When filmmakers slipped a robot crab into a real crab aggregation, they expected curiosity. What they captured instead was a startling display of cooperation and vulnerability that one voice on the soundtrack summed up with a warning: “It’s not over yet.” The mechanical intruder did not just survive among the claws, it became a focal point for a drama about survival, risk and the hidden social lives of sea creatures.
I watched the footage with the same mix of disbelief and recognition that has greeted earlier “spy creature” projects. The robot crab’s camera does more than deliver a clever gimmick. It reveals how animals respond when they sense both danger and opportunity, and how a swarm of crustaceans can behave less like a mindless crowd and more like a community under siege.
The spy crab and a sea of vulnerable shells
The robot crab belongs to a growing cast of lifelike cameras that have been deployed in projects such as Spy in the, designed to slip unnoticed into animal societies. In this case, the decoy was modelled on a spider crab and sent into a mass gathering of crabs that had converged in shallow water to shed their shells. The sequence is framed by the line “It’s not over yet,” a reminder that the real jeopardy begins once the old armour comes off and the animals are soft, slow and exposed.
For the BBC team behind the sequence, the goal was to see how crabs behave when thousands of them are simultaneously at risk. Filmmakers followed the moment when the crabs outgrowing their tough shells crowd together, creating a living carpet of legs and claws. The robot, disguised among them, records the instant when the first individuals crack open their exoskeletons and emerge soft and pale, a transformation that turns the seafloor into a buffet for any predator that dares to swoop in.
Predators, stingrays and an unlikely defender
The threat is not theoretical. In the same coastal shallows, a single stingray can turn a moulting ground into a killing field. One sequence describes a 4 meter stingray that can eat 50 crabs a day, hoovering up any that have lost their shell and cannot yet fight back. The robot crab’s camera shows how a shadow passing overhead can send a ripple of panic through the aggregation, with animals piling over one another in a frantic attempt to bury themselves or wedge under the nearest rock.
A separate Video Transcript of the same behaviour spells it out in blunt terms. “Four meter stingray can eat 50 crabs a day. They hoover up any who’ve lost their shell. Our spy becomes the crab’s defender.” Those lines, with their capitalised “Four”, “They” and “Our”, capture the pivot in the story. The robot, initially just an observer, ends up wedged between the predator and the soft-bodied crabs, its hard casing taking the brunt of the stingray’s probing as the living animals cluster behind it. The footage turns a piece of equipment into a kind of accidental shield, a reminder that technology can alter the very behaviour it is trying to document.
Mass gatherings and the power of numbers
What makes the robot crab sequence so striking is the scale of the crowd it infiltrates. Giant spider crabs are known to gather in their thousands in places like Port Phillip Bay near Melbourne, where divers have described the sight as “Massive” and “gobsmackingly amazing.” In those scenes, the seabed disappears under a shifting mound of legs as Giant Spider Crabs stack themselves several layers deep, a living barricade that confuses predators and provides at least some safety in numbers.
Scientists who study these events emphasise that the behaviour is not random. According to the Spider Crab Watch project, the shedding process is called moulting and, “Whilst the” crabs are waiting for their new shells to harden, they are soft and vulnerable. The animals respond by forming an aggregation to seek protection in numbers, a strategy that the robot crab’s camera captures from the inside. The footage shows individuals climbing over the mechanical intruder as if it were just another body in the pile, reinforcing the idea that the crowd itself is the defence.
Deep relationships on a crowded seabed
The robot crab sequence also plugs into a broader effort to document what producers call “deep relationships” in the ocean. In one related scene, a female crab makes it through the chaos and, as the narration puts it, “She’s made it. Now, to vanish among the masses.” In the sequence, the greater the numbers, the harder it is for the ray to pick off individuals, and those with hard shells form a kind of living rampart around the soft ones. At one point, crabs come to the spy itself, treating the robot as part of the protective landscape rather than an outsider.
That sense of connection is echoed in another description of the project, which notes that She has to disappear into the crowd to survive and that “Now” the mass of bodies becomes her only refuge. The robot crab’s vantage point makes those relationships visible, from the way individuals jostle for position to the moments when one crab appears to shelter another. It is a reminder that even in a crush of thousands, survival can hinge on tiny acts of positioning and cooperation that would be invisible without a camera hidden in plain sight.
From Christmas Island to living rooms worldwide
The crab spy is not confined to one coastline. A similar robotic crustacean has been filmed trundling across Christmas Island, where millions of red crabs migrate from forest to sea. In that video, narrated by David Tennant, the mechanical interloper navigates a river of scarlet bodies, its built-in camera capturing close-ups of claws, eyes and antennae that would be impossible with a diver’s rig. The Christmas Island sequence underlines how the same technology can reveal both mass movement on a landscape scale and intimate behaviour at ground level.
These projects sit within a wider family of productions that use animatronic “spy creatures” to record rarely seen animal behaviour. As one overview of the series notes, viewers can watch episodes on television and, After each broadcast, stream them online for a limited time. The same summary highlights that the spy creatures’ built in cameras are many, a design choice that lets editors cut from a wide shot of a crab swarm to an extreme close-up of a single eye in a fraction of a second. The result is a kind of immersive surveillance that, for once, is turned not on people but on the other species that share our planet.
More from Morning Overview