Digestive and feeding characteristics of the chondrosteans

Synopsis Structure and function of the digestive system and feeding characteristics of the chondrosteans are reviewed. Although the group exhibits a wide diversity of feeding habits including piscivory, benthophagy, and planktivory, they are principally carnivores throughout their life history. Examination of digestive system structure reveals the basic structure to be similar among the species with some modification to accomodate the different food types. For the species studied, composition of the adult digestive enzyme complement is consistent with the carnivorous habits with proteases dominating and only low levels of carbohydrase activity. There are three secretory phases during development of the digestive system. Each corresponds with different food habits of the different life-history intervals. Vision is apparently not utilized for feeding in any interval. Instead food is recognized and located primarily by gustation, olfaction, textural qualities, and, possibly, electroreception.