[3][4] The type specimen was collected off the Hawaiian Islands and is located at the National Museum of Natural History in Washington, D.C.[5] Euprymna scolopes grows to 30 mm (1.2 in) in mantle length.

[10][11] Euprymna scolopes lives in a symbiotic relationship with the bioluminescent bacteria Aliivibrio fischeri, which inhabits a special light organ in the squid's mantle.

To allows this symbiotic relationship, Crumbs protein must first induce Apopstosis, which kills superficial epithelial tissue found in Euprymna scolopes.

[23] Besides the relentless host-derived current that forces motility-challenged bacteria out of the pores, a number of reactive oxygen species makes the environment unbearable.

[23] Squid halide peroxidase is the main enzyme responsible for crafting this microbiocidal environment, using hydrogen peroxide as a substrate, but A. fischeri has evolved a brilliant counterattack.

A. fischeri possesses a periplasmic catalase that captures hydrogen peroxide before it can be used by the squid halide peroxidase, thus inhibiting the enzyme indirectly.

[23] Once through these ciliated ducts, A. fischeri cells swim on towards the antechamber, a large epithelial-lined space, and colonize the narrow epithelial crypts.

[24] In fact, experimental procedures have shown that removing the genes responsible for light production in A. fischeri drastically reduces colonization efficiency.

Another, more evolutionarily important reason may be that daily venting ensures selection for A. fischeri that have evolved specificity for a particular host, but can survive outside of the light organ.

[28] Since A. fischeri is transmitted horizontally in E. scolopes, maintaining a stable population of them in the open ocean is essential in supplying future generations of squid with functioning light organs.