Why Cats Defy the Laws of Liquids (And Always Land on Their Feet)


It’s a common joke on the internet that cats are liquid or behave like a liquid. Videos and images showing cats taking the shape of containers they’re in or squeezing into tight spaces seem to “prove” that felines must have liquid-like properties. Phrases like “cats are liquid” get frequently repeated in meme culture. But scientifically speaking, why can’t cats actually be liquid? Cats are complex living creatures and their anatomy is quite different from the molecular structure of liquids like water. This article will explore the interesting question of why cats can’t literally be liquid in a factual, scientific way.

According to a joke study published in the humor journal Improbable Research, feline rheology (the study of deformation and flow) supports the perception that cats are liquid. But real physics shows cats do not have the properties of liquids like water. Their behavior just makes them seem fluid-like to our human eyes sometimes. The intriguing and funny perception that cats are liquid reveals an amusing misunderstanding of feline anatomy, states of matter, and how chemical bonds work on a molecular level.

Anatomy of Cats

Cats have a skeletal structure made up of bones that give their body a solid form. Like other mammals, cats have a skeletal system comprised of around 230 bones. Some key bones include the skull, rib cage, spine, shoulders, hips, legs and tail (Cat anatomy).

In terms of muscles, cats have well-developed muscles throughout their body that aid in movement and provide strength and agility. Key muscle groups include the chest, shoulders, back legs and neck. Cats also have a muscular tongue and digestive system to aid in eating and digestion.

The major organs in a cat’s body are the heart, lungs, liver, kidneys, stomach, intestines, brain, eyes, ears and skin. This complex network of organ systems allows cats to circulate blood, breathe, digest food, remove waste, sense the world around them, control body movements and regulate bodily functions (2021 Ultimate Veterinary Guide to Cat Anatomy with Images).

In summary, a cat’s anatomy including its skeletal structure, muscles and organs gives it a solid, defined form that is distinctly non-liquid.

States of Matter

Matter exists in three main states – solid, liquid, and gas. Solids have a defined shape and volume that cannot be easily changed. The molecules in a solid are packed closely together and vibrate in place rather than move freely (wikipedia). Liquids have a defined volume but take the shape of their container. The molecules in a liquid are packed closely but can slide past each other and move around. Gases do not have a defined shape or volume; their molecules are spread far apart and move freely (Lumen Learning).

Cats’ bodies are composed of solid matter. Their bodies have a defined shape and volume that does not change easily. The molecules and atoms that make up a cat’s physical form are tightly packed together, giving their bodies a solid structure.

Chemical Bonds

Cats, like all animals, have different types of chemical bonds that hold their molecules together in a solid state. The main chemical bonds found in animals are covalent and ionic bonds 1. Covalent bonds involve sharing electrons between atoms, while ionic bonds form through electrostatic attraction between ions of opposite charge.

Proteins like collagen contain many covalent bonds, formed when amino acids link together to create polypeptide chains. These chains then twist into helical structures stabilized by hydrogen bonds 2. The hydrogen bonds between protein chains are relatively weak compared to covalent bonds. However, collectively these many weak bonds have a significant effect, helping maintain the solid structure of tissue, bone, and cartilage.

Ionic bonds also play a key role. For example, calcium ions in bone link with phosphate ions to create calcium phosphate crystals, providing strength and rigidity. Overall, the combination of various chemical bonds at the molecular level is what keeps a cat’s body in a non-liquid, solid physical form.

Surface Tension

Surface tension is a property of liquids arising from the molecules at the surface being subjected to unbalanced cohesive forces from the liquid molecules beneath them (Britannica, 2023; Wikipedia, n.d.). This results in the molecules arranging themselves to minimize surface area, creating an elastic-like force across the liquid’s surface. Water exhibits high surface tension due to the strong hydrogen bonding between its molecules (USGS, n.d.).

Cats are unable to maintain a liquid state like water because they lack the molecular cohesion that gives rise to surface tension. The molecules and cells comprising a cat’s anatomy are not attracted to each other strongly enough to form a cohesive surface layer. A cat’s body also has discernible shape, volume, and structure rather than complete freedom of motion like liquid water. Strong surface tension allows smaller volumes of water to resist deformation into droplets, while a cat’s anatomy does not have this tensile strength.

In summary, the molecular forces between water molecules create surface tension, which helps water maintain a liquid state. Cats lack comparable molecular cohesion, so they cannot resist forces and maintain a liquid shape like water does.

Cat Behavior

Cats exhibit many interesting and sometimes peculiar behaviors. One such quirky behavior that gives cats an almost “liquid-like” quality is their tendency to curl up in boxes, vases, bowls, and other small spaces.

