Spiral valve
part of a shark intestine
A spiral valve or scroll valve is the corkscrew-shaped lower portion of the intestine of some sharks, Acipenseriformes (sturgeon and paddlefish), rays, skates, bichirs, Lepisosteiformes (gars), and lungfishes. A modification of the ileum, the spiral valve is internally twisted or coiled to increase the surface area of the intestine which increases nutrient absorption.
Description
The intestines of a shark are much shorter than those of mammals. Sharks have compensated for this problem by having a spiral valve, or a scroll valve, inside the intestine to increase the absorbent surface of the intestine. By keeping digestible material in the ileum for an extended period maximum nutrient absorption is ensured. For this reason, many sharks and related fish feed very infrequently. The food passes into the comparatively short colon of the shark almost fully digested, and then out the cloaca and vent.
A consequence of the spiral valve constricting the lumen of the ileum is that sharks cannot pass large hard objects (such as bones) through their lower intestine. Such objects instead remain in the stomach until sufficiently broken down for passing through the valve region, or are regurgitated. Consequently, shark stomachs often contain items of interest that enable one to determine what the animals feed on, as well as non-food items ingested during a feeding frenzy.
The public source identifies “Spiral valve” as part of a shark intestine. This brief keeps that definition visible, then builds a research path around Spiral, valve and part.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Jul 11, 2026. The linked authority identifier is Q1848899. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Spiral valve” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.