Digestive System of Invertebrates

Abstract

Digestion by invertebrates is nominally in two phases: extracellular breakdown of food followed by intracellular digestion; protist invertebrates digest foodstuffs by intracellular means. Invertebrate digestion differs from that of vertebrates in that the former lacks digestive glands opening into the hindgut.

Keywords: invertebrate digestion; symbionts; guts; fluid feeders; microphagous digestion; contact digestion; lysosomal digestion; regulation of digestion; intracellular digestion; extracellular digestion; invertebrate nutrition; symbiosis

Figure 1.

The basic invertebrate gut.

Figure 2.

Secretory cells of the primary ducts of the digestive diverticula of Tridacna gigas. MAS, microapocrine secretion of digestive enzymes.

Figure 3.

Tubule of the digestive diverticula of Tridacna gigas illustrating the digestive cells (top) in various phases of intracellular digestion, and holocrine secretion of excretory spherules. Compound flagella of crypt cells eject excretory spherules from tubule lumen towards the primary ducts, and into stomach. TB, blind‐ended digestive tubule; SD, secondary duct of the digestive diverticula; PD, primary duct of the digestive diverticula.

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Further Reading

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How to Cite close
Fankboner, Peter V(May 2003) Digestive System of Invertebrates. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0003645]