Sleeping Bags For Parrotfish?

By Steve De Neef, December 2, 2010 @ 10:31 AM (EST)

Source: BBC

Ever noticed how sometimes parrotfish can have a cocoon wrapped around them while sleeping? Scientists have recently conducted a study to examine the cocoons function.

The bullethead parrotfish can make a ‘sleeping’ cocoon in about 45 to 60 minutes with mucus secreted from glands near their gills. Dr Alexandra Grutter from the University of Queensland in Australia led the research and exposed reef parrotfish with and without cocoons to skin parasites. Fish inside these sleeping cocoons were attacked less by parasites than the ones without cocoons. Pretty handy for a fish to have these mobile sleeping bags available!

The glands that produce the mucus are very big for the size of the of fish and the researchers believe that the parasites must exert a lot of pressure on parrotfish in order for the fish to have evolved this mechanism.

Comments

Dec 2, 2010 12:15 PM

Dejan Mavric wrote:

Interresting story. This mucuous cocoon is transparent but on a night dive in southern Red sea I found a parrotfish laying on a coral and some sand particles made this cocoon visible on a photo I uploaded in my gallery here. http://www.divephotoguide.com/user/Dejan/gallery/red-sea-2015/
I've benn also told that the cocoon prevents the enemies to smell or otherwise feel the sleeping parrotfish.

Dec 3, 2010 6:33 PM

Wayne Lovell wrote:

I think the parrotfish have another defence mechanism also. I've noticed whenever I approach them they immediately excrete a cloud of sand and swim away quickly. I have a theory that this sand cloud is rather like the octupus' ink cloud and is used as a decoy for predators.

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