There are two ctenidia oriented so that the inhalent streams pass over each, then converge and exit as a single exhalent stream. Examine a piece of a ctenidium under the dissecting scope. Prepare a wet-mount slide with a smaller piece and view it with the compound microscope. The paired excretory organs of the molluscs are closely associated with the heart. Inorganic substances may be taken back into the blood, and the composition of the excreta is determined by the extent of renal secretion and reabsorption.
Excretory material is passed to the mantle cavity and voided in the excurrent respiratory system.
The cephalopod kidney is derived from two separate renal organs that have fused. The kidney is closely associated with the branchial hearts , which are swellings of the blood vessels at the base of the ctenidia. The contractions of the branchial hearts force fluid through the walls of the blood vessels into the kidney. If necessary, in your opened Loligo , remove the thin skin covering the organs of the visceral mass. Locate the rectum ending in the anus at the base of the siphon.