Editing Bobtail squid (section)

== Light organ ==
[[File:Bobtail squid light organ silhouette.svg|thumb|alt=Diagram showing how the light organ in a bobtail squid emits light downwards to obscure its silhouette|Light from the light organ of a bobtail squid obscures its silhouette]]

Bobtail squid have a [[symbiotic]] relationship with [[bioluminescent]] [[bacteria]] (''[[Aliivibrio fischeri]]''), which inhabit a special light organ in the squid's mantle. The luminescent properties of the bacteria regulate gene expression in the light organ.<ref>{{Cite journal|last=Peyer|first=Suzanne M.|last2=Pankey|first2=M. Sabrina|last3=Oakley|first3=Todd H.|last4=McFall-Ngai|first4=Margaret J.|date=February 2014|title=Eye-specification genes in the bacterial light organ of the bobtail squid Euprymna scolopes, and their expression in response to symbiont cues|journal=Mechanisms of Development|volume=131|pages=111–126|doi=10.1016/j.mod.2013.09.004|issn=0925-4773|pmc=4000693|pmid=24157521}}</ref> The bacteria are fed a sugar and amino acid solution by the squid and in return hide the squid's [[silhouette]] when viewed from below by matching the amount of light hitting the top of the mantle. This method of [[counter-illumination]] is an example of animal [[camouflage]].

The organ contains filters which may alter the [[wavelength]] of luminescence closer to that of downwelling [[moonlight]] and [[star#Radiation|starlight]]; a [[lens (anatomy)|lens]] with [[biochemical]] similarities to the squid's eye to diffuse the bacterial luminescence; and a [[mirror|reflector]] which directs the light [[ventral]]ly.<ref name=McFall-Ngai />