The colors of an octopus that has not been bothered
Most of the time the rings are faint. The resting palette is sand, ochre, and a low yellow, with texture doing as much work as color.
Read the noteBlue that is built, not dyed
Iridophores make color the way a film of oil does, by structure. That is why the rings seem to glow rather than sit flat on the skin.
Read the noteHow the rings switch on
The blue is structural color, uncovered by muscle in about a third of a second. Dark pigment around each ring makes the contrast.
Read the noteA name from the Bay of Bengal
Hapalochlaena nierstraszi was described from one specimen in 1938. A second was reported off Chennai in 2013.
Read the noteThe octopus that draws lines instead of rings
Hapalochlaena fasciata, the blue-lined octopus, lives in shallow water along eastern Australia and warns with stripes.
Read the noteThe southern blue-ringed octopus
Hapalochlaena maculosa lives along southern Australia and Tasmania, deeper than its tropical relative and studied more closely for the way it mates.
Read the noteThe greater blue-ringed octopus
Hapalochlaena lunulata is the tropical species, with larger rings and a range that runs from Sri Lanka to the western Pacific.
Read the noteFour named species, and a list that is still open
Hapalochlaena was named in 1929. Four species are confirmed, and taxonomists still have unnamed animals in view.
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