Do cephalopods use background matching or colour disruptive camouflage?
Cephalopods are
part of the mollusc class which includes octopi, squid, nautilus and
cuttlefish (Hanlon et al., 2009). In this blog post I will be discussing cuttlefish,
octopi and squid, as they are the masters of camouflage. Please note, to make this article read fluidly I will group them as cephalopods, but be mindful I am not referring to nautilus.
Pictures of the same cuttlefish seconds apart |
For this blog I
wanted to find out if cephalopods use background matching or colour disruptive
camouflage. As you may remember I discussed background matching a few weeks ago. If you don’t
remember or can’t be bothered going back and reading, I’ll just tell you that
background matching is when the organism’s colouring matches its background (Caro, 2005). Disruptive colouration (which I
also discussed a
couple of weeks ago) is the use of contrasting markings of an organism to break
up the body edge and to confuse prey or predator (Skelhorn & Rowe, 2016).
To answer the
question of what type of camouflage cephalopods use, I must delve into how they do it first. I will do my best
to explain this but even after reading many research papers I am still trying
to get my head around it. Perhaps it is not as complex as I make out but just
purely mind-blowing!
Cephalopods have
these organs in their upper most dermis (skin) called chromatophores (Williams
et al., 2019). Chromatophores are tiny sacs that contain pigment and are
contracted or relaxed by radial muscles (Hanlon, 2009). They can change shape and size extremely quickly allowing cephalopods to seemingly appear and
disappear within seconds (Allen et al., 2009). Cephalopods also have light
reflective cells which can reflect almost any colour and can even appear to be
fluorescent (Williams et al., 2019).
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Octopus chromatophores in skin |
Cephalopods use
papillae to change the texture of their skin (Allen et al., 2009). There is
much to be learnt about the papillae, but they are believed to use muscular
hydrostatic mechanisms (Allen et al., 2009). The movement of the papillae can
make the skin go from smooth to spikey in just over two seconds (Hanlon, 2007).
This helps cephalopods mimic textures of seaweed, rocks, sand and so much more
in the sea.
Now, to go back
to our question - do cephalopods use background matching or colour disruptive
camouflage? They use both! Cephalopods change their colouration to whatever the
situation asks for and can do it in a matter of seconds (Hanlon, 2009). I am
going to leave you with a few clips about cephalopods using their colourations
as predators and prey. I truly believe that cephalopods are the kings and queens of camouflage.
References
Allen J.,
Mathger L., Barbosa A., & Hanlon R. (2009). Cuttlefish Use Visual Cues to
Control Three-Dimenional Skin Papillae for Camouflage. Journal of Comparative Physiology. 195(6), 547-555.
Caro T. (2005)
The Adaptive Significance of Coloration in Mammals. BioScience. 55(2), 125-136).
Hanlon R.
(2007). Cephalopod Dynamic Camouflage. Current
Biology. 17(11), R400-R404.
Hanlon R., Chiao
C., Mathger L., Barbosa A., Buresch K., & Chubb C. (2009). Cephalopod
dynamic Camouflage: Bridging the Continuum Between Background Matching and
Disruptive Coloration. Philosophical
Transactions of the Royal Society B. 364, 429-437.
Skelhorn J.,
& Rowe C. (2016). Cognition and the Evolution of Camouflage. Proceedings
of the Royal Society of London. 283(1825), 20152890.
Williams T., Senft S., Yeo J., Martin-Martinez F.,
Kuzirian A., Martin C., BiBona C., Chen C., Dinneen S., Nguyen H., Gomes C.,
Rosenthal J., MacManes M., Chu F., Buehler M., Hanlon R., & Deravi L.
(2019). Dynamic Pigmentary and Structural Coloration Within Cephalopod
Chromatophore Organs. Nature
Communications. 10, 1-15.
Cephalopods are pretty amazing animals! So, my question this week – how can they use disruptive colouration and background matching when they, themselves, are colour-blind?
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