Even sea creatures need pampering. Manta rays make regular visits to ‘cleaning stations’, where small fish rid the rays of skin parasites at the coral-reef equivalent of a day spa. Now it seems that rays can identify and remember spots where they have received quality cleaning.
Cleaning stations are often centred on corals inhabited by cleaner shrimp or fish. To understand how these stations influence rays’ movements, Asia Armstrong at the University of Queensland in St Lucia, Australia, and her colleagues tracked 34 reef manta rays (Mobula alfredi) off the coast of eastern Australia for about 1.5 years.
The highest density of rays was found at places where cleaning fish called blue-streak cleaner wrasses (Labroides dimidiatus) were most abundant. Rays typically visited cleaning stations during the day, when cleaner wrasses are most active, and favoured stations close to foraging regions.
Rays are thought to prefer stations that provide superior cleaning — where the cleaners don’t bite them, for example. The rays’ behaviour suggests that they have a mental map of spots that offer both high-quality cleaning and proximity to foraging grounds.