I don't mean slow gentle transitions like a chameleon, but quick pulses, rapid waves of colour that literally flow over the body and then down the arms. Brown becomes white, stripes change to patches, turquoise alternates with emerald. Shifts in hue as subtle as flickering candlelight play on top of dramatic rock-concert style colour changes. Even their normally velvety smooth skin gets involved, going from smooth to wrinkled to knobby, barely keeping pace with the colours. An octopus wears its emotions on its sleeve and a really excited octopus can cycle through its colours so fast that it's hard to believe you're not imagining it.
Divers often find octopuses by locating the litter of shells that line the entrance to their dens.
After mating, the female retreats to her den and lays scores of eggs. She tends them continually until they hatch, whereupon she expires, succumbing to starvation and exhaustion. Some are brilliant yellow, while others are painted with an outrageous pattern of stripes and dots that clash with the equally garish tufts on the animal's back. Most are less than two inches long and can sit comfortably on the tip of your finger. And since form does indeed follow function, nudibranches also demonstrate some of biology's most ingenious adaptations.