Cephalopods - princes of darkness
Extracted from The Sea that Never Sleeps by Douglas David Seifert, read the full feature in the DIVE night diving special
Of all the animals that are active at night, the true royalty of the nocturnal kingdom are the cephalopods – the squid, cuttlefish, octopus, dumpling squid, bottletail and bobtail squid.
These animals do their most effective hunting at night, when their soft bodies are the least exposed to predation risk.
Their eyesight is remarkable, even in the dimmest light, and they are able to see spectra impossible for the human eye to perceive. Their senses of touch and chemoreception are utilised in synergy as effective tools, in concert with a highly intelligent, problem-solving brain.
The diminutive pyjama squid (Sepioloidea); bobtail squid, also known as dumpling squid (Sepiolida) and the bottletail squid (Sepiadarium) are small cephalopods, rarely reaching 10 cm in length and actually more closely related to cuttlefish than to squid.
They have disproportionately large eyes and use their ten arms to bury themselves beneath the sand and rubble by day emerging to hunt at night. Under cover of darkness they emerge from the substrate and roam across the bottom, their large eyes wide and their pupils fully expanded to take advantage of their exceptional eyesight in the dimmest of conditions. They hunt small crustaceans and fish but if a light shines over them, they instantly try to blend in with the bottom by changing their coloration via chromatophore pigments in their skin, as well as very rapidly trying to bury themselves just below the substrate so that only their eyes are above the surface.
It has recently been determined that the Berry’s bobtail squid (Eupryhna berryi) carries the same lethal toxin as the blueringed octopus (Hapalochlaena), and also the flamboyant cuttlefish (Metasepia pfefferi), two cephalopod species perpetually active by night as well as by day – apparently, if you carry enough lethal venom, you can go about your business regardless of whatever time of day or night.
Perhaps the most beautiful of all the nocturnally-active, soft-sediment retiring cephalopods is the starry night octopus (Octopus luteus), a long-armed octopus with a brilliant colouration, rivalling the fascinating patterns of its long-arm octopus cousins the mimic octopus and the wonderpus, which also take advantage of night for more liberal hunting strategies out in the open.
Very shy of any light, the starry night octopus is bright crimson, covered in white spots, and can be found prowling the sediment, sand or mud plains in search of bivalves and crustaceans.
Ounce for ounce, pound for pound, the most powerful and ruthless creatures in the sea are the squid.
Although reclusive and shy, somewhat flighty by day, squid are the cheetahs of the night sea. They are able to manoeuver rapidly and are capable of great bursts of speed. They may leave a would-be predator confused in a cloud of ink if attacked, or catch and rip apart any of its prey without uncertainty from the moment of targetting that prey.
With ten arms and tremendous strength, squid are a force to reckoned with. They are known to attack, kill and cannibalize their fellow hunters should they become injured.