Transcription of audio taken from a video recorded by Aurelie McTier, 20^th June 2022. The main speaker in the video is an unknown tour guide/boat driver.

[Sound of a boat, waves and people chattering. The engine dies down as does the chatter.]

If I can get your attention, please, I think we are in a good spot now. I might be wrong – it happens every so often, less than it used to – but I think there is a very interesting animal on that rock there. Can anyone see it?

[Man’s voice: That rock there?]

Yep, that rock just there. If you can’t see it that’s alright. This animal is very good at hiding itself. Camouflaging. I’ve got some snacks in this box here, maybe we can get it to reveal itself.

[Sounds of a metal box opening.]

[Woman’s voice: Oh my god it’s a fish.]

It is a fish. Not this animal’s favourite food but one that’s easier for me to get. Watch closely and if we’re lucky it will take the bait. [Mumbling] This is going to be really embarrassing if it’s just a rock again.

Alright, one…two…three…

[Screams and shouts. Lots of talking over each other. Snippets can be made out: “What was that, a snake?”; “Almost gave me a heart attack.”; “Oh my god tentacles!”; “Yes! I was right first time!”]

What we just saw was a basking octopus. They’re found all over the islands, but do especially well on the reef where there are lots of rocks and ledges either just below or just sticking out of the water. These octopuses haul themselves onto a rock and then…wait. They can sit on rocks for hours without going back into the water and they do this for three reasons.

Firstly, they store a large volume of water inside their body cavity and use a specialised series of muscles to keep it circulating over their gills drawing out as much oxygen as possible. Secondly, the chemical that carries oxygen in the blood - haemocyanin – is way more efficient than in other octopuses. Thirdly, as their name says they bask. By lying spread out on the rocks and being so dark in colour, they are warmed by the sun meaning they can slow their own metabolism and save energy.

Their dark colour also helps them blend in with the black rocks and like many octopuses they can change the colour and texture of their skin to appear as rock-like as possible. This makes them almost invisible, especially if you’re their favourite food, fast flying seabirds that aren’t paying attention to anything but the water.

Look around at all the colourful birds flying around the reef. They’re marquinhets of different species and the most colourful is the sunset marquinhet. That bird is a skimmer. It flies low and fast over the water’s surface, quickly grabbing fish as it flies by. As it flies it moves up and down over waves and rocks and if it passes over a basking octopus – bam! Those two grabbing tentacles we saw earlier launch up into the air and grab the bird.

Those tentacles are up to two metres long, giving the octopuses good range but even then the birds are fast so the basking octopus has to have quick reflexes. To help spot prey, its eyes are… well they’re not on stalks, but they are raised up slightly, like those of a chameleon. And they’re constantly moving, the only part of them that is while they’re basking. Always looking for their next meal. So slow is their metabolism however, that once they’ve eaten, they don’t need to eat again for over a week.

[Woman: What about the baby ones? Are they not too small to catch birds?]

Good question: yes and no. Yes the baby basking octopuses are far too small to hunt like the adults, but they do still eat birds. When they’re newborn they float around in the sea eating whatever they can find. Once they become juvenile, they move into rockpools on the beaches at either end of the reef. They wait there for wading birds, especially slenderbills, to wander over to feed in the pool and like a tiny sea monster they lunge from the pools, grabbing the birds with all their tentacles and dragging them into the water.

I’ve seen it happen and honestly it is very distressing. Right, anyway, we’ve seen the basking octopus, we’ve seen birds… let’s power the boat up again and see what other critters we can find. I’m feeling lucky, maybe we’ll make friends with a reefbee…