Structure and Topographic Distribution of Oral Denticles in Elasmobranch Fishes
Structure and Topographic Distribution of Oral Denticles in Elasmobranch Fishes
复制标题
DOI：
10.1086/bblv222n1p26
复制
发表时间：
2012-02-01
影响因子：
1.6
通讯作者：
Collin, Shaun P.
中科院分区：
文献类型：
--
作者：
Atkinson, Carla J. L.;Collin, Shaun P.
众所周知，软骨鱼外表皮的鳞片或小齿是皮肤上的一层坚硬的保护层，可以减少磨损，也可以作为减少水动力阻力的元素。然而，口腔内小齿的结构和功能尚不确定。这项研究利用体视学和扫描电子显微镜检查了一系列软骨鱼口腔小齿的结构和分布。在所分析的蝙蝠科动物中，只有鼻蝠科的成员具有口腔小齿，而在裸鳐科或蝙蝠科的成员中没有发现小齿。相比之下，除直齿鱼科成员外，所有被检查的鲨鱼都具有口腔细齿。在鲨类中，真鲨科的小齿具有带凹槽的表面和中央棘，该棘向口腔后部倾斜。这些齿状适应有利于减少水动力阻力，这对于这些具有公羊通风的自由游泳物种来说是一个优势。另外，半圆齿科的成员具有宽阔的球状小齿，这些小齿经常重叠，提供坚硬的表面，以保护上皮在食用坚硬的猎物时免受磨损。口腔小齿的分布和大量数量似乎在空间上损害了口腔（味觉）乳头填充口咽腔的能力，但当猎物在口腔内被操纵时，会增加对猎物的摩擦和抓握。
The placoid scales, or denticles, of the external epidermis of elasmobranchs are well known as a hard protective coat over the skin to reduce abrasion or as elements to reduce hydrodynamic drag. However, the structure and function of denticles within the oral cavity is uncertain. Using stereological and scanning electron microscopy, this study examines the structure and distribution of oral denticles in a range of elasmobranchs. Of the batoids analyzed, only members of the Rhinobatidae possessed oral denticles, with no denticles found in the members sampled in the Gymnuridae or Dasyatidae. In contrast, oral denticles were located in all the selachians examined, except for members of the Orectolobidae. Within the selachians, the denticles of the Carcharhinidae have a grooved surface and a central spine, which is angled toward the posterior of the mouth. These denticular adaptations are beneficial to reduce hydrodynamic drag, an advantage for these free-swimming species with ram ventilation. Alternatively, members of the Hemiscyllidae have broad bulbous denticles that often overlap, providing a hard surface to protect the epithelium from abrasion during the consumption of hard-bodied prey. The distribution and high number of oral denticles appears to spatially compromise the capacity for oral (taste) papillae to populate the oropharyngeal cavity but provides increased friction and grip on prey items as they are manipulated within the mouth.