noun
flatworm
Refers to flatworms (phylum Platyhelminthes), including planarians and parasitic flukes. In everyday contexts, often written in kana.
ヒラムシは再生能力が高いことで知られている。
Flatworms are known for their high regenerative ability.
noun
flat bark beetle
Refers to beetles of the family Cucujidae. Usually written in kana.
ヒラムシの一種が樹皮の下で見つかった。
A species of flat bark beetle was found under the bark.
Compound of 平 (hira, 'flat') + 虫 (mushi, 'bug, worm'). The exact derivation is uncertain; the name simply describes the flat body shape.