Seehafer Kia, Brophy Samantha, Tom Sara R, Crook Robyn J
Department of Biology, Sacramento State University, Sacramento, CA, United States.
Department of Biology, San Francisco State University, San Francisco, CA, United States.
Front Physiol. 2018 Mar 29;9:299. doi: 10.3389/fphys.2018.00299. eCollection 2018.
Cephalopod molluscs are known for their extensive behavioral repertoire and their impressive learning abilities. Their primary defensive behaviors, such as camouflage, have received detailed study, but knowledge is limited to intensive study of relatively few species. A considerable challenge facing cephalopod research is the need to establish new models that can be captive bred, are tractable for range of different experimental procedures, and that will address broad questions in biological research. The Hawaiian Bobtail Squid () is a small, tropical cephalopod that has a long history of research in the field of microbial symbiosis, but offers great promise as a novel behavioral and neurobiological model. It can be bred in the laboratory through multiple generations, one of the few species of cephalopod that can meet this requirement (which is incorporated in regulations such as EU directive 2010/63/EU). Additionally, laboratory culture makes an ideal model for studying ontogeny- and experience-dependent behaviors. In this study, we show that captive bred juvenile and adult produce robust, repeatable defensive behaviors when placed in an exposed environment and presented with a visual threat. Further, adult and juvenile squid employ different innate defensive behaviors when presented with a size-matched model predator. When a 10-min training procedure was repeated over three consecutive days, defensive behaviors habituated in juvenile squid for at least 5 days after training, but memory did not appear to persist for 14 days. In contrast, adult squid did not show any evidence of long-term habituation memory. Thus we conclude that this species produces a range of quantifiable, modifiable behaviors even in a laboratory environment where ecologically-relevant, complex behavioral sequences may not reliably occur. We suggest that the lack of long-term memory in adult squid may be related to their less escalated initial response to the mimic, and thus indicates less motivation to retain memory and not necessary inability to form memory. This is the first demonstration of age-related differences in defensive behaviors in , and the first record of habituation in this experimentally tractable genus of squid.
头足类软体动物以其广泛的行为模式和令人印象深刻的学习能力而闻名。它们的主要防御行为，如伪装，已经得到了详细研究，但相关知识仅限于对相对较少物种的深入研究。头足类研究面临的一个重大挑战是需要建立新的模型，这些模型能够在圈养条件下繁殖，适用于一系列不同的实验程序，并能解决生物学研究中的广泛问题。夏威夷短尾乌贼（）是一种小型热带头足类动物，在微生物共生领域有着悠久的研究历史，但作为一种新型的行为和神经生物学模型具有很大潜力。它可以在实验室中多代繁殖，是少数能满足这一要求的头足类物种之一（这一要求包含在欧盟指令2010/63/EU等法规中）。此外，实验室养殖使其成为研究个体发育和经验依赖性行为的理想模型。在本研究中，我们表明，圈养繁殖的幼年和成年短尾乌贼在暴露于环境中并面临视觉威胁时，会产生强烈、可重复的防御行为。此外，成年和幼年乌贼在面对大小匹配的模型捕食者时会采用不同的先天防御行为。当连续三天重复进行10分钟的训练程序时，幼年乌贼的防御行为在训练后至少5天内出现习惯化，但记忆似乎不会持续14天。相比之下，成年乌贼没有表现出任何长期习惯化记忆的证据。因此，我们得出结论，即使在一个生态相关的复杂行为序列可能无法可靠发生的实验室环境中，该物种也会产生一系列可量化、可改变的行为。我们认为，成年乌贼缺乏长期记忆可能与其对模拟物的初始反应不那么激烈有关，因此表明其保留记忆的动机较小，而不是必然无法形成记忆。这是首次证明短尾乌贼防御行为存在年龄相关差异，也是首次记录这种在实验上易于处理的乌贼属中的习惯化现象。
