There is very little quantitative experimental information on feeding in chaetognaths and ctenophores because of the difficulty of obtaining undamaged specimens. As important plankton predators, a knowledge of their daily rations as a function of food concentration is vital to ecosystem models of water column trophodynamics. At specified food concentrations, three ctenophore species always ingested higher specific daily rations than three species of chaetognaths. Food consumption of ctenophores increased linearly throughout the food concentration range (exceeding 106 μg C/m3 Although food consumption of chaetognaths reached an upper limit at very high food concentrations, it seemed unlikely that satiation would occur under environmental conditions. Below 10,000 food items/m3 chaetognaths were unable to obtain l% of their specific daily ration, although the few environmental studies based on gut contents suggest substantial feeding even below this concentration. The apparent threshold may reflect the environmental patch density necessary for feeding to begin. At high food concentrations daily rations of newly-hatched ctenophores and chaetognaths can exceed well over 10 times their body carbon. In ctenophores even adults can consume these extremely large rations although chaetognaths follow the more usual pattern, where ration decreases throughout life. Gut residence time of food (where single items were ingested) increased with age and size of food item selected in Sagitta hispida from one to two hours, levelling off after animals reached 6 mm. Mnemiopsis mccradyi maintained a uniform digestion time of one hour as it grew, except for a brief period when it first selected larger-sized food. In older animals of both species, multiple ingestion became more common, where gut residence time was directly proportional to number of food items consumed, ranging up to 5 hours for five or more food items. Chaetognaths showed more variability of gut residence time than did ctenophores. It was concluded that these animals are much better at catching food in the environment than laboratory experiments would suggest.