I’ve been off for a week with bronchitis, curled up at home coughing violently and generally feeling sorry for myself, so apologies for the posting hiatus. Normal service will now be resumed, and with one of my favourite topics – the octopus.
Octopods come in a wide and wild variety of shapes, colours, and abilities. In a recent post (cephalopod magic), I included a couple of links to short videos of octopods showing off their amazing camouflage skills. The Antarctic octopus can modify its own RNA to allow their nervous system to perform in the incredibly cold environment. There’s an octopus that walks on the ocean floor, and another that hunts for food in inter-tidal pools on the beach, dragging itself from pool to pool in a quest for shellfish and other tasty prey (same post). They’re even quite smart, as can be seen from video in the above posts.
So I’d like to introduce you to two more in the family: the blanket octopus and the glass octopus, both of which inhabit the pelagic zone (a fancy way of saying they spend their time in the upper layers of the water).
First up, the glass octopus – as you might guess, it’s transparent. Almost completely. The only non-transparent parts are the eyes and the digestive gland, so the creature orients itself so that this digestive gland is vertical in the water, casting as small a shadow as possible. This prevents the multitude of hungry predators in the layers below from spotting it as a potential dinner course.
Then there’s the blanket octopus. ‘Blanket’ sounds a little pedestrian, and if I’d had the naming of it, it would probably be the Superhero Cape octopus, or the Pulling The Tentacles Off The Portugese Man ‘O War And Using Them As A Flail octopus, although I grant that the second name might be a little long.
This glorious creature is extremely sexually dimorphic: in this case that means that the female can grow to more than 2 metres, while the males reach at most a few centimetres. And most of the magic is done by the female: two pairs of her tentacles are connected by a fine webbing that’s kept furled up most of the time. When the creature feels threatened, however, she unfurls this webbing, making her look much bigger to potential predators – she can even shed bits to act as a decoy.
Both sexes also have another trick – not only are they invulnerable to the toxins of the Portugese Man ‘O War, but they can also rip tentacles off the deadly creatures and use them as a flail on other ocean denizens. That’s rather like adding insult to injury, but in reverse.
If you can tolerate some rather cheesy piano music and you’d like to see the blanket octopus trailing her elegant superhero cape through sparkling water, here is a nice clear video. Enjoy!
[Feature image: Blanket octopus. Image by Steve Hamedl]