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Functional morphology of digestion in the stomachless, piscivorous needlefishes Tylosurus gavialoides and Strongylura leiura ferox (Teleostei: Beloniformes)

journal contribution
posted on 2023-05-18, 04:14 authored by Manjakasy, JM, Ryan DayRyan Day, Kemp, A, Tibbetts, IR
Belonidae are unusual in that they are carnivorous but lack a stomach and have a straight, short gut. To develop a functional morphological model for this unusual system the gut contents and alimentary tract morphology of Tylosurus gavialoides and Strongylura leiura ferox were investigated. The posterior orientation of the majority of the pharyngeal teeth supports the swallowing of whole large prey, but not their mastication. Mucogenic cells are abundant in the mucosa lining, particularly the esophagus, and their secretions are likely to protect the gut lining from damage while lubricating passage of the prey. Esophagus, anterior intestine, posterior intestine, and rectum all have highly reticulate mucosae. The anterior three gut sections are distensible to accommodate the passage of prey. However, following ingestion large prey are passed to the highly distensible posterior intestine where they rest head first against the ileorectal valve. Alimentary pH ranges from neutral to weakly acidic. Fish prey is digested head first with the head being largely digested while the remainder of the body is still intact. The nondistensibility of the rectum and the small aperture provided by the ileorectal valve suggest the products of intestinal digestion are either small particulates or fluids that pass into rectum where they are absorbed.

History

Publication title

Journal of Morphology

Volume

270

Issue

10

Pagination

1155-1165

ISSN

0362-2525

Department/School

Institute for Marine and Antarctic Studies

Publisher

Wiley-Liss

Place of publication

Div John Wiley & Sons Inc, 605 Third Ave, New York, USA, Ny, 10158-0012

Rights statement

Copyright 2000 WILEY-LISS, INC.

Repository Status

  • Restricted

Socio-economic Objectives

Marine biodiversity

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