Note: author names have not been changed to protect the innocent
Abstract Teuthowenia pellucidais a cosmopolitan southern sub-tropical species, and is abundantly represented in local New Zealand collections. However, because of the morphological similarities between this and other cranchiid genera at early ontogenetic stages, accurate identification of small specimens can be difficult. Herein, the morphological changes characterizing six pre-adult developmental stages (termed A–F) are reported in detail, as well as adult morphology; new information is provided on fecundity. These findings comprise a small contribution toward eventual resolution of the systematically unstable Cranchiidae.
Yeah, Teuthowenia (and many of the cranchiids) tend to make it into deep sea books. They seem quite photogenic. "Glass squid" is actually a common name given to the whole family, as many of them are do the behavior you mention.
The cranchiid Teuthowenia pellucida, like many deep-sea squid species, possesses large eyes that maximise light sensitivity in a nearly aphotic environment. To assess ontogenetic changes in the visual system, we conducted morphometric and histological analyses of the eyes using specimens from New Zealand collections. While the ratio between eye diameter and mantle length maintained a linear relationship throughout development, histological sections of the retina revealed that the outer photoreceptor layer became proportionally longer as the animal aged, coincident with a habitat shift into deeper, darker ocean strata. Other retinal layers maintained the same absolute thickness as was observed in paralarvae. Granules of the pigment ommin, normally located in the screening layer positioned at the base of the photoreceptors, were also observed at the outer end of the photoreceptor segments throughout the retina in young and mid-sized specimens. Early developmental stages of this species, dwelling in shallow waters, may therefore rely on migratory ommin to help shield photoreceptors from excess light and prevent over-stimulation. The oldest, deeper-dwelling specimens of T. pellucida examined had longer photoreceptors, and little or no migrated ommin was observed; we suggest therefore that short-term adaptive mechanisms for bright light conditions may be used primarily during epipelagic, early life stages in this species.