Malacostracan crustaceans display a large diversity of sizes, morphs and life styles. However, only a few representatives of decapod taxa have served as models for analyzing crustacean olfaction, such as crayfish and spiny lobsters. Crustaceans bear multiple parallel chemosensory pathways represented by different populations of unimodal chemosensory and bimodal chemo- and mechanosensory sensilla on the mouthparts, the walking limbs and primarily on their two pairs of antennae. Here, we focus on the olfactory pathway associated with the unimodal chemosensory sensilla on the first antennal pair, the aesthetascs. We explore the diverse arrangement of these sensilla across malacostracan taxa and point out evolutionary transformations which occurred in the central olfactory pathway. We discuss the evolution of chemoreceptor proteins, comparative aspects of active chemoreception and the temporal resolution of crustacean olfactory system. Viewing the evolution of crustacean brains in light of energetic constraints can help us understand their functional morphology and suggests that in various crustacean lineages, the brains were simplified convergently because of metabolic limitations. Comparing the wiring of afferents, interneurons and output neurons within the olfactory glomeruli suggests a deep homology of insect and crustacean olfactory systems. However, both taxa followed distinct lineages during the evolutionary elaboration of their olfactory systems. A comparison with insects suggests their olfactory systems ö especially that of the vinegar fly ö to be superb examples for “economy of design”. Such a comparison also inspires new thoughts about olfactory coding and the functioning of malacostracan olfactory systems in general.

Malacostracan甲壳类动物显示出各种各样的大小，形态和生活方式。但是，只有十足动物分类群的少数代表用作分析甲壳类嗅觉的模型，例如小龙虾和多刺龙虾。甲壳类动物在口器，四肢和主要在其两对触角上具有多个平行的化学感觉通路，这些通路由不同群体的单峰化学感觉和双峰化学和机械感觉传感器代表。在这里，我们专注于与第一对触角即麻醉剂上的单峰化学感觉传感器相关的嗅觉途径。我们探索了这些感觉器在整个疟原虫分类群中的不同排列，并指出了在中央嗅觉途径中发生的进化转化。我们讨论化学感受器蛋白的进化，主动化学感受的比较方面和甲壳类嗅觉系统的时间分辨。根据高能限制条件查看甲壳动物大脑的进化可以帮助我们了解其功能形态，并建议在各种甲壳动物谱系中，由于代谢限制，它们的大脑会聚在一起。比较嗅觉肾小球内传入，中间神经元和输出神经元的连线，表明昆虫和甲壳类嗅觉系统具有很深的同源性。但是，两个类群在嗅觉系统的进化过程中遵循不同的世系。与昆虫的比较表明它们的嗅觉系统（尤其是醋蝇的嗅觉系统）是“设计经济”的绝好例子。