Vol. 46 No. 5, 2007
When Prey Acts as a Lever: Prey-Handling Behavior of the
Chinese Green Tree Viper, Trimeresurus stejnegeri stejnegeri
Department of Life Science, National Taiwan Normal University, 88 Ting-Chow Rd., Sec. 4, Taipei 116, Taiwan
Tein-Shun Tsai (2007) Snakes
may use tongue flicking and snout touching to locate the head-end of
immobilized prey, but tongue use is limited when snakes are holding
prey after a strike. In this condition, how can they differentiate the
anterior and posterior ends of the prey so that they still ingest their
prey mainly from the anterior end? To answer the question, I analyzed
the prey-handling behavior of Trimeresurus stejnegeri stejnegeri (Viperidae: Crotalinae) in the laboratory. Following the capture of a prey, T. s. stejnegeri
lifted the prey from the ground. The prey thus hung in the air, with
the body tilted, like a lever with the fulcrum at the site of the bite.
In most cases, the snake gradually maneuvered its jaw to the higher end
of the prey and began ingesting it. As an adaptation for arboreal
feeding, the direction of prey ingestion in T. s. stejnegeri
depended largely on the location of the initial bite site, under the
proposed action of gravity. A significantly greater proportion of frogs
(42.1%) were struck in the posterior region than mice (9.6%). The ratio
of prey ingested from the anterior to the posterior ends was 54: 19 for
mice and 24: 14 for frogs.
Key words: Arboreal pit viper, Feeding behavior, Ingestion direction, Gravity.
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