Mimics don’t fool each other (much)!

Ants are highly aggressive, and many species like to avoid them. Some animals make use of this fact, by trying to look like an ant to make sure predators will avoid them.

Take for example this Sphecotypus spider.

Sphecotypus spider

Sphecotypus spider. Picture by Alex Wild.

As you can see, it imitates Pachycondyla ants almost perfectly.

The Pachychondyla ant which is the model for the spider to mimic

The Pachychondyla ant which the spider tries to mimic. Picture by Alex Wild.

When you’re a mimic, one problem arises however: how does one recognize possible sexual partners? Partners will look like ants…and if there’s one thing you should avoid…it’s ants (as they will eat you)! However, by looking like ants they manage to avoid being eaten by predators. Dilemma!

Two researchers from the University of New Zealand were very interested in how these ant-mimicking spiders solve this problem. They tested the vision of male spiders, by putting either a common housefly (which is prey for the spider), a ‘normal’ ant, an ant which is the species that the spider is trying to mimic, or a female spider in a glass vial. Afterwards they allowed the male to look at these vials, and the researchers recