You’d be forgiven for thinking humans are the only architects on this planet; after all, the vast majority of things we see day-to-day are built by our own hands. But peer past the concrete, the steel, the plastic, and you’ll see a variety of spectacular structures we’ve had absolutely no hand in.
These structures are the works of other animals and their impressive designs often speak to a level of intelligence we rarely appreciate, not to mention a level of cooperation seldom seen in our own species. From makeshift ‘living’ rafts to dams visible from space, here are some of the strangest structures made by animals
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10 strangest structures made by animals
Octopolis (and Octlantis)
In 2009, divers discovered a rather peculiar site in Jervis Bay, Australia, that biologists later named ‘Octopolis’. This site, which is oval in shape, covered in discarded scallop shells, and roughly three metres in diameter, was (and still is, several generations later) home to more than a dozen gloomy octopuses (Octopus tetricus). These octopuses are usually solitary, so the fact that so many of them had taken up residence in a relatively small, shared space puzzled researchers.
Upon closer inspection, divers discovered a single piece of scrap metal at the centre of the site and concluded this had served as the original building block for the first pioneering octopuses to start building their scallop-covered ‘city’ upon.
As more scallops were eaten and their shells discarded at the edges of the site, the ‘city’ grew and more octopuses flocked to ‘Octopolis’. Interestingly, the shells appear to provide a much better building material for the octopuses to construct burrows in than the surrounding fine sand does.
Just a few hundred metres away, in 2016, a second gloomy octopus-built ‘city’ was discovered and named ‘Octlantis’.
Underwater ‘crop circles’
What lengths would you go to impress a potential mate? A male white-spotted pufferfish (Torquigener albomaculosus) will spend over a week carefully crafting elaborate ‘crop circles’ on the seafloor, all in a bid to attract a female that’ll appreciate his artwork.
These structures are typically 2m in diameter, which is more than 20 times the size of the pufferfish itself - the equivalent for us would be decorating a space roughly the size of a ferris wheel!
The male pufferfish doesn’t stop there. After constructing his ornate circular structure, he’ll decorate the ridges with shells and pieces of coral - items most females cannot resist. If a female pufferfish deems his creation worthy, she’ll swim into its centre and lay her eggs, which he’ll then guard until they hatch.
These strange underwater ‘crop circles’ were first noticed by divers in 1995, just off the coast of Japan’s Ryukyu Islands, but it wasn’t until 2013 when the white-spotted pufferfish was first discovered that they were finally attributed to the right artists.
Fungus farms
Both ants and termites are known for constructing giant nests capable of housing several million individuals. Inside these nests are elaborate tunnel networks connected to thousands of climate-controlled rooms, resembling a structure not too dissimilar to a London office block. While these structures are impressive, it’s the ‘fungus gardens’ some species of ants and termites cultivate inside of their nests that are truly mind-boggling.
- It can be seen from space and contains a staggering two hundred million mounds, each one nine metres across and two and a half metres tall
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More than 200 species of ants are known to farm fungus, and they do this by chewing leaves into a pulp before spreading it across their gardens to stimulate fungus growth. In the first few days of a new colony, the queen does all of the gardening work, fertilising her plot with fecal liquid.
After a few weeks, this messy work is passed onto the workers and fungus begins growing at a much faster rate, to the point where it becomes a reliable food source for the colony.
There are roughly twice as many fungus-farming termites as there are ants, and their methods of production are arguably even more gross. The workers will eat decaying plant material, excrete it, and use the resulting fecal pellets to create a ‘fungus comb’, which fungal spores (often from Termitomyces) are deposited onto. Like ants, they’ll constantly tend to these ‘fungus combs’, relying on them as a main source of food.
Scuba gear
The diving bell spider (Argyroneta aquatica), like all spiders, needs to breathe air, yet it spends almost its entire life underwater. To maintain its fully aquatic lifestyle while avoiding drowning, the spider creates its own diving bell - hence its name.
Before the days of scuba equipment, divers relied on these open-bottomed chambers as temporary stores of air while underwater, copying - perhaps unknowingly - a spider that had mastered the craft long prior.
To create its underwater masterpiece, a diving bell spider starts by weaving a dome-shaped web between underwater plants. Next, it rises to the water’s surface, trapping tiny air bubbles against its hairy body.
It then carries these to its web and releases them, filling it with air. In just a few trips, the spider will have built a bubble large enough for itself to fit inside. As well as serving as the spider’s own personal piece of atmosphere, the bubble is its home, not to mention a nursery for its eggs, if it’s a female.
These spiders needn’t worry about their bubbles running out of breathable oxygen. As there’s typically more oxygen in the surrounding water than the air within the bubble, it will gradually diffuse in, maintaining constant levels.
Art galleries
It’s not just us who like to impress our partners by presenting them with bouquets of flowers, bowerbirds do too, and they one up us by creating elaborate, twig-lined structures known as bowers that house their works of floral art.
As well as decorating their bowers with colourful flower petals, bowerbirds will also use shells, berries, and plastic waste in an attempt to woo potential mates. Some species, such as the satin bowerbird (Ptilonorhynchus violaceus) are even known to paint the walls of their bowers using a mixture of saliva and chewed-up plants, charcoal, or berries.
