Ommastrephid squid produce some of the smallest cephalopod hatchlings, whose feeding behavior has not been observed. The present study aimed at indirectly filling this knowledge gap by describing ontogenetic changes in beak morphology and morphometry and integrating these results with published datasets on Illex argentinus arm crown morphology and gut contents. Individuals [0.7–15 mm mantle length (ML)] were measured, weighed, and had their buccal mass extracted. Jaw measurements were correlated with ML to determine whether jaw development occurred linearly with ML. For a 10 mm increment in ML, weight increased 430-fold. The jaws of hatchlings were rudimentary, but in larger paralarvae the rostrum protrudes and the jaw features (teeth, slit, groove) disappear. Increases in ML were predicted by beak robustness indices and rostrum protrusion, with growth discontinuities pointing to faster growth in individuals ≤ 2 mm ML. Morphological changes in the beak and arm crown are in synchrony with a transitional event in the feeding ecology of paralarvae: the onset of active predation on crustaceans and masticating their exoskeletons for ingestion. Integration of the results with published data has led to the proposal of a hypothesis of four size-differentiated developmental stages in the feeding ecology of I. argentinus rhynchoteuthions.

中文翻译：

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绑手：喙发育与雌性乌贼副幼虫摄食相关形态变化的同步性

Ommastrephid 鱿鱼生产一些最小的头足类幼体，其进食行为尚未观察到。本研究旨在通过描述喙形态学和形态测量学的个体发生变化，并将这些结果与已发表的关于阿根廷冬青树臂冠形态和肠道内容物的数据集相结合，间接填补这一知识空白。对个体 [0.7-15 毫米地幔长度 (ML)] 进行测量、称重并提取其颊部质量。下颌测量与 ML 相关，以确定下颌发育是否与 ML 呈线性关系。ML 增加 10 毫米，重量增加 430 倍。幼龟的颌骨发育不全，但在较大的副幼虫中，喙部突出，颌骨特征（牙齿、狭缝、凹槽）消失。ML 的增加是通过喙鲁棒性指数和讲台突出来预测的，生长不连续性表明个体≤ 2 mm ML 生长更快。喙和臂冠的形态变化与副幼虫摄食生态的过渡事件同步：开始对甲壳类动物进行主动捕食并咀嚼它们的外骨骼以供摄取。将结果与已发表的数据相结合，提出了在 I. argentinus rhynchoteuthions 的饲养生态学中四个大小分化发育阶段的假设。