In representative species of all vertebrate classes, the oral ejection of upper digestive tract contents by vomiting or regurgitation is used to void food contaminated with toxins or containing indigestible material not voidable in the feces.
Vomiting or regurgitation has been reported in a number of invertebrate marine species Exaiptasia diaphana , Cancer productus , and Pleurobranchaea californica , prompting consideration of whether cephalopods have this capability.
We have not identified any publications refuting our hypothesis, so a balanced review is not possible. Overall, the evidence presented is circumstantial, so experiments adapting current methodology e. We recognize the possibility that further research may not support the hypothesis; therefore, we consider how cephalopods may protect themselves against ingestion of toxic food by external chemodetection prior to ingestion and digestive gland detoxification post-ingestion.
Reviewing the evidence for the hypothesis has identified a number of gaps in knowledge of the anatomy e. In the obligative act of eating, animals expose themselves to the ingestion of food potentially contaminated with toxins, which may not have been detected by vision, olfaction, or gustation prior to swallowing Davis et al.
Vomiting in vertebrates describes the forceful ejection of upper digestive tract contents from the body via the mouth in a single coordinated action with the animal usually adopting a characteristic posture assumed to optimize the mechanics of ejection and reduces strain on the body musculature Stern et al. However, regurgitation is used to describe the process by which some mammals and birds Lecomte et al.
