Just woke up today and thought about eye differential in Histioteuthis
was a good pondering point.
Here some literature which discusses the importance of it:
Function of the Dimorphic Eyes in the Midwater Squid Histioteuthis dofleini
"The squid Histioteuthis dofleini
, like other members of the family
Histioteuthidae, has a large left eye and a small right eye. The large eye points in a
dorsal posterior direction while the squid typically orients at an oblique angle with
the arms downward. The large eye, as a result, points vertically upward. The small
eye appears to be directed ventrolaterally. This squid occurs primarily at depths of
500 to 700 m during the day where it is exposed to low levels of downwelling light.
Presumably the large eye utilizes this faint downwelling light while the smaller eye
utilizes bioluminescent light" - Young, 1975