Octopus & Squid

Cuddly creatures with more than two arms

Cuttlefish are capable of changing colour and pattern (including the polarization of the reflected light as well as the texture of the skin.

Cuttlefish can go into electric stealth mode

Sharks home in on faint bioelectric fields generated by the bodies of their prey which they pick up using sensitive detectors on their snouts.

When researchers from Duke University showed captive cuttlefish held in tank videos depicting the menacing silhouettes of a shark or predatory grouper fish they reacted by lowering the electric field dramatically. Being shown the shadow of a harmless crab produced no reaction.

Octopuses observed throwing silt, shells and algae around and at other octopuses

In 2015 and 2016, researchers observed and filmed instances in which gloomy octopuses (Octopus tetricus) in Jervis Bay, Australia threw debris around themselves and sometimes at other octopuses.

This was the first time such throwing behavior has been observed in octopuses.

What was going on? Were these intelligent creatures merely rough-housing or having a pillow fight?

Giant Pacific Octopus - photo by Andrey Bizyukin
Giant Pacific Octopus interact with divers

Do octopuses have an emotional life?

Octopuses have intrigued scientists for years, because they have both long- and short-term memory, they remember solutions to problems, and they can go on to solve the same or similar problems. They have been known to climb aboard fishing boats and open holds in search of crabs. They can figure out mazes, open jars, and break out of their aquariums in search of food.

The 12cm (4.72inch) fossil that caught the eye of palaeontologist Christopher Whalen.
The 12cm (4.72inch) fossil that caught the eye of palaeontologist Christopher Whalen.

Overlooked fossil turns out to be oldest known ancestor of octopuses

Found in Montana’s Bear Gulch limestone formation, the unassuming 12cm (4.72inch) fossil was subsequently donated to the Royal Ontario Museum in 1988. And there it lay quietly in a drawer in the Invertebrate Palaeontology collection for decades while scientists fussed over fossil sharks and other creatures from the site.

Until, one day, palaeontologists noticed the fossil’s 10 limbs and took a closer look.

Octopus at Curacao
Octopus on reef, Curacao

Octopuses’ arms can detect light

In general, the cephalopod’s sense of where its body is in space is quite poor, so this complex instinctive behavior may act to protect the arms from undetected predators nearby, which may mistake the tips of the octopus’s arms as fish or worms.

That octopus arms react to light has long been known. Its skin is covered in chromatophores, pigment-filled organs that change color when light falls upon them. They are behind the octopus’s color-changing camouflage ability.

Cephalopods’ colour-changing skin inspires shape-changing gel

Inspired by this, the engineers at Rutgers University–New Brunswick have developed a 3D-printed smart gel that changes shape when exposed to light, as well as a 3D-printed stretchy material that can reveal colours when the light changes.

A paper on the research has been published in the journal ACS Applied Materials & Interfaces.

Octopuses are highly intelligent creatures.
Octopuses are highly intelligent creatures.

Octopuses seen punching fish

Called "active displacement" of fish, this behaviour usually takes place during collaborative hunting efforts that both the octopus and fish engage in.

In such a situation with multiple parties, a complex network is created where investment and payoff can be unbalanced, and this gives rise to partner control mechanism, said marine biologist Eduardo Sampaio from the University of Lisbon in Portugal. A paper on this behaviour was published in the Ecology journal.

Octopuses that live deeper in the ocean have bumpier skin

Scientists from the Field Museum in Chicago, USA recently discovered that Pacific warty octopuses don’t all have the same appearance, nor do they all live at the same ocean depth.

Their findings, which was published in the Bulletin of Marine Science, indicated that the bumpier the octopus’ skin was, the deeper in the ocean they would be found.

Southern California's Market Squid Run

Most years, Southern California on the US west coast is the site of a special marine life aggregation, treating locals to one of the most unique dives in the world. Hundreds of thousands of market squid (Doryteuthis opalescens) swim into recreational dive depths to mate and lay an expansive canvas of egg baskets (collections of eggs) across the sandy substrate.