Cephalopods comprise over 800 species, possess advanced nervous, cardiovascular and visual systems, and are masters of camouflage.  They are also thought to use toxic secretions widely for defence and predation but very little is known about the proteomic composition of these secretions. One such species, Sepiadarium austrinum, the Southern bottletail squid, secretes viscous slime from its underside.  This substance is thought to be toxic to predators such as crabs but the physical structure of slime itself is also of interest because it is remarkably voluminous and rapidly secreted.

Along with identifying the putative toxic proteins within the slime secretions of S. austrinum, this study compares its protein composition to the slime of sea stars and planarians, and speculates on potential similarities in slime mechanism to that of hagfish. Proteins involved in the hagfish slime secretion include calcium regulators as well as intermediate filament proteins, both of which are abundant within S. austrinum slime.

By combining a de novo assembled transcriptome from various tissues including the slime, with the proteomics of S. austrinum slime, our study was able to uncover this remarkable defence mechanism within a relatively unknown species. The method used for identifying proteins in non-model organisms has allowed a greater understanding of the proteins involved in the mechanisms that control the secretion of slime within S. austrinum. This method will also be used on other closely related species to create a comparative proteomic study on the secretions of cephalopods and highlight potentially novel proteins.

Identifying the proteins found within S. austrinum slime is important both from an ecological and evolutionary perspective as well as having the high potential to produce biomedical products, and biomimetics.