Young reef octopuses do not slap every fish that gets close: a 2026 study found arm strikes concentrated in fast, defensive encounters with territorial fish, while interactions with nonterritorial followers lasted more than three times as long as the underwater fight-club exchanges

A young reef octopus probes coral rubble while fish gather around it. One fish trails behind, ready to seize prey flushed from a crevice. Another darts in to defend a patch of reef. To a casual observer, both are simply fish getting close. To the octopus, a new field study suggests, they are very different […]