With a little help from my friends…

The rusty glow of a blooming marine phytoplankton, Oxcillatoria erythraea, can be startling when an entire bay is covered by what is commonly known as the “red tide.” More subtle bluish bioluminescence can be seen with the gentle disturbance of the ocean surface colonised by the phytoplankton, Noctiluca. But sometimes, pelagic bioluminescence can be more than merely curious. Certain pelagic animals are known to cooperate with prokaryotes to use this ethereal light for defensive purposes.

The Pacific bobtail squid, Euprymna scolopes, is born having an empty bilobed sac within the centre of its mantle cavity. Shortly after the squid hatches, its sac is colonised by a Gram negative rod, Vibrio fischeri, a luminous bacterial symbiont selected by the squid for this purpose. V fischeri is the only bacterial species capable of colonising a normal light organ in this squid. Ciliated cells on the ventral surface of the squid beat, passing seawater over and into the pores of this organ. Apparently, the ciliated epithelial cells produce mucus that can be used to …