Fig. 1. Schematic representation of the digestive tract, including the midgut, of Cancer crabs. The digestive tract of the investigated Cancer species can be divided into three distinct regions: the foregut [comprised of the oesophagous (OE), the cardiac sac (CS), the gastric mill (GM) and the pylorus (PY)], the midgut (colored) and the hindgut. The midgut region is comprised of midgut proper, the highly branched hepatopancreas (not included in this schematic) and three associated caeca: the paired anterior midgut caeca (AMC), which arise laterally, one on either side of the midgut just posterior to the pylorus, and the single posterior midgut caecum (PMC), which arises dorsally, at or just anterior to the midgut/hindgut transition (MHT). Regions of the midgut where SIFamide-like immunoreactivity has been localized are shown in green; those in which tachykinin-like labeling was seen are colored red.