Day Octopus (Octopus cyanea) Photo by By Ahmed Abdul Rahman – Template:Mwn, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=34663228

Dear Readers, the more I find out about octopuses, the more amazed I am at their intelligence and adaptability. They can also be surprisingly truculent creatures – who can forget the Australian female octopuses who regularly throw silt at male octopuses who are overly amorous? In this week’s New Scientist, there’s an article about Day Octopuses in the Indo-Pacific, who hunt alongside shoals of fish.

The ‘packs’ normally  consist of a single Day Octopus and a small shoal of mixed fish. If a fish makes a direct, urgent movement towards a particular location the octopus will often get involved – its tentacles mean that it can flush small creatures from interstices within rocks or coral, so the fish and the octopus get something to eat. Furthermore, if a fish finds something that it can’t reach and thinks that the octopus hasn’t noticed, it swims backwards and forwards in front of the octopus to get its attention.

But the octopus has no time for freeloaders. The scientist studying the octopus/fish ‘packs’, Eduardo Sampaio, has noticed that the octopus will ‘punch’ fish who are just hanging around rather than helping to find food. Furthermore, of the six species of fish most involved in hunting with the octopus, the Blue Goatfish (Parupeneus cyclostomus) was the most helpful, actively looking for food and signalling when it was found, while the Blacktip Grouper (Epinephelus fasciatus) was something of a slacker, and would just take advantage of the hard work of the octopus and the other fish. Small wonder, then, that the octopuses were only seen to ‘punch’ a Blue Goatfish three times, as compared to walloping the Blacktip Groupers twenty-seven times.

There is a brilliant film of all this happening here – notice how the octopus goes black (usually a sign of annoyance) before punching the fish.

I can think of a few other interactions between different animal species when it comes to food – ravens will signal to wolves and wolverines if there is a carcass that they can’t break into, and the honeyguide (bird) will work with humans and honey badgers if it finds a bees’ nest that it can’t access on its own. I find these examples of cross-species cooperation fascinating, and I’m sure there are many, many more in the sea that no one has documented.

You can read the New Scientist article here, and the whole research paper is here.

Day Octopus (Octopus cyanea) Photo by By Pauline Walsh Jacobson – https://www.inaturalist.org/photos/251606691, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=131674208