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Gut morphology and function in Atherinops affinis (Teleostei: Atherinopsidae), a stomachless omnivore feeding on macroalgae
Author(s) -
Logothetis E. A.,
Horn M. H.,
Dickson K. A.
Publication year - 2001
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.2001.tb00193.x
Subject(s) - biology , omnivore , digestive enzyme , herbivore , zooplankton , teleostei , ecology , predatory fish , amylase , zoology , fishery , fish <actinopterygii> , enzyme , predation , biochemistry
The marine silverside Atherinops affinis has a short, simple gut and no obvious stomach or physical mechanisms for breaking down algal cells even though its diet in many estuarine habitats is primarily green macroalgae. Silverside from the Upper Newport Bay estuary in southern California had: (1) assimilation efficiencies from a green algal diet of 54% (total organic material), 74% (carbon), 84% (nitrogen), 89% (protein) and 81% (energy), values typical for marine herbivorous fishes; (2) an alkaline gut and no pepsin activity, thus confirming that the fish lacks a stomach; (3) relatively high amylase activity and low trypsin and lipase activities, a digestive enzyme profile expected in a fish consuming a high‐carbohydrate, low‐protein and low‐lipid diet. The fish appears to be capable of functional herbivory and can be classified tentatively as a type III herbivore based on its possible use of pharyngeal jaws for lysis of algal cells.