The friendly octopus

Octopuses

“Octokisses” by Anna-Karin Bergkvist 2016. Watercolour on paper.

In the 2010 discovery documentary “Aliens of the deep sea”, the narrator questions why octopuses, despite being highly intelligent, yet has not evolved to become as (or more) intelligent as humans. As the title of the documentary suggests, octopuses are so different from us that they are practically aliens. Even so, the most fascinating thing about them is maybe not how different they are from us, but how similar. Scientific studies on different species of octopus have shown that they can use tools, solve difficult puzzles and even learn by watching other octopuses. So why have they not started to build high-tech cities under the sea yet? Well, one reason might be because most octopuses are grumpy Squidwards who hate their neighbours.

Even though octopuses can learn to solve problem by watching others, they tend to be solitary and stay away from others in the wild. Even when mating, they prefer to stay at (literally) an arms length from each other. They do have a very good reason for this though, as most octopuses don’t hesitate to eat other members of it’s species if they get the chance. Because octopuses don’t engage much in social interaction, it is actually quite surprising that they are so intelligent. So what if octopuses were more social, would they become even more intelligent? In fact there is one octopus that just might be the start of a new trend in octopus evolution:

The Larger Pacific Striped Octopus

Observing and recording the incredibly unique cohabitation, hunting, and mating behaviours of this fascinating octopus was beyond exciting – almost like watching cryptozoology turn into real-life zoology.

Richard Ross, senior aquarium biologist and cephalopod expert from the California Academy of Sciences.

Despite it’s name, this octopus doesn’t get much bigger than an apple, about 7 cm for females and 4.5 cm for males. In the media, this octopus has been referred to as “the social octopus” or even “the romantic octopus” because it has some quite unique ways of doing things. It was actually described already in 1977, but the results of the study seemed so bizarre that nobody would believe it. It was not until another study was published 2015 that the original observations were confirmed. This little octopus belongs to a family of octopuses called harlequin octopuses, because it has contrasting stripes and dots all over it’s body. Like many other octopuses, it can also change colours, from pale white to a dark reddish brown. Biologists believe that is this colour changing ability might be used as a tool for social interaction, because, unlike other octopuses, the Larger Pacific Striped Octopus actually likes to hang out with others.

Good neighbours

Instead of living alone far away from any neighbour, the LPSO have been found to live in colonies of up to 40 individuals. The octopuses lives in dens made old shells or hollow rocks, in water between 40 and 50 meters deep. Mating couples are even more close, and sometimes share a den for several days. They even share food with each other (getting dangerously close to each others sharp beaks) and do housework together (as in cleaning out the den).

Passionate lovers

When octopuses mate, the male inserts his specialised mating arm into the mantle of the female through one of her siphons. Normally, a male octopus would try to stay as far away as possible when doing this, to avoid getting eaten by the female (who usually is larger). The LPSO however, mate beak to beak, with their arms entangled around each other in a close embrace. (When mating, the female usually takes on a pale white colour, while the male becomes dark.) From our human perspective, this close cuddling might be interpreted as romantic and affectionate. It might not be quite as romantic as it looks though, according to some of the theories about why the LPSO have developed this behaviour. One theory is that since the females can mate with more than one male, the male holds on to her to prevent any other male from getting close. Another reason might be that the face-to-face position allows the female to stay close to her eggs, which leads us to yet another unique quality of the LPSO:

Dedicated parents

Usually, a female octopus only lays eggs once in her life, after which she goes into what is called senescence, when she will stop eating and slowly deteriorate. By the time the eggs hatch, she will be dead. For this reason the lifespan among octopuses is very short, the biggest species can live up to 4-5 years, while some species have a lifespan of only 6 months. Even here the LPSO has proven to be completely unique. In captivity, females have been seen to live up to 2 years, and during the whole time the females would continuously mate, lay eggs and brood over and over again.

Because both male and female octopuses usually die before their eggs hatch, it is not possible for them to pass down knowledge to their young, but perhaps the LPSO have opened the door for even faster evolution of octopus intelligence? They do seem to be pretty smart, as they have developed a pretty clever way of hunting shrimp:

Sneaky hunters

While other octopuses rely on speed and surprise, jumping on their prey with one fast pounce, the LPSO has a more elegant approach when it comes to hunting shrimp. It stalks it’s prey by laying low and slowly creeping closer. When it is close enough it carefully extends one of it’s arms around to the other side of the shrimp, then taps it gently on the shoulder. The shrimp totally falls for this prank and instinctively runs in the direction that they think is away from the danger, ending up jumping straight into the beak of the waiting octopus.

It is not known whether this behaviour has developed as a genetic instinct among the octopuses, or if this is a skill that they learn from each other. Maybe this is proof that the social interaction has it’s benefits?

The first one to describe the bizarre behaviour of this octopus was Arcadio Rodaniche, a biologist from Panama. The LPSO can only be found in the murky waters outside Nicaragua, and are very difficult to study in the wild. However, the report Rodaniche submitted after studying some samples of the LPSO in a salt water pool were dismissed, since it suggested a behaviour completely unlike any other known octopus or cephalopod. It was not until in 2012 that a couple of biologists from the University in Chicago, Roy Caldwell and Richard Ross, got hold of some new samples and could confirm the results. In 2015 the two biologists, together with Rodaniche and Christine Hubbard, published an updated study of this unusual octopus. The original publication can be found online here:

Even if this octopus seems special, it also possible that we just don’t know so much about octopuses as we think. Octopuses are hard to study in the wild, so there might be a lot of behaviours that we are not aware of. It is also possible that the unique qualities of the LPSO is part of an evolutionary trend. You never know, maybe we are watching the first cephalopod neanderthals taking their first steps towards building cities under the sea in a couple of thousand years?

I hope you have enjoyed this first animal fact post on this blog. Stay tuned for the next post: animals who use makeup!

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