Do we look like aliens to an octopus?

Paul the Octopus shot to fame when he was used to predict World Cup winners in 2010. How intelligent are these creatures? Dr Anjani Ganase explains in this creature feature.

Cephalopods (head-foot)

The group of marine creatures that includes squids, cuttlefish and octopus are in a family called cephalopod, which literally translates head-foot. Most cephalopods look as if they completely lack a body.  The basic anatomy of a cephalopod consists of a mantle (the head), a siphon or funnel for propulsion, two large eyes and eight tentacles. While some cephalopods have internal structure or bone, such as squid and cuttlefish, octopuses lack any bones or skeletal structure and as a result are extremely flexible and capable of morphing to fit through tight spaces. Conversely, the nautilus, which is a distant cousin, has a more rigid shape because of its large, external coiled shell. The shell features a series of chambers that can be filled with air/ gas and used as ballasts to control their buoyancy and aid in swimming. Squid and cuttlefish also have two additional tentacles to assist in prey capture from a greater distance, while octopuses have an incredible range of motion with eight arms. The many arms can wrap around the prey in a tight grip. This is made even more secure by the series of suckers and hooks found along the arms and tentacles. To aid in feeding they also have a hard beak for biting and tearing. Cephalopods move mostly through propulsion of water through a siphon. These propulsions always make them look like they are backing away. While octopuses can propel quickly away when necessary they also crawl, climb and walk along the bottom. 

Coconut crab using a coconut shell and a shell in East Timor. Photo by Nick Hobgood (CC BY-NC-SA 3.0CC)

The eyes of cephalopods are extremely unusual in shape and function. They each have uniquely shaped pupils, for example octopuses have rectangular pupils, squid have a circular shape and the cuttlefish have a W shaped pupil. Scientists have noted that the shapes of the pupils do adjust and change shape with light intensity, similar to the aperture of a camera. This allows them to see in a wide range of light. The W shape of the cuttlefish is thought to be able to detect polarised light and the angle and direction of its origin. This reduces the underwater glare that may affect their vision. However, despite being able to detect subtle changes in light intensity and direction, cephalopods are thought to be colour-blind.

Not so central intelligence

Cephalopods are considered to be intelligent beings as they have a well-developed neural system. Humans have about 200 billions neurons and octopuses have roughly 200 million, which puts them on the same level as dogs. However, while humans have a central nervous system with our brains carrying most of our neurons, cephalopods, such as the octopus, have a decentralized nervous system with a significant portion of neurons spread throughout its body and arms. This allows them to “think” in a very different manner to us. Owing to the decentralisation, the octopus’s arms appear to act autonomously for certain activities. Hunting and hiding will trigger certain behavioural responses in different parts of its body independently. This type of thinking is alien to us as there are very few actions that occur without a decision-making strategy carried out by the human thought process. Cephalopods were thought to be the first intelligent marine organisms, capable of problem solving, such as unscrewing a cap, escaping the confines of their tank and using tools for protection. The coconut octopus in Indonesia famously uses coconut shells to enclose itself to avoid getting eaten. Despite being solitary creatures, octopuses are also keen observers and are capable of learning from mistakes made by others. 

Camouflaging cuttlefish. Wikimedia commons

Masters of disguise

By far the most intriguing skill of cephalopods is their ability to change  colour, shape and texture to blend into any background to avoid being caught or to capture prey. Different patterns can be expressed in different parts of the body at will to express friendly or defensive traits to friend and foes at the same time. Cuttlefish can rapidly change patterns to resemble flashing lights for signalling during courting and defensive occasions, and even to hypnotise prey. The pharaoh cuttlefish can adjust colour texture to resemble a hermit crab to appear harmless to neighbouring prey, while also appearing to have a hard shell to deter predators. Octopuses also use the ability to change their skin to mimic other animals. The mimic octopus of Indonesia, for example, can morph to look like a flatfish; it can bury itself partially into the sand and use two of its arms to mimic a venomous sea snake, it can even mimic a lionfish when it swims in the water column, using its banded arms to resemble the banded spines of the lionfish. In all, the mimic octopus can mimic up to 15 other animals and there are certain mimics that make even scientists scratch their head in wonder. Some species of cephalopods can even emit light from bioluminescence as another form of camouflage. Knowledge in camouflaging strategies of cephalopods have been utilised in many applications including military strategies.

Despite all the tactics used by cephalopods, they are most famous for inking in really stressful situations. As their last line of defence, cephalopods can release a cloud of black ink to act as a smoke screen for a quick escape. Some ink may also be toxic or act as an irritant.

Learning from life in the ocean

It is thought that the ancestors to cephalopods appeared on the earth over 500 million years ago, far longer than humans have been around. In this age when humans are beginning to respect and work to preserve all life on earth, what should we learn from creatures that have occupied and survived on planet ocean? For one thing, we begin to understand that intelligence is demonstrated in many more creatures than we might be willing to accept. And controlling intelligence may not only reside in the brain or be the only way to progress. A rigid structure is a hindrance when flexibility and change are needed. Shape-shifting and disguise are worthwhile skills to develop. Most of all, humans are inextricably connected to the stuff of life everywhere: how should we acknowledge and use this understanding?

Camouflaging Octopus by Thomas Peterson (CC BY-NC-SA 2.0CC)

Reference:

https://ocean.si.edu/ocean-life/invertebrates/cephalopods