Blue Bottle Jellyfish

Despite being labelled as a jellyfish, physalids are actually siphonophores, compositions of colonies. Physalia captures prey using venomous nematocysts which shoot out stinging barbs when the cells are disturbed. They appear translucent blue when alive, but unfortunately due to death and method of preservation this one has lost its brilliant colour. I value this specimen because of its preparation.

Great care would have been taken to collect and preserve it as, even when dead, physalids remain venomous. The techniques of preservation used here help to display the natural form. This has been done using glass floats attached to the pneumatophore (the individual polyp at the top, a gas filled ‘balloon’) which replicates the natural position of the specimen in the sea. This also helps to show the length of the tentacles. Without fluid preservation it would be almost impossible to use invertebrates such as this for educational purposes. This method of preservation captures not only the specimen but the development of techniques used over many years incorporating scientific and educational values together. This specimen is just one of approximately 25,000 jars of fluid preserved specimens in the Museum’s collections.

Kate Pocklington, Museum Conservation