Wondering about mimics?

I have been meaning to write a blog about the Mimic octopus (Thaumoctopus mimicus) and Wunderpus (Wunderpus photogenicus) for ages, but inspiration has eluded me until I was revisiting some of my earlier research on charismatic muck dive species. Both the mimic octopus and the wunderpus are very popular with critter enthusiasts, but we know surprisingly little about them. Time to change that or at the very least tell you some of the things we know about them!

Wunderpus

A wunderpus (Wunderpus photogenicus) checks out my camera

If you’re not a diver or you have never heard of them, the Mimic and the Wunderpus are very (very!) funky species of octopus. They have a wide range of interesting behaviour, they look amazing, and both are found on sandy habitats in the tropics. What they also have in common is that both were only recognised as new species fairly recently (2005 and 2006).

Just by reading their scientific names you could imagine these are not your average cephalopod. The wunderpus’ species name “Wunderpus photogenicus” says it all and  is probably also one of the easiest scientific names to remember (except maybe for the brilliantly named “Boops boops“). “Thaumoctopus mimicus” tells you that this particular species is good at mimicry, even for octopus standards.

Best of Dauin_Cephalopod_OctopusMimic

Mimic octopus (Thaumoctopus mimicus) foraging on the sand

Both species live on soft sediment (mostly sand) habitats and they have evolved to be perfectly adapted to this lifestyle. They live in holes in the sand, are small, have longer arms than your average octopus, and their colours are quite drab. There are a few subtle physical and behavioural differences between the two though.

Wunderpus (2)

Wunderpus partially in its hidey-hole

One of the things I noticed is that their hunting strategies vary slightly. Wunderpus have more extensive “webbing” between their arms than mimics and they use this webbing when hunting. Crabs are a favourite prey of wunderpus and they catch them by spreading their mantle (the “web” between their arms) over rocks, holes, or other objects like a big parachute. They then use the tips of their arms to poke the crabs out of their holes, after which they run into the parachute-web and are easily collected with one of the other arms.

Mimic octopus seem to forage more actively and (in my experience) use the parachute-technique less often. Instead they poke their long arms into holes in the sand, scaring out any critter that’s in there and then grabbing it directly. This means that mimics spend even more time moving over the sand than wunderpus do, which might be why they evolved some very particular behaviour.

Mimic

Trying to mimic?

Whenever you search for information about the mimic octopus, one of the first things to come up is that they mimic all kinds of other animals. Unlike other octopuses, it does not just mimic colour, but also the behaviour of up to 6 (or 8 or 12 depending on who you ask). The question is, does a mimic really mimic? Their mimicry is supposed to deter or fool predators or prey, but I wonder if this is really the case, or whether we are over-interpreting things from our human perspective.

Many of the behaviours that have been called mimicry could also be explained by simple logic or physics. Take for instance the idea that they mimic toxic flounders/soles while swimming. Yes, they do look very similar when they swim, but it is also a fast and energy-efficient way to swim over any flat area. Which is undoubtedly why this type of swimming is used by most octopus species living in the sand. Another example is the lionfish-mimic, which could also be explained as a way to look as big as possible when threatened. It’s a very common tactic used throughout the animal kingdom, and if you happen to be an octopus with long arms, you’ll look like a spiky lionfish when spreading them out. Other behaviours can similarly be explained, but I wouldn’t want to bore you with long lists right now.

Does this mean they do not mimic or that I am just a mopey cynical bastard who refuses to be amazed by a fantastic animal? Of course not! I love mimics and they show some  of the most extraordinary behaviour in the ocean. It just means that I want to learn more about them to find out what causes it.

OLYMPUS DIGITAL CAMERA

Close up of a mimic octopus

To study them properly, you first need to be able to tell the wunderpus and mimic octopus apart though! These critters look very similar (stripey), so it’s easy to get confused. Here is what to look for:

  • Arm patterns I: The black/white patterns on the arms of Wunderpus are very sharply defined, compared to more blurry with the mimic. Imagine the patterns on the wunderpus were drawn by a German painter using a pen and ruler, and the ones of the mimic by me with some crayons.
  • Arm patterns II: Mimic octopus have a continuous white outline along the border of each arm. The wunderpus does not have this, instead the band-pattern continues across the border.
  • Head: Mimics have a “U-“-shape on the back of their head, where wunderpus have a white patch.
  • Colour: Wunderpus usually have more of a red/brown colour shade to them than mimics, which are almost always black and white. Careful though, they can both change colour so this is not the best way of telling them apart.
  • Behaviour: The hunting behaviour I described earlier is a hint, though not always consistent. From my experience, wunderpus live in areas where the sand is more coarse (gravelly) than mimic octopus, which could also explain why they have slightly different hunting methods.

Finally, because you made it this far, here is a video I took of mating mimic octopus in Indonesia:

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