Antipodean scientists have reported that our friends from superorder Selachimorpha (Linnean reference – check!) are probably colour-blind. Certainly most of the sharks I’ve seen (on wildlife documentaries, rather than swimming up the River Cam) do seem to utilise a somewhat monochrome livery.
I did wonder if knowledge that our cartilaginous friends would fail an Ishihara test could be of any assistance in case of an attack. I suppose I could initiate a discussion about snooker – a game poorly suited to the colour-blind – and hope to bore my assailant into submission. However, this would pre-suppose quite a slow attack, access to a hydrophone and some knowledge of snooker on my part – so probably only good in a somewhat limited number of cases.
On the plus side, sharks would enjoy a cheap TV licence – though there is limited shark-centric programming on Freeview (but given the plethora of channels, I’m sure Sky could offer something).
I also wonder how shark opticians would work. Mine (by which I mean, my human optician, I rarely fear being eaten during an ophthalmic examination) tends to keep asking whether the green or red circles are clearer (and now… and now… and now) – but this will be no help for a shark. Perhaps this explains why I have never seen a shark in glasses (the lack of external ears may also be an issue). Either that or they wear contacts – and, let’s face it, they certainly aren’t short of a supply of saline solution!