Imagine yourself underwater, watching an octopus slowly emerge from the shadows. At first, it looks like a puddle of liquid, shapeless and calm, then suddenly, with a subtle shift, it molds itself to the rocks beneath. You blink… and it’s gone, jetting away in a blur of water.

On World Octopus Day, there’s no better time to dive into the mysteries of these mesmerizing creatures. How does an octopus manage to be fluid, invisible, and fast all at once? Welcome to the octopus’s world, where mastering flow is the secret to thriving.

I. The Fluid Body: A Master of Viscosity

Octopuses are nature’s ultimate shape-shifters. Their bodies transition from formless masses to stable shapes in the blink of an eye. Imagine the octopus as a “viscous entity”, flowing and spreading like a liquid when it hides or squeezes into tight spaces, yet firming up for stability when needed. Much like a puddle that takes shape with purpose, the octopus morphs from a squishy blob into a stealthy predator, always knowing when to remain fluid and when to stand firm.

This fascinating ability is tied to viscosity, how a substance resists flow. The octopus mimics a liquid with variable viscosity: slipping through cracks with the ease of a low-viscosity fluid, yet holding its shape like a more viscous material when stillness or control is essential. It doesn’t just fit the mold, it becomes the mold. By shifting its viscosity at will, the octopus glides effortlessly through its environment, adapting to any challenge with its unique, fluid approach to life.

II. Blending into the Flow

Beyond its fluid body, the octopus has a masterful trick up its sleeve, camouflage that extends beyond mere color changes. By adjusting both its shape and movement, it blends seamlessly into the water, becoming one with the surrounding currents. The ocean isn’t just its playground, it’s the perfect cloak, where streamlines become the octopus’s secret weapon for invisibility.

Streamlines are the smooth paths fluids follow as they flow around objects. The octopus, with its flexible body, aligns itself with these paths, minimizing any disruption to the surrounding water. In this way, it doesn’t just move through the water, it moves with it, creating no more disturbance than a gentle ripple. By merging into the currents, the octopus becomes almost invisible to both predators and prey.

Engineers use the same principle when designing streamlined surfaces for airplanes and submarines, reducing disruptions in fluid flow for greater efficiency. For the octopus, blending into the flow is more than a survival tactic, it’s an art. By becoming one with the water, it disappears into its environment without creating chaotic ripples or drawing attention to itself.

III. Jet Propulsion: Speed in Silence

When blending in isn’t enough, the octopus switches from quiet invisibility to sudden speed. Using jet propulsion, it can escape danger with the efficiency of an underwater rocket. But while human-engineered jets come with noise and exhaust, the octopus performs its escape with silent precision.

Here’s how it works: The octopus draws water into its mantle and expels it through a narrow siphon, propelling itself forward in a perfect demonstration of Newton’s third law of motion: for every action (expelling water), there’s an equal and opposite reaction (the octopus shooting forward). What sets the octopus apart is the quiet grace of its movement. No noisy jets, no fiery exhaust; just a smooth, silent burst of water that sends it gliding through the ocean in a blur.

With the fluid grace of its jet propulsion system, the octopus leaves behind nothing but a swirl in the water; proof that sometimes, the quietest escapes are the most effective.

Conclusion: The Perfect Flow

Octopuses aren’t just creatures of the ocean, they’re masters of its currents. Whether they are mimicking a shapeless mass, blending into water’s streamlines, or jetting away with swift elegance, these fascinating animals show us how to adapt seamlessly to the rhythms of the sea. In their world, thriving means flowing with the water rather than against it.

And when it’s time for a dramatic exit, the octopus adds a final flourish: a burst of ink that diffuses through the water in chaotic swirls. This isn’t just a distraction, it’s a parting signature, giving the octopus enough time to disappear, leaving the ocean stirred and yet unchanged. Like the final stroke of an artist’s brush, the ink dissolves into the water, completing the octopus’s fluid performance.

In the octopus’s realm, success depends on mastering when to flow, when to stay still, when to vanish, and when to leave a mark. If outmuscling the world isn’t an option, the octopus reminds us: sometimes the answer is to outflow it.

💧 Flow Check 💧

Here’s a quick dive into the fluid dynamics concepts that make the octopus a master of currents:

• Viscosity: The octopus manipulates its body’s viscosity, flowing like a liquid through tight spaces while firming up when stability is needed.
• Streamlines: It moves with the ocean’s currents, aligning with streamlines to minimize disturbances in the water, making its movements nearly invisible.
• Jet Propulsion: Using Newton’s Third Law, the octopus propels itself forward by expelling water through its siphon, achieving silent, swift movement.

🌊 Rogue Wave 🌊

Ready to channel your inner octopus? Try these challenges and dive into the flow:

• Can you mimic the octopus’s flexibility? Try moving through a space as smoothly as possible, avoiding any disruptions, just like an octopus slipping through tight cracks.
• Experiment with water and streamlines! Run your hand gently through a still pool of water; how close can you get to creating minimal ripples, mimicking the octopus’s stealthy movements?
• Catch the breeze. The next time you feel the wind, imagine it as a fluid current, like water. How would the octopus’s movements change if it were gliding through air instead of water?
• And for an artistic twist: leave your mark in a fluid medium. Whether it’s ink in water or food coloring in oil, can you create a swirling masterpiece like the octopus’s final flourish?

Dive Deeper

Social Currents:

• Elizabeth Preston (2024, September 23). Punching Octopuses Lead Fish on Hunting Parties. The New York Times.
• Michael Levenson (2024, April 11). The Joys and Challenges of Caring for Terrance the Octopus. The New York Times.
• Helen Scales (2024, April 4). ‘The finger-touch sent shivers down my spine’: my encounter with a common octopus. The Guardian.
• Nicola Davis (2023, July 3). This article is more than 1 year old ‘Not so alien’: biologist busts myths and explores enigma of the octopus. The Guardian.
• Elle Hunt (2023, March 30). Octopus farming turns my stomach – but are some species really more worthy than others? The Guardian.
• Ben Guarino (2019, March 2). Inside the grand and sometimes slimy plan to turn octopuses into lab animals. The Washington Post.

Fluid Dynamics:

• The New York Times (2015, April 21). How the Octopus Moves
• me3340 (2015, January 15). Squid Jet Propulsion
• Steve Brunton (2020, November 20). Data-driven nonlinear aeroelastic models of morp
• devinsupertramp (2013, February 18). Flyboard – Coolest Water Jet Pack EVER!!!

Photo by Stephanie Harlacher on Unsplash.

This article was crafted with a touch of AI to bring fluid dynamics to life.