The Exploration Vessel (E/V) Nautilus has brought us deep-sea glimpses of some amazing marine life: diving sperm whales, tenacious cephalopods, bizarre purple "jello balls" and, just this July, a shiver of sixgill sharks down in the depths off California's Channel Islands. Their latest offering comes in tiny and spellbindingly translucent form:
Cockatoo squid, more formally known as members of the genus Taonius, are typically found at depths of around 300 metres (900ft). This particular individual (Taonius borealis) was spotted during a recent dive over Quinault Canyon, part of the NOAA's Olympic Coast National Marine Reserve, which lies off Washington state.
"When we first saw it, it was pretty transparent, and then the chromatophores lit up and it became spotted as we got closer," explains the Nautilus team.
Much like the chromatophores found in the skin of octopuses and other cephalopods, these tiny, pigment-carrying cells allow the cockatoo squid to change colour and reflect traces of light. To help it blend in against an inky deep-sea backdrop, the squid's cells are tuned to display red: a colour of light that doesn't penetrate the ocean's depths. To would-be predators, the red colouration is invisible. This crimson camouflage is used by many species that inhabit the so-called "twilight zone", like the bloodbelly comb jelly:
"The only organ that is clearly visible in these squid is a cigar-shaped digestive gland – which is basically the equivalent of the liver," adds the team. "They hold it in the vertical position to reduce its silhouette." Around the organs, ammonia solution keeps the squid's balloon-like body inflated, and helps it maintain buoyancy.
The anatomical feats don't stop there, though: cockatoo squid can also move their googly eyes independently (which comes in handy when both predators and prey can come at you from all sides).