According to 15 Strange Cat Behaviors Explained, cats like to squeeze into tight spaces because it makes them feel safe and secure. In the wild, confined spaces gave cats a place to hide from predators and threats. Domestic cats retain this instinctual behavior.

When curling up into a tight ball, a cat is able to mold its body to fit the shape of its container, not unlike the way a liquid takes the form of its vessel. A cat’s flexible spine allows it to occupy spaces much smaller than its normal size would suggest. This ability to seemingly “flow” into nooks, boxes, and crannies is a uniquely feline trait that adds to their mystique.

So while cats can’t literally turn into liquids, their ability to contort themselves into fluid arrangements gives them an almost supernatural, shape-shifting quality. When your cat curls up in a box or basket, it’s easy to see how they give off the illusion of “liquid cat.”

Liquid Cat Pranks

The concept of cats as liquids has become a popular internet meme, with viral videos and images portraying cats flowing like water in unlikely positions and fitting into impossibly small spaces. While some of these are clever photo edits, many feature actual feline flexibility and predilection for squeezing into tight areas.

Some of the most well-known examples include images of cats peering out of vases as if poured inside, cats flattening themselves inside dresser drawers, and the iconic meme of a cat sitting in a glass with the text “I can haz fitz”.

Videos tend to attract the most views and shares online, with compilations of cats walking through domino chains as if the dominoes were not there, cats slinking smoothly under doors, and owners manipulating sleeping cats into liquid-like positions.

The most viral feline liquid prank videos stem from owners gently placing cats through obstacles courses of varying complexity. Despite interruptions like slipping through railings or crawling under barriers, the cats manage to remain placid, often sitting down casually afterwards as if it was completely normal.

While these playful pranks exaggerate cats’ impressive agility and chill temperament, they showcase an element of truth about feline anatomy and abilities. The internet fame of liquid cats ultimately stems from amused owners witnessing their pets’ silly antics and flexibility firsthand.

As one widely shared video proves, some cats really do appear to defy physics. https://www.youtube.com/watch?v=gsRmtm-ilNY

Cats vs Other Liquids

Cats and liquids like water have some similarities but also key differences. Liquids like water take the shape of their container and flow to fill the space available. Cats can exhibit liquid-like behavior in that they seem to relax their skeletal structure and flow into containers when given enough time, as noted byMarc-Antoine Fardin’s research that won an Ig Nobel Prize (https://www.pbs.org/newshour/science/answering-the-question-that-won-me-the-ig-nobel-prize-are-cats-liquid). However, unlike true liquids, cats maintain some rigidity in their structure and cannot change their volume. Cats can fit into tight spaces when relaxed, but their underlying bone structure does not dissolve entirely like a liquid. A key difference is that the molecular bonds in water are very weak, allowing the molecules to flow past each other easily. Cats’ molecular bonds in tissues like muscle are much stronger in comparison. So while cats may sometimes appear liquid-like, their molecular bonds still maintain a soft but solid cat structure.

Why It Matters

Though scientifically incorrect, the idea of cats being liquid has important implications. This metaphor highlights cats’ incredible agility and flexibility allowing them to adapt their bodies to fit into seemingly impossible spaces. Their “liquidity” enables behaviors like squeezing into boxes and vases for play or to feel secure. The liquid cat metaphor also reveals people’s delight in cats’ silly antics and desire to understand their enigmatic nature. While not literally true, the concept underscores charming cat traits that make them beloved pets.

More philosophically, the notion of liquid cats speaks to reconciling scientific rigor with imaginative interpretations of the world. While physics may definitively prove cats are not liquids, creative descriptions capture truths about cats’ essence in a playful, thought-provoking way. Our enthusiasm for liquid cats demonstrates the human impulse to seek meaning through metaphor. So while scientifically misguided, the liquid cat idea discloses deeper emotional and psychological truths about humanity’s relationship with companion animals.


In summary, while cats often appear to exhibit liquid-like behaviors and can contort their bodies in fluid ways, their underlying anatomy and chemistry means they are scientifically classified as solids rather than liquids. Cats have a defined skeletal structure and their tissues and cells are held together by chemical bonds that maintain their form. Though they can flow gracefully and ‘pour’ themselves into containers, this is enabled by features like loose skin, flexible joints, and instinctual behaviors – not an innate liquid state.

Some online communities and social media users have advanced the fun theory that cats are liquid as an amusing thought experiment. However, evaluating cats through the lens of physics, chemistry, and biology makes clear they do not actually meet the scientific definition of a liquid. Their flowing, liquid-seeming movements are better understood as a product of evolution and feline agility. While evocative and whimsical, the idea that cats are liquid remains more metaphor than scientific reality.

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