Chemical signals in the marine environment: dispersal, detection, and temporal signal analysis.

Chemical signals connect most of life's processes, including interorganismal relationships. Detection of chemical signals involves not only recognition of a spectrum of unique compounds or mixtures of compounds but also their spatial and temporal distribution. Both spectral and temporal signal processing determine what is a signal and what is background noise. Each animal extracts its unique information from the chemical world and uniquely contributes to it. Lobsters have provided important information on temporal signal processing. Marine chemical signals can be measured with high spatio-temporal resolution giving us a novel view of the lobster's environment. Lobster chemoreceptor cells have flicker fusion frequencies of 4 Hz and can integrate stimuli over 200 ms, closely corresponding to odor sampling behavior with 4-Hz "sniffs." Using this information, spatial odor gradients can be determined from temporal analysis of odor patches typical of turbulent dispersal. Lobsters appear to use this information to locate odor sources. Lobster social behavior depends greatly on chemical signals. Urine carries important information for courtship, dominance, and individual recognition. A novel gland in the nephropore is strategically located to release its products into the urine. Urine, in turn, is injected into the gill current, which jets water 1-2 m ahead of the animal. Lobsters control three different currents that carry chemical signals to and from them. The study of odor dynamics has only just begun. It will be exciting to see how signal dispersal, receptor temporal tuning, neural processing, and animal behavior interact to enhance signals for communication and detection and to reduce signals for chemical camouflage.

化学信号维系着绝大多数生命过程，包括生物间的相互关系。化学信号的检测不仅需要识别一系列独特的化合物或化合物混合物，还需要解析其空间与时间分布特征。信号的光谱与时间处理过程共同决定了何为有效信号，何为背景噪声。每种动物都会从化学环境中获取专属信息，并反过来为该环境贡献独特的化学信号。
龙虾已成为时间维度信号处理研究的重要模型生物。借助高时空分辨率的海洋化学信号检测技术，我们得以窥见龙虾生存环境的全新面貌。龙虾的化学感受器细胞（chemoreceptor cell）拥有4Hz的闪烁融合频率（flicker fusion frequency），能够在200毫秒的时长内整合刺激信号，这与龙虾以4Hz频率进行"嗅探"的气味采样行为高度匹配。基于这一特性，可通过对湍流扩散典型特征的气味斑块进行时间维度分析，还原空间气味梯度分布。龙虾似乎正是利用这一机制来定位气味源。
龙虾的社会行为高度依赖化学信号。尿液携带着求偶、等级支配以及个体识别所需的关键信息。肾孔（nephropore）处发现的一种全新腺体，其位置恰好可将分泌物释放入尿液中。随后尿液会被注入鳃流中，该水流可将尿液喷射至龙虾前方1至2米的位置。龙虾可调控三种不同的水流，以此实现化学信号的收发。
气味动力学的研究尚处于起步阶段。未来若能厘清信号扩散、感受器时间调谐、神经处理与动物行为之间的相互作用机制，将如何优化用于通信与探测的信号，并减弱用于化学伪装的信号，这无疑将是一项极具价值的研究方向。