Although recent studies have shown that phenotypic variation among individuals potentially has a strong influence on ecological interaction, most ecological studies still assume explicitly or implicitly that individuals show a uniform phenotype. Daphnia species provide a model system for studying the phenotypic variation, because they are known to show remarkable morphological plasticity in response to their predators. We conducted a laboratory experiment to examine the intra-specific variation in morphological plasticity of the two daphnids: Daphnia pulex (large adult size) and D. ambigua (small adult size) in response to two different predators (Chaoborus larvae and fish). We hypothesized that the daphnids exhibit distinctive plasticities depending on their body size, because visually-hunting fish and gape-limited Chaoborus larvae prefer large and small sized prey, respectively. However, our results suggested no clear relationship between body size and morphological plasticity as predicted. Although the two daphnids indeed overlap their body size, they showed different induced morphologies even if individuals with a similar body size were compared between the two species. Such variations should bring about a wide range of adaptive responses against different predators.