Octopus mirror tests are rare in marine science, and this one comes with a genuinely clever setup: put a piece of prey behind an octopus where it can't see it directly, then give the octopus a mirror as its only way to spot that prey. Will it figure out the reflection isn't the real thing, and if so, how long does that take? In this Ocean Decoded Live clip, we break down a study on Octopus bimaculoides (the California two-spot octopus) that put exactly that question to the test, and the results say a lot about how these animals actually think.

Researchers credited in this segment as Mary Kieseler and Peter Tse at Dartmouth built a tank with a start chamber, a mirror positioned at the tank's midline, and a barricade blocking the octopus's direct line of sight to its prey, so a reflection was the only visual cue available. In the earliest trials, the octopus reliably moved toward the crab's reflection in the mirror as if it were real prey, and showed no reaction to the actual live crab when it entered view nearby. But after reaching the mirror and finding nothing there, the octopus began redirecting toward the real prey instead, a shift researchers say took roughly 10 to 12 trials per animal to learn consistently. That learned pattern, the study argues, points to genuine executive control over hunting behavior rather than a fixed, reflexive response to any visual stimulus that looks like prey.

The octopuses also got measurably better with practice: over repeated trials, they traveled shorter distances per correct trial and touched the mirror less often before locating the real prey, a clear sign of improving navigation efficiency rather than random trial and error. It's one more data point in a growing pile of evidence that octopuses are remarkably capable problem solvers, and it's a fun one to end on after a heavier conversation about underwater data centers earlier in the show. If you want more ocean science broken down like this, Ocean Decoded Live streams Monday through Thursday, 4:00–6:00 PM Eastern, hosted by Andrew Lewin. Subscribe and hit the bell so you don't miss it, and thanks for watching.

Chapters:
0:00 Hook: Can an Octopus Catch Prey It Can Only See in a Mirror?
0:14 Welcome to Ocean Decoded Live Clips
0:56 Meet Octopus bimaculoides and the Mirror Test
1:24 The Setup: Prey Hidden, Visible Only Through the Reflection
1:43 The Dartmouth Researchers Behind the Study
2:21 Chasing the Reflection vs. Finding the Real Crab
2:53 The Results: Learning to Ignore the Mirror
4:05 Inside the Experiment: Tank Setup and Trial Design
5:11 Navigation Gets More Efficient With Experience

Takeaways:

A study on Octopus bimaculoides (the California two-spot octopus) tested whether the animals could use a mirror to locate prey they couldn't see directly, credited in this clip to researchers Mary Kieseler and Peter Tse at Dartmouth.

In early trials, the octopus moved toward the crab's reflection in the mirror as if it were real prey, and ignored the actual live crab when it appeared nearby.

After reaching the mirror and finding no prey there, the octopus learned to redirect toward the real prey instead, a shift researchers say took about 10 to 12 trials per animal.

The study's authors frame this learned inhibition as evidence of executive control over hunting behavior, not just a fixed reflex to any prey-like visual stimulus.

Octopuses also got more efficient with practice, traveling shorter distances per correct trial and touching the mirror less as trials went on.

The host ties the finding to a broader point about octopus intelligence and tool use in hunting contexts.

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