Only male bowerbirds build these ground-based structures, and they’re used strictly for courting females. After mating, females will build a comparatively simple, cup-shaped nest high up in the trees where they’ll eventually lay a clutch of one to three eggs. Like art critics, females aren’t taken by every bower they see. Some males don’t have an artistic eye and may go their entire lives without ever mating; other ‘master builders’ may mate with over 20 different females in a single season.
Silk scarecrows
Using silk, plant debris, and the rotting remains of their disembodied prey, the orb weaving spiders Cyclosa conica and Cyclosa longicauda create giant, spider-shaped scarecrows that sit on their webs and serve to frighten predators - and anyone reading about them. These grisly sculptors are very small, no more than half-a-centimetre in length, but their frankenstein-like creations can be several times their size.
In 2025, scientists closely examined the behaviours of these strange spiders and discovered some will actually conceal themselves inside their scarecrows, shaking their abdomens and creating vibrations that make the fake spiders seem as though they’re alive.
The scientists involved in this recent study believe the scarecrows have other functions too, such as serving as a safe place for the spiders to lay their eggs, as well as strengthening their webs against adverse weather. The scarecrows may also help them to catch prey by diverting attention away from themselves.
Homemade armour
Many animals have evolution to thank for their armour, but some aren’t so lucky - in several cases, the price of progress has been the loss of their main form of protection. Take octopuses for example, these squishy creatures evolved from hard-shelled ancestors some time during the age of the dinosaurs. Their lack of armour makes octopuses incredibly vulnerable to predators, though they’re not completely defenceless.
Many animals have evolution to thank for their armour, but some aren’t so lucky - in several cases, the price of progress has been the loss of their main form of protection. Take octopuses for example, these squishy creatures evolved from hard-shelled ancestors some time during the age of the dinosaurs. Their lack of armour makes octopuses incredibly vulnerable to predators, though they’re not completely defenceless.
In place of hard-shelled armour, evolution has bestowed intelligence on octopuses. The veined octopus (Amphioctopus marginatus) is a particularly brainy species, known to gather, stack, and carry discarded coconut shells to use as a portable shelter against predators.
The common blanket octopus (Tremoctopus violaceus) is also known to use tools, though on offense rather than defense. Some individuals have been observed wielding stinging tentacles from Portuguese Man O’Wars as weapons.
You don’t necessarily need brains to be an armourer, as caddisfly larvae demonstrate. Shortly after they hatch, these aquatic larvae will gather gravel, sand, twigs, and other debris and use it to make protective casings around themselves.
Dams visible from space
The architectural talents of beavers are well known, but did you know these busy rodents are capable of building dams visible from space? In 2007, a passing satellite spotted a giant, 800m-long structure in Canada’s Wood Buffalo National Park. This structure is as wide as the Burj Khalifa is tall, and further satellite images provided by NASA have revealed it to be up to 45 years old.
The dam holds back a growing, 17-acre lake that is believed to contain 70,000 cubic metres of water. Not much is known about the beavers who built this giant dam, but using satellite images (since the site is so remote), researchers have worked out there are at least two lodges, separated by around 300m. The latest satellite images show that new dams are being built and that the length of the dam could increase by up to 100m over the next decade.
In 2025, a different group of beavers living in the Czech Republic constructed a series of dams that, unknowing to them, accomplished a number of environmental goals set by the Czech government. This furry favour saved taxpayers approximately 25 million Czech Koruna, or £900,000!
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Makeshift ‘living’ rafts
There are many ways to make a raft, but there’s no way we’d ever take inspiration in this area from fire ants (Solenopsis invicta). This innovative species is known to construct makeshift rafts out of their own bodies during times of flood. To do so, workers will come together and interlock their legs and jaws, creating a stable structure that the colony’s queen and her larvae sit at the centre of.
Thanks to tiny, hydrophobic hairs all over the ants’ bodies, they’re able to repel water and keep their ‘living’ raft afloat.
These rafts are so buoyant that when researchers have tried to sink them with sticks they’ve refused to do so. As many as 100,000 individuals can make up a single raft, which - according to reports - can remain afloat for several weeks, perhaps even longer than a month.
These rafts may save a colony from drowning inside its underground nest, but it does introduce the ants to a new threat - hungry fish.
Slimy transport networks
They might not be an animal - nor a fungus, as is often thought - but this list wouldn’t be complete without a mention of slime moulds, particularly the bright-yellow variety known as Physarum polycephalum. This brainless microorganism is able to escape from traps, find its way around mazes, and even create elaborate transport networks that are more efficient than our own - which perhaps isn’t so shocking, depending on where you live.
In the early stages of its life cycle, P.polycephalum is a single-celled organism. However, as it grows it’s able to merge with others surrounding it, forming a larger organism that’s able to send out branches in search of food, such as fungal spores and bacteria. These branches can grow up to one metre in length and, according to researchers, have some form of primitive memory.
In 2010, researchers from Japan’s University of Hokkaido set up an experiment where they placed porridge oats inside a petri dish containing P.polycephalum. These porridge oats represented railway stations and they were placed in a configuration that mirrored those around Tokyo. The sample of P.polycephalum was left to do its thing and soon after it had created a copy of the Tokyo railway system, complete with all its branching routes. Since then, slime moulds have mapped optimum transport networks for several cities, as well as a worldwide trade network.
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