Chitons have a distinctive armature of eight articulating dorsal shells. In all living species, the shell valves are covered by a dense array of sensory pores called aesthetes; but in some taxa, a subset of these are elaborated into lensed eyes, which are capable of spatial vision. We collected a complete ontogenetic series of the eyed chiton Tonicia lebruni de Rochebrune, 1884 to examine the growth of this visual network and found that it expands continuously as eyes are added at the margin during shell growth. Our dataset ranged from a 2.58-mm juvenile with only 16 eyes to adults of 25–31 mm with up to 557 eyes each. This allowed us to investigate the organization (and potential constraints therein) of these sensory structures and their development. Chiton eyes are constrained to a narrowly defined region of the shell, and data from T. lebruni indicate that they are arranged roughly bilaterally symmetrically. We found deviations from symmetry of up to 10%, similar to irregularity reported in some other animals with multiplied eyes. Distances separating successive eyes indicate that, while shell growth slows during the life of an individual chiton, eyes are generated at regular time intervals. Although we could not identify a specific eye-producing tissue or organ, we propose that the generation of new eyes is controlled by a clock-like mechanism with a stable periodicity. The apparent regularity and organization of the chiton visual system are far greater than previously appreciated. This does not imply the integration of shell eyes to form composite images, but symmetry and regular organization could be equally beneficial to a highly duplicated system by ensuring even and comprehensive sampling of the total field of view.

中文翻译：

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眼睛的Chiton Tonicia lebruni中的分布式视觉系统的连续和规则扩展

Chitons具有八个关节背壳的独特衔铁。在所有生物物种中，壳瓣膜被致密的感觉孔阵列（称为麻醉剂）覆盖；但在某些分类单元中，这些分类中的一部分被精制成了有眼睛的双眼，可以进行空间视觉。我们收集了眼睛Chiton Tonicia lebruni的完整的个体发育系列。de Rochebrune，1884年研究了该视觉网络的生长，发现在壳生长过程中，随着在边缘处添加眼睛，该视觉网络不断扩展。我们的数据集范围从2.58毫米的少年（仅16眼）到25-31毫米的成年人（每只最多557眼）。这使我们能够研究这些感官结构及其发展的组织（以及其中的潜在限制）。Chiton的眼睛被限制在壳的狭窄区域，数据来自勒布鲁尼氏菌（T. lebruni）表示它们大致左右对称地排列。我们发现与对称性的偏差高达10％，这与其他一些眼睛多的动物所报告的不规则性相似。分开相继的眼睛的距离表明，尽管壳层在单个Chiton的寿命中增长减慢，但会以固定的时间间隔生成眼睛。尽管我们无法识别出特定的产生眼睛的组织或器官，但我们建议通过具有稳定周期的类似时钟的机制来控制新眼睛的产生。Chiton视觉系统的明显规律性和组织性远远超过了以前的认识。这并不意味着将贝壳眼整合为合成图像，