Young animals, especially those developing within eggs, are extremely vulnerable to predation risk given their immobility, small size and limited functionality of developing sensory systems. Embryos from a range of taxa can detect predator cues and use antipredator responses to reduce risk; however, little is known about this capacity in elasmobranchs, especially regarding olfactory detection. Embryonic Port Jackson sharks (Heterodontus portusjacksoni) were exposed to elasmobranch and teleost odours across key developmental stages to investigate their capacity to detect and discern between cues. Oxygen uptake rates were measured as a proxy for antipredator response and to estimate their energetic costs. Earlier developmental stages exhibited limited responses, regardless of the odour, likely associated with an undeveloped sensory system. However, older shark embryos depressed oxygen uptake rates (i.e. crypsis responses) when exposed to teleost cues, but showed little response to elasmobranch cues. In contrast, hatchlings exhibited minimal responses to teleost cues but a significant increase in oxygen uptake rates when exposed to elasmobranch odours, indicative of a general stress response in preparation for escape. Collectively, our data suggest that embryonic sharks can differentiate between odour cues and elicit various responses, but this ability is limited by their developing sensory capacity.

幼小动物，特别是在卵中发育的幼小动物，由于其不活动，体积小以及发育的感觉系统功能有限，极易遭受捕食风险。来自各种分类单元的胚胎可以检测到捕食者的线索并使用反捕食者的反应来降低风险。然而，关于弹性分支机构的这种能力知之甚少，特别是在嗅觉检测方面。胚胎杰克逊鲨鱼（Heterodontus portusjacksoni）在关键的发育阶段暴露于弹性分支和硬骨的气味中，以研究其检测和区分线索的能力。测量氧气吸收率作为反捕食者反应的代理，并估算其能量消耗。无论气味如何，早期的发育阶段均显示出有限的反应，这可能与不发达的感觉系统有关。但是，年龄较大的鲨鱼胚胎在暴露于硬骨鱼线索时会降低氧气的吸收率（即低温反应），但对弹性分支线索几乎没有反应。相比之下，孵化场对硬骨鱼提示的反应最小，但是暴露于弹枝气味时氧气吸收率显着增加，这表明在准备逃跑时一般的压力反应。总的来说，