Larsen John H, Guthrie Dan J
Department of Zoology, Washington State University, Pullman, Washington 99163 and Department of Biology, Gonzaga University, Spokane, Washington 99202.
J Morphol. 1975 Oct;147(2):137-153. doi: 10.1002/jmor.1051470203.
High speed cinematography was used to record the feeding activities of terrestrial Ambystoma tigrinum melanostictum. A description of these activities based on films of more than 50 feeding sequences is presented, and the mechanical units involved are defined, described, and functionally analyzed. Evolutionary implications of the feeding system are discussed. In a typical feeding sequence, A. t. melanostictum stations and maintains its lower jaw 3-5 mm from the prey. The mouth is then opened to form a gape of ∼60° by raising the anterior end of the flexed skull and by elevating and advancing the trunk while the mental symphysis of the lower jaw remains stationary. As the mouth opens the bulging tongue is recontoured so that the posterior glandular region becomes the tip of the fully protruded tongue, which may extend 3 to 7 mm beyond the symphysis. Dorsally the protruded tongue has a deep central depression and pronounced anterolateral rims. The anterior rim collapses on contact, thereby engulfing the prey in a sticky trough that retains it during tongue withdrawal. The cervical region is then flexed and the skull snaps downward. If the prey resists the tongue and is captured by marginal teeth, A. t. melanostictum relies on repeated tongue protraction and retraction, in some cases accompanied by inertial feeding. Swallowing involves gular expansion and contraction, and is accompanied by eye depression. When the mouth is opened during ingestive activities, the lower jaw remains in place. Apparently, A. t. melanostictum uses the dorsal trunk, the cucullaris major and the robust heads of the depressor mandibulae muscles to open the mouth. During skull elevation the lower jaw is partially immobilized by the geniohyoideus, and rectus cervicis superficialis muscles. The subarcualis rectus I muscles are prime movers in tongue projection. Hebosteoypsiloideus muscles assist in tongue protrusion by slackening the rectus cervicis profundus muscles that would otherwise restrict anterior displacement of the otoglossal cartilage and copula. Tongue contouring is performed by the complex genioglossus musculature. Sublingual and anterolingual sinuses facilitate protrusion and contouring by providing space and lubrication. Rectus cervicis muscles (profundus and superficialis) are responsible for tongue withdrawal. Closure of the mouth is accomplished by the four levator mandibulae muscles, and again the lower jaw is immobilized, mostly by ventral longitudinal muscles. Skull-trunk elevation during prey capture and ingestion was also observed and filmed in several other species of Ambystoma, in Dicamptodon ensatus, and in two salamandrid species. Apparently raising and straightening the craniovertebral axis, while the mental symphysis retains contact with the substratum, is a common feature of urodele feeding systems, and does not require peculiar morphological adaptations.
利用高速摄影技术记录了虎纹钝口螈黑化亚种（Ambystoma tigrinum melanostictum）在陆地上的捕食活动。本文基于50多个捕食序列的影片对这些活动进行了描述，对其中涉及的机械单元进行了定义、描述和功能分析。讨论了该捕食系统的进化意义。在典型的捕食序列中，虎纹钝口螈黑化亚种会停在猎物前方，使其下颌离猎物3 - 5毫米。然后张开嘴巴，通过抬起弯曲头骨的前端、抬高并向前推进躯干，同时下颌的颏联合保持不动，形成约60°的张口。随着嘴巴张开，鼓起的舌头重新塑形，使后部的腺体区域成为完全伸出的舌头的尖端，该尖端可能伸出颏联合3至7毫米。从背面看，伸出的舌头有一个深深的中央凹陷和明显的前外侧边缘。前边缘在接触时塌陷，从而将猎物卷入一个粘性凹槽中，在舌头缩回时将其保留。然后颈部弯曲，头骨向下猛咬。如果猎物抵抗舌头并被边缘牙齿捕获，虎纹钝口螈黑化亚种会依靠反复伸出和缩回舌头，在某些情况下还会伴随着惯性捕食。吞咽包括喉部的扩张和收缩，并伴有眼球下陷。在摄食活动中嘴巴张开时，下颌保持在原位。显然，虎纹钝口螈黑化亚种利用背躯干、大颈阔肌和强大的下颌降肌头部来张开嘴巴。在头骨抬起过程中，下颌被颏舌骨肌和颈浅直肌部分固定。弧下直肌I是舌头伸出的主要推动者。颈深直肌会限制耳舌软骨和联合突的向前位移，而颈骨肌通过放松该肌肉来协助舌头伸出。复杂的颏舌肌负责舌头塑形。舌下和舌前窦通过提供空间和润滑来促进舌头伸出和塑形。颈直肌（深肌和浅肌）负责舌头缩回。嘴巴的闭合由四块下颌提肌完成，下颌再次被固定，主要是被腹侧纵肌固定。在其他几种钝口螈属物种、太平洋巨螈（Dicamptodon ensatus）以及两种蝾螈科物种中，也观察并拍摄到了捕食和摄食过程中头骨 - 躯干的抬起。显然，在颏联合与基质保持接触的同时，抬起并伸直颅椎轴是有尾目动物捕食系统的一个共同特征，并不需要特殊的形态适应。
