The Fluid Felines. New Research Shows Cats Can Flow Like Liquids


For generations, experienced cat owners as well as curious physicists have made observations that challenge our basic understanding of states of matter. Specifically, many have declared that felines seem to defy the expected behaviors of solids and fluids. In 1999, physicist Marc-Antoine Fardin even proclaimed that “Cats are liquids”. Witnesses report seeing cats flowing into tight spaces, spreading out to fill containers, and changing shape while retaining constant volume. This strange phenomenon has led some to jokingly suggest cats constitute an exotic fifth state of matter beyond solids, liquids, gases, and plasma. In this article, we’ll explore the scientific explanations behind cats’ apparent liquid tendencies.

The Science Behind Cats’ Liquid Abilities

Cats have unique anatomical features that allow them to contort their bodies and fit into incredibly small spaces. According to scientific research, cats have flexible backbones and shoulder blades that are not attached to their shoulder muscles (1). This allows cats to change the shape of their shoulders, compress their rib cages, and maneuver their front and hind legs independently to squeeze through tight gaps (2).

In addition, cats have lightly built, small, and loosely connected collar bones compared to other mammals (3). Their smaller and more flexible skeletons give them great agility to twist, turn, and alter their shape. A study found adult cats can fit through gaps as small as 6 cm high and 4 cm wide (1). Kittens can fit into even tighter spots due to their tiny size and high flexibility.

Scientists have researched how the special anatomy of cats allows them to achieve their liquid-like abilities to conform to containers and tight spaces. Their amazing compressibility and range of motion enable cats to temporarily morph their bodies to flow into small openings and take on the shape of whatever unique space they occupy.


Cats’ Skeletons and Joints Enable Liquid Movements

Cats have extremely flexible skeletons that allow them to effortlessly twist, turn, and squeeze into tight spaces. According to Cornell University College of Veterinary Medicine, cats’ vertebrae are connected very flexibly and have cushioning disks between them that are particularly elastic. This allows their spines to bend and stretch easily. Cats also have loose shoulder joints that permit their front legs to move freely in all directions. Their hip joints are similarly unrestricted, enabling hind leg motions that make cats appear to not have bones at all.

Additionally, cats have a large number of vertebrae in their spines, ranging between 50-53, compared to only around 34 in humans. With so many vertebrae acting like spools on a string, cats can arch their backs and twist their bodies in remarkable ways. Their vertebrae and interconnected bones provide great shock absorption as cats jump from high places. This flexibility helps cats fit into any container or space, no matter how small or oddly shaped. When combined with their playful personalities, cats’ flexible skeletons are what give them their reputation for liquid-like fluidity.

Cats’ Personalities Contribute to Liquid Behavior

Cats are naturally very curious creatures. According to Rover, kittens tend to be especially curious as they explore and learn about their environment. This innate curiosity leads cats to investigate every nook and cranny. As stated by Nutrish, “A cat’s curiosity is born out of a natural instinct to assess their environment for prey and predators.”

This exploratory nature causes cats to end up in some very tight spaces that their liquid abilities allow them to navigate. As explained by the Cat Behavioral Alliance, “A cat’s curiosity is a mix of her natural instincts that have evolved over many thousands of years.” Their flexibility enables them to follow their curiosity into small, confined areas that other animals cannot access.

In addition to curiosity, cats are often playful and adventurous. They love to explore their surroundings and challenge themselves by climbing, jumping, and squeezing into tight spaces. Their liquid-like maneuvers through tricky areas are aided by their bold and daring personalities.

Examples of Cats Acting Like Liquids

One of the most amusing and endearing examples of cats behaving like liquids is their ability to contort their bodies to fit into very small spaces. As the old adage goes, “if I fits, I sits!” Cats seem to embody this perfectly, defying physics by morphing their supple, flexible bodies to fit into boxes, vases, baskets and more. Their liquid-like maneuverability allows them to curl up and make themselves comfortable in the tightest of quarters.

There are countless hilarious gifs and images online showing cats squeezing themselves into improbably small containers and spaces. In one gif, a ginger cat determinedly wedges itself into a narrow cardboard box, its body conforming perfectly to the box’s dimensions1. In another, a fluffy black and white cat pours itself into a vase, curling up snugly with its tail sticking straight up out of the top2. No space is too small for an ambitious, liquid-esque cat!

These viral gifs and images demonstrate how cats can flatten, mold, and pour themselves to fit, no matter how puzzling it seems to humans. Their body fluidity and determination to fit in snug spaces is one of the most iconic examples of cats’ apparent “liquid” abilities.

The Nobel Prize Connection

In 2015, American researcher Marc-Antoine Fardin received the Ig Nobel Prize in physics for his paper titled “On the Rheology of Cats,” which was published in the journal Rheology ( The Ig Nobel Prizes honor scientific achievements that “first make people laugh, and then make them think.” Fardin’s paper explored the idea that cats can behave like liquids, examining how they use their elasticity and flexibility to fit into tight spaces.

Fardin’s work stemmed from observing his cat squeeze under a small gap in a fence. Intrigued by cats’ ability to conform to containers, he applied principles of rheology – the study of the deformation and flow of matter – to investigate this “liquid” behavior in cats. Through physics equations and experimentation, he showed that cats can alter their shape to fit openings as small as their shoulder width. This ability is enabled by cats’ loose skin, compressible torso, and highly flexible bones and joints.

While humorous, Fardin’s Ig Nobel Prize research highlighted the practical applications of studying cats’ liquid capacities. It could aid veterinary medicine, help design comfortable cat carriers, and provide insight on feline behavior and anatomy. The work reminds us that playful scientific curiosity can lead to meaningful discoveries.

Practical Applications of Research

One of the most well-known practical applications of research on cats’ fluid tendencies is in designing cat furniture and toys. Cat furniture designers take advantage of cats’ ability to fit into small spaces and contort their bodies by incorporating tunnels, hiding spots, perches, and multi-level platforms into their products. For example, this cat tree design uses multiple carpeted platforms connected by sisal rope so cats can climb and lounge. The platforms are made with plywood for sturdiness but can be tightly spaced thanks to cats’ liquid nature.

Interactive cat toys also often require cats to twist, turn, stretch, and reach using their flexible spines and limbs. For instance, the interactive cat furniture designed by J. Ai includes moving parts for cats to play with that require them to utilize their liquid tendencies. Understanding the science behind how and why cats can fit into and interact with unique structures enables companies to create entertaining and enriching products for pet owners’ feline companions.

Risks of Cats’ Liquid Tendencies

While cats’ ability to fit into tight spaces is impressive, it can also be dangerous. Owners need to be aware of the risks.

Cats can squeeze into very small areas, but sometimes have trouble getting back out. This could lead to a cat getting stuck in a tight space like behind furniture or inside of appliances (reference A trapped cat may panic or get injured trying to escape.

Cats may also crawl into unsafe areas their owners are unaware of. Small spaces inside homes can contain hazards like exposed wires, chemicals, or broken glass that could harm a curious cat (reference

Owners should cat-proof their homes by sealing off dangerous areas. Monitoring cats closely can also help avoid accidents. While their liquid abilities are cool, owners must take precautions for their cats’ safety.

Tips for Cat Owners

As a cat owner, it’s important to keep your cat’s liquid abilities in mind and take proper precautions. Here are some tips:

Supervise your cat around ledges, small spaces, or high areas where they could pour themselves into dangerous places. Cats can fit into incredibly small crevices so be vigilant.

Cat-proof your home by keeping doors closed, covering openings, and securing chemicals or medications up and away from your cat’s reach. Liquids can get into the tiniest spots.

Take care when giving your cat oral medications. Mixing meds into their food or treats is an easy way to administer it, according to Just be sure to consult your vet.

Invest in puzzle feeders or activities to keep your liquid cat entertained and mentally stimulated when you’re away.

Pay attention to your cat’s body language and provide plenty of cozy beds, cat trees, and scratching posts so they can relax in their preferred liquid state.


Cats’ uncanny ability to mold and squeeze themselves into and out of tight spaces, almost shape-shifting, has led many to characterize them as acting like a liquid. Feline spines with over 50 vertebrae and highly mobile joints allow cats to achieve contortionist positions. Additionally, their independent personalities encourage behaviors seeking comfort and stimulation with no regard for human meaning of physical space. While research into the complicated biology behind these liquid-like movements is still underway, it has already led to advances in soft robotics and flexible materials engineering. Cat owners can make use of studies on cat flexibility to better understand safe spaces for their pets. Overall, cats continue to fascinate humans with their otherworldly locomotion and soup-like embodiment.

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