidaria, and characteristically still have stinging cells by which they catch their prey. For sensitive individuals, contact with them (just like contact with a coral, which is also a cnidarian) may cause minor skin irritation, but overall these are considered ‘swimmer safe’! However, unless you have specialist knowledge, we would strongly advise you never to touch any marine life unless you are sure what it is and what it does or doesn’t do; especially when it comes to jellyfish-like creatures.
Later in the afternoon, our beautiful treat disappeared almost as quickly as it arrived; the northerly wind that brought hundreds of these creatures to our beach took them further on their journey, leaving just a few individuals stranded on the beach for our guests to wonder at.
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| Porpita porpita in a glass… |