noun
long-armed octopus (Octopus minor)
A small octopus species with long arms, found in East Asian waters. The name is usually written in katakana as テナガダコ.
テナガダコは、腕が長くて細いのが特徴です。
The long-armed octopus is characterized by its long, slender arms.
From 手長 (てなが, 'long-armed') + 蛸 (たこ, 'octopus'). The exact derivation is straightforward; the kanji spelling is rarely used.