Swarms of the hyperiid amphipod Themisto gaudichaudii along the False Bay (Western Cape, South Africa) coastline

Tornado-shaped swarms of the hyperiid amphipod Themisto gaudichaudii were observed along the coast of False Bay, South Africa. This is the first time such swarming behaviour has been recorded in the area. The swarms were confirmed to be monospecific, with the majority of the individuals being female. At least 26% of females were gravid and there was no statistical difference in size among males, gravid females, and non-gravid females.