A spider has been walking through Liverpool and people have been making great allowances for it because of its size. It was made in Nantes and brought to Merseyside by ship and reassembled there, and during the night it was suspended from the side of a tower block to greet commuters on their way to work. “I wouldn’t like to meet it in the dark”, an onlooker said. “They say it’s going to walk the streets but I hope I’m not down here when it does.”

Twelve puppeteers sit aboard the spider to operate the levers and pedals it uses to control its movements. It moves carefully and with purposeful grace, and had prepared slow performances to deliver through the course of its stay.

This week I visited the workshop of the people who’d made the spider, where you can go for walks aboard their elephant. They are gradually building a very large merry-go-round made of sea and air creatures which will each be individually controllable by the people riding them. Some are for children and some for adults. In the workshop I saw three people sitting in small metal seats built into the back of a blue crab, learning to control the sideways movements of its legs and pincers using levers and pedals.

The seats face inwards so the three operators can keep an eye on one another’s actions. The pedals and levers are positioned in such a way as to constrain the puppeteers to move their limbs in sympathy with the animal, with arms coinciding and crossing in the air in repeated jolts and curves, and knees and elbows opening and closing sideways and contradictorily. The available repertoire of human gestures for the crab’s operation must have been choreographed into the design of the crab’s form and movement, to extend the slow and deliberate dance of the crustacean into the care of the performers.

And because the puppeteers I was watching had only just begun to learn the machine, the bumpiness of their movements – their mistakes and hasty glances down and back as arms collide and pedals clash and something knocked something else, or banged against the floor, or jarred with another limb – all fed into the crab so it jolted and stirred in vigorous agreement. The apparatus seemed to extend out both ways from the shell, so that the machine and the people were all puppeteers, all conducting one another at once.