Data from: The mouth morphology of diving beetle Hyphydrus japonicus (Dytiscidae: Hydroporinae) is specialized for predation on seed shrimps

Two-shelled organisms, such as bivalves and seed shrimps, protect themselves from external stresses by firmly closing both shells. We found that the diving beetle Hyphydrus japonicus Sharp, 1873 (Dytiscidae: Hydroporinae) larvae frequently prey on seed shrimps. Other predatory aquatic insects have difficulty in capturing seed shrimps owing to the general form of their mandibles. Larvae of H. japonicus bear a projection on the head (the nasale), which is used in conjunction with vertical movements of the mandibles to fixate the valves of their prey and gain access to the soft body within them. This capture method does not destroy shells and is extremely efficient. The present study provides the first report on the use of a unique morphological trait for attacking prey animals without destroying their shells.

双壳生物（如双壳类（bivalves）与介形虫（seed shrimps））可通过紧密闭合双壳抵御外界胁迫。本研究发现，日本异爪龙虱（Hyphydrus japonicus Sharp, 1873，龙虱科（Dytiscidae）：水纹龙虱亚科（Hydroporinae））的幼虫常捕食介形虫。其余掠食性水生昆虫因颚部结构常规，难以捕捉介形虫。日本异爪龙虱幼虫头部具有突起结构（nasale，鼻突），该结构可配合颚部的垂直运动，固定猎物的双壳，从而得以获取其体内的软组织。此种捕食方式不会破坏猎物双壳，且效率极高。本研究首次报道了利用独特形态特征，在不破坏猎物外壳的前提下对猎物发起攻击并取食的相关策略。