Discovered in the deep: is this the world’s longest animal?
In 2020, about 600 metres (2,000ft) down in an underwater canyon off the coast of Western Australia, scientists encountered a long gelatinous creature suspended in a giant spiral. “It was like a rope on the horizon. You couldn’t miss it,” says Nerida Wilson from the Western Australian Museum. “It was so huge.”
It was a deep-sea siphonophore, a relative of the portuguese man o’ war, or blue bottles, that bob like party balloons on the sea surface, trailing deadly tentacles through the water. This one was probably a new species from the genus Apolemia, a group that generally look like tangled feather boas.
The spiral arrangement is known to be a feeding posture in these types of siphonophores. Numerous stinging tentacles create a wall of death in the water, trapping small prey, including crustaceans and fish.
Finding it was one of the chance encounters that are common in deepsea research. The scientists’ aim was to study life on the deep seabed, and they just happened to come across this floating jelly while their submersible was on its two-hour transit back to the ship, the research vessel Falkor, then run by the Schmidt Ocean Institute.
Screens in different parts of the Falkor were transmitting live footage from the submersible. Wilson describes how everyone onboard was simultaneously mesmerised and puzzled when the enormous spiral came into view. They all swarmed into the control room to get a better look. “It was such a beautiful energy,” says Wilson. “Everyone was like, ‘What is this?’”
Time was already short because the dive had run over schedule, and so the submersible pilot, controlling it from the surface, could only spend a few moments with the animal. “We circled around, took some footage and a little sample of tissue,” Wilson says. “Then we just had to go on our merry way.”
Siphonophores look like jellyfish, and they do belong to the same group of animals, but they build their bodies in a unique way – more like hundreds of tiny jellyfish stuck together. Yet, a siphonophore is a single organism. “It did have two parents,” says Wilson. “It