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The heat increment of feeding (HIF) is the metabolic response following a feeding period. There is an increase in metabolism following a meal. The heat increment of feeding of the mantis shrimp, Squilla empusa, has not been studied before, although almost half of the published invertebrate HIF studies have been on crustaceans.

The standard metabolic rate is the minimum metabolic rate of a postabsorptive ectotherm, at rest, during its non-active period, at a defined temperature. The standard metabolic rate (SMR) of the mantis shrimp was measured using indirect calorimetry, measuring the dissolved oxygen concentrations of the inflowing water and the outflowing water of a closed system over a 24 hour interval. From there, the oxygen consumption rate (mg/O2/hr/g tissue) was calculated and compared to the time of day to determine the standard metabolic rate of each individual.

A circadian rhythm associated with the SMR was observed where it starts at an average low consumption rate of 0.125 mg/O2/hr/g tissue at around 19:00, reaches an average peak of 0.175 mg/O2/hr/g tissue at about 02:30 and subsequently declines to an average of 0.125 mg/O2/hr/g tissue again until about 09:00. The shrimp consumed the most at night, which is consistent with the fact that they are nocturnal animals. In future studies, the next step would be to measure the oxygen consumption directly following a meal and calculating the difference between the postprandial oxygen consumption and the SMR to determine the HIF.