Prey-Handling Behavior of Three Species of Homalopsine Snakes: Features Associated with Piscivory and Duvernoy's Glands

Abstract

-The homalopsine species, Enhydris plumbea, Cerberus rynchops, and Homalopsis buccata, are aquatic snakes with well developed Duvernoy's glands and grooved posterior maxillary teeth. General features of the feeding behavior of these species were described based on the laboratory observations. Effects of prey size and type on prey-handling behavior and ontogenetic change were investigated using neonate and young snakes. All feeding occurred under water. After seizing prey, snakes remained motionless for periods related to prey size and type. In some cases, snakes anchored the posterior part of the body on submerged stones during handling. Neonate E. plumbea occasionally dropped fish during positioning. In some cases, snakes showed a unique release-and-regrip maneuver for preingestion positioning of prey instead of typical lateral jaw walking maneuver. Ontogenetic change was observed only as the reduction of swallowing duration. Most fish were swallowed head first irrespective of size, whereas direction of ingestion of frogs and tadpoles depended largely on initial bite position. Although some prey animals were killed before swallowing, most were only weakened and swallowed alive. I suggest that characteristics of preyhandling behavior of E. plumbea, C. rynchops, and H. buccata are related to their aquatic and piscivorous habits. Particularly, obligatory head first ingestion of fish seems to be an adaptation for piscivory. I also suggest that the primary biological role of Duvernoys secretions of these snakes is to incapacitate prey animals to aid prey-handling. . , . , . -50, 1998 i ia s a d eptiles