Do box jellyfish sleep at night?

Abstract

[Extract] A novel tagging technique has uncovered some surprising information about jellyfish behaviour. If you spend any time at all in tropical Australia, especially in the water, you will know about box jellyfish. You will also know that they have a major effect on the way people use the water, that they are capable of killing humans within minutes, and that vinegar is the first aid treatment of choice. But did you know that they sleep? We certainly didn't! About 12 months ago, we came up with a novel idea to try to track box jellyfish (Chironex fleckeri) using small ultrasonic transmitters (about 4 cm long and 12 mm in diameter). Using these for tracking marine animals is not new, but tracking jellyfish with them — that's certainly never been done before.