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Malti🟢 Amoeba Phagocytosis
A deformable amoeba senses a chemoattractant gradient from nearby food particles, extends actin-driven pseudopods toward it, and engulfs prey on contact to form a digestive vacuole.
How it Works
The amoeba's membrane is drawn as 32 control points spaced evenly around a moving center, each holding its own radius offset. Every frame the simulation sums a chemoattractant vector from all nearby food particles, approximating each particle's field as inversely proportional to squared distance, exactly like a diffusing chemical signal sampled close to its source. Control points whose outward direction aligns with that net vector are pushed toward an extended target radius at the actin extension speed, while points facing away relax back toward the base radius, so the whole outline bulges into a pseudopod on the food-facing side and the amoeba visibly crawls in that direction as its center drifts along the same vector.
A smooth closed curve is drawn through the 32 points using quadratic curves between successive midpoints, which keeps the membrane looking soft and amorphous rather than faceted. When the amoeba's boundary radius at the angle toward a food particle reaches or passes that particle's distance from the center, the food is engulfed: it is removed from the field, a shrinking, fading vacuole marker is spawned inside the cytoplasm to represent the digestive vacuole, and the engulfed-particle counter increments.
Point influence: infl_i = dot(dir_i, A)
Target radius: target_i = base + max(0, infl_i) · gain
Extension: r_i += (target_i - r_i) · extensionSpeed
Engulf when: dist(center, food) ≤ r_i(angle to food) + foodRadius
Frequently Asked Questions
What is phagocytosis?
Phagocytosis is a form of endocytosis in which a cell engulfs a large particle, such as a bacterium or food source, by wrapping its membrane around it and pinching off an internal vacuole. Amoebae use it to feed, and immune cells like macrophages use it to destroy pathogens.
What is chemotaxis and how does the amoeba use it?
Chemotaxis is directed movement along a chemical concentration gradient. In this simulation the amoeba sums an attraction vector from every nearby food particle, weighted by inverse-square distance, and biases its pseudopod extension toward the strongest net direction.
What is a pseudopod and how is it modeled here?
A pseudopod is a temporary, actin-driven protrusion of the cell membrane that amoebae extend to crawl and capture prey. The simulation models the amoeba's edge as many control points that individually extend outward when they face the food direction and relax back otherwise, creating a bulging, crawling motion.
How does actin drive pseudopod extension in real cells?
Actin monomers polymerize into branching filament networks just under the cell membrane on the side facing an attractant, physically pushing the membrane outward. When the chemical signal fades, the actin network disassembles and that region of membrane retracts.
What happens to a digestive vacuole after engulfment?
After a food particle is engulfed, it sits inside a membrane-bound vacuole where digestive enzymes break it down over time. In the simulation each vacuole marker shrinks and fades over several seconds to represent this digestion process.
About this simulation
Thirty-two control points ring the amoeba's center, each independently deciding whether to push outward or relax back based on a single dot product with the summed chemoattractant field from every food particle on screen. There is no pre-drawn pseudopod shape — watching the membrane bulge, round off into a smooth crawling front, and swallow a bacterium whole shows how a cell with no eyes or brain can still hunt down a moving target using nothing but local chemical gradients.
🔬 What it shows
A soft-bodied amoeba that senses an inverse-square chemoattractant field from scattered food particles, extends its membrane toward the strongest signal, and engulfs prey into shrinking digestive vacuoles on contact.
🎮 How to use
Click anywhere on the canvas to drop extra food, then tune Chemotaxis Sensitivity and Actin Extension Speed to change how sharply the amoeba chases it; adjust Food Spawn Rate and Amoeba Base Size to change the pace and scale of the hunt.
💡 Did you know?
Amoeboid crawling and phagocytosis use the same actin machinery that human white blood cells use to chase down and engulf bacteria, which is why immune cell movement looks so similar to a free-living amoeba's.
Frequently asked questions
What is phagocytosis?
Phagocytosis is a form of endocytosis in which a cell engulfs a large particle, such as a bacterium or food source, by wrapping its membrane around it and pinching off an internal vacuole. Amoebae use it to feed, and immune cells like macrophages use it to destroy pathogens.
What is chemotaxis and how does the amoeba use it?
Chemotaxis is directed movement along a chemical concentration gradient. In this simulation the amoeba sums an attraction vector from every nearby food particle, weighted by inverse-square distance, and biases its pseudopod extension toward the strongest net direction.
What is a pseudopod and how is it modeled here?
A pseudopod is a temporary, actin-driven protrusion of the cell membrane that amoebae extend to crawl and capture prey. The simulation models the amoeba's edge as many control points that individually extend outward when they face the food direction and relax back otherwise, creating a bulging, crawling motion.
How does actin drive pseudopod extension in real cells?
Actin monomers polymerize into branching filament networks just under the cell membrane on the side facing an attractant, physically pushing the membrane outward. When the chemical signal fades, the actin network disassembles and that region of membrane retracts.
What happens to a digestive vacuole after engulfment?
After a food particle is engulfed, it sits inside a membrane-bound vacuole where digestive enzymes break it down over time. In the simulation each vacuole marker shrinks and fades over several seconds to represent this digestion process.
A deformable amoeba senses a chemoattractant gradient from nearby food particles, extends actin-driven pseudopods toward it, and engulfs prey on contact to form a digestive vacuole.
2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install