Gastric evacuation of the lemon shark Negaprion brevirostris (Poey) under controlled conditions.
Gastric evacuation of the juvenile lemon shark, Negaprion brevirostris, a tropical inshore apex predator, was studied in the laboratory under conditions of 25 degrees C and 32% salinity. Sharks were starved for 48-96 h after which they were fed a 2.7% body weight meal of fish fillet. Gastric evacuation was assessed by stomach lavage every 3 h for 24 h thereafter. Results showed that the gut is emptied in about 24 h with fillets being removed from the stomach following the equation Y = Yoe-bt, where Y is percent of meal recovered at time t, Yo is the initial meal size, and b is the instantaneous rate of evacuation. The exponential function of gastric evacuation in the lemon shark is similar to that in teleosts, but the kinetics are slower. The caloric density of the meal remaining in the stomach increased, approaching that of protein in the first 12 h after feeding, as carbohydrates (glycogen) were digested. After 12 h the caloric value dropped as protein was digested, suggesting an orderly and efficient intake of food energy by the lemon shark.
Schurdak
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Divison of Biology and Living Resources, Rosensteil School of Marine and Atmospheric Science, University of Miami, FL 33149.
Gruber
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D000818:Animals; D002151:Calorimetry; D004032:Diet; D004040:Dietary Carbohydrates / Q000378:metabolism; D004044:Dietary Proteins / Q000378:metabolism; D005260:Female; D005746:Gastric Emptying; D005751:Gastric Lavage; D008297:Male; D008954:Models, Biological; D012737:Sex Factors; D012754:Sharks / Q000378:metabolism*; D013997:Time Factors
D004040:Dietary Carbohydrates; D004044:Dietary Proteins