[Lionel]

Lionel Marrion  asked the Naked Scientists:
   
Hi there,

My wife recently bought and cleaned a sepia, and the other night i noticed that the discarded cuttlebone was glowing green in the dark. Is this normal?

All the best, 
Lionel.

What do you think?

[imatfaal]

Squid and cuttlefish use bio-luminescence for camoflage and to escape hunters - but its an active process that requires energy from the animal to a symbiot bacteria.  I wonder if the last remaining bio-chemicals reacted to oxygen in the air for one last glow.  Is it still doing it?  Take a picture please!

Some squid use a bioluminescent ink - that puts off predators with s splash of light rather than a cloud of dark ink.  It is possible to imagine how this ink might have contaminated the hard structure of the squid. 

[Bored chemist]

Some bacteria that cause decay also glow. I think that's a more likely reason here.

[Lionel]

Many thanks for your replies.

To add a bit of detail.

The green glow was deep in the cuttle bone and also reached the surface and only affected chunks or strata. By the following day (possibly the third after cleaning) it had reduced significantly. It has now (after a week) completely disappeared.

It was left outside in the shade (probably temps between 12 and 22ºC)

The glow really was quite impressive when strongest, say half as strong as my child's charged up glow in the dark book, but unfortunately i didn't think to try to get a photo.

[Probably a red herring (to keep a watery theme going), but the little ants we have round here (southern spain) were very interested in the cuttlebone and came and grazed on it. I didn't establish if they grazed more or less where the glowing was. Now the bone seems not at all oily and the ants have lost interest, tho it still smells a bit fishy.]   

[Bored chemist]

Rotting fish are noted for their occasional phosphorescence.