Diet and Feeding Chronology of Diaphus taaningi (Myctophidae) in the Cariaco Trench

• Published in: Copeia 1975-05, Vol.1975 (2), p.356-365
• Main Authors: Baird, Ronald C., Hopkins, Thomas L., Wilson, Donald F.
• Format: Article
• Language: English
• Subjects: Biomass; Diaphus taaningi; Diet; Fish feeding; Gastrointestinal secretions; Intestines; Larvae; Marine; Marine ecology; Marine fishes; Plankton; Stomach
• ISSN: 0045-8511; 1938-5110
• DOI: 10.2307/1442891

Diaphus taaningi, an abundant myctophid resident in the Cariaco Trench, Venezuela, undergoes a pronounced diurnal vertical migration between a daytime depth of 250 m and the upper 50 m at night. Gut analyses indicate that D. taaningi feed primarily on herbivorous zooplankton; copepods and larvaceans constitute better than 70% of the total prey biomass and 97% of the total prey number. Prey items were small compared to fish length, with most items being less than 4 mm long. Certain morphological attributes of D. taaningi are discussed in conjunction with diet. Fish taken between evening ascent and midnight contained many prey items, while those taken prior to evening ascent were essentially empty. It appears that most of the feeding occurs early in the evening, with the remainder of the night being spent in digestion. Estimates of feeding rate and minimum prey density required to obtain the observed ration were 1.14 items/min and 154 items/ m3, respectively. Several predictions concerning trophic organization in the Cariaco Trench are presented, together with a discussion of some ecological implications of the data.