giant Pacific octopus vs great hammerhead

The largest octopus species, with three hearts, blue blood and about 2,000 suckers. The largest hammerhead, whose broad head spreads its electroreceptors for finding buried rays. On the measurements below, great hammerhead leads on more of them — but they do not all point the same way, and the ones that disagree are the interesting part.

The measurements

Where each one leads

• Mass: great hammerhead is 15× heavier.
• Lifespan: great hammerhead is 7.5× a longer life.

What this does and does not tell you

These are measured averages with real ranges behind them, and every figure links to its own page. What they cannot do is settle an encounter. Outcomes between animals turn on circumstance — who initiates, whether either is hungry, defending young, injured or cornered, and what the terrain favours. Size and bite force are not decisive on their own, and most of these pairs never meet in the wild in any case, because their ranges do not overlap.

Every figure here is an average with a substantial spread. Individual animals vary enormously — a large individual of the smaller species routinely exceeds a small individual of the larger one.