Trick or Treat!

Halloween is the perfect time for disguises and humans typically have lots of fun dressing up in amusing costumes, pretending to be something they’re not. But in the aquatic world, however, deception is an altogether more serious business and the stakes are far higher. The power of disguise can mean the difference between life and death for both predators and their prey, so nature is full of tricksters whose survival depends on their ability to outwit their opponents.

For example, the Bluestreak Cleaner (Labroides dimidiatus) is a harmless and helpful cleaner wrasse that posts itself at “cleaning stations” around coral reefs, removing parasites and detritus from other fish. The arrangement works well for both parties as the cleaners have their meals brought right to their door whilst their “clients” rid themselves of annoying parasites. However, the False Cleanerfish (Aspidontus taeniatus) has craftily figured out a way to take advantage of this.

Exhibiting a type of behaviour known as “aggressive mimicry” it disguises itself as an adult Bluestreak Cleaner Wrasse, and instead of removing parasites from client fish as a normal cleaner would do, the impostor removes a bite of flesh. Since they are ‘disguised’ as cleaner fish, they are able to trick their prey into coming right over to them before launching their “trick or treat” attacks. However, as with any kind of trickery, moderation is key, and once there are too many mimics around, their would-be targets become far more wary.