Teuthowenia pellucida, a species of glass squid, is a cosmopolitan southern sub-tropical species, and is abundantly represented in local New Zealand collections. However, due to the depth at which adult specimens live, little is known about its systematics, biology or trophic importance. Morphological similarities between this and other cranchiid genera at early ontogenetic phases make accurate identification of small specimens difficult. Herein, the morphological changes characterising six pre-adult developmental stages (termed A–F) are reported in detail, as well as adult morphology; new information is provided on fecundity. The retinal structure of Teuthowenia’s proportionally large eyes is examined, including photoreceptor length and ommin movement, at various life phases. Finally, a meta-analysis of global predators examines the role of Teuthowenia in both photic and aphotic marine ecosystems. These findings comprise a small contribution toward the knowledge of this little-known genus within the Cranchiidae.