Ensuring the health and welfare of animals in research is paramount, and the normal
functioning of the digestive tract is essential for both. Here we critically assess non- or
minimally-invasive techniques which may be used to assess a cephalopod’s digestive
tract functionality to inform health monitoring. We focus on: (i) predatory response as an
indication of appetitive drive; (ii) body weight assessment and interpretation of deviations
(e.g., digestive gland weight loss is disproportionate to body weight loss in starvation);
(iii) oro-anal transit time requiring novel, standardized techniques to facilitate comparative
studies of species and diets; (iv) defecation frequency and analysis of fecal color (diet
dependent) and composition (parasites, biomarkers, and cytology); (v) digestive tract
endoscopy, but passage of the esophagus through the brain is a technical challenge;
(vi) high resolution ultrasound that offers the possibility of imaging the morphology of the
digestive tract (e.g., food distribution, indigestible residues, obstruction) and recording
contractile activity; (vii) needle biopsy (with ultrasound guidance) as a technique for
investigating digestive gland biochemistry and pathology without the death of the animal.
These techniques will inform the development of physiologically based assessments of
health and the impact of experimental procedures. Although intended for use in the
laboratory they are equally applicable to cephalopods in public display and aquaculture.En prens