Octopus: the Master of Disguise

I woke up early to go to Costa da Caparica.

It's a good spot for snorkeling in the summer and is a 15-minute drive from my house in Lisbon.

The water was a little cold, but the visibility was good.

I found an octopus and dove in to observe it.

It didn't run away very far, but what I found strange was that it was disguised as the color of the rock, and when I got very close, it turned white and adopted a different shape, like a star.

I did a second dive, and it behaved exactly the same way; I even noticed that its texture changed when it turned white.

It didn't make sense to me that it would lose its camouflage of the rock's color.

Until I realized what it was doing: it was disguising itself as a starfish.

This is a defensive mimicry strategy, since there are starfish of that color in the area.

Why the octopus behaved this way:

What I witnessed that morning was a remarkable example of octopus camouflage and mimicry, two of the most advanced survival strategies in the animal kingdom.

Octopuses have specialized skin cells—chromatophores, iridophores, and leucophores—that allow them to instantly change color, brightness, and even texture. This means they’re not only able to blend in perfectly with sand, rocks, or reefs, but also mimic the patterns and shapes of other marine animals.

In this case, the octopus first opted for rock camouflage, blending into the background to remain unnoticed. But when I came too close, it switched tactics. Instead of continuing to match the rocks, it shifted into a dramatic white form with star-like arms, imitating a starfish. This type of quick disguise is a form of defensive mimicry: by resembling a less appealing or less threatening species, the octopus reduces the likelihood of being attacked.

It might seem counterintuitive that the octopus would “drop” its perfect rock camouflage. Still, the logic is that when an intruder (in this case, me) gets too close for camouflage to be useful, mimicry becomes the better strategy. A predator might hesitate to attack what it perceives to be a starfish, which is spiny and not particularly appetizing to most hunters.

What amazed me is that the octopus didn’t just change color—it also altered its texture and body posture, raising its arms to look less like an agile mollusk and more like the rigid, radial body of a starfish. This shows why octopuses are often described as the “shape-shifters of the sea.”

The encounter was a small, real-life glimpse of the extraordinary intelligence of these animals. Octopuses don’t just rely on reflex—they seem to make context-based decisions, choosing between camouflage, mimicry, or escape depending on the situation. 

watch the video: