Why do octopuses have eight arms?
For grown-ups: the science
Eight bendy arms help an octopus feel, grab food, move, and explore.
Octopuses are cephalopods whose eight muscular arms are lined with suckers. Their arms provide flexible movement, grasping, touch and chemical sensing, and handling of prey; much of the nervous system is distributed through the arms. The exact evolutionary history is complex, but eight arms are a defining inherited body plan of modern octopuses and related cephalopods.
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Transcript
An octopus glides over the ocean floor, with eight arms waving. Why does it have so many arms?
Each arm can bend, twist, and reach around rocks. This helps an octopus explore many places at once.
Little suckers line the arms and can grip tightly. They help the octopus hold food and feel what is nearby.
An octopus can use its arms to crawl, swim, and hide in snug spaces. Eight arms give it lots of ways to move and search.
So, an octopus has eight arms because they help it feel, grab, move, and explore its ocean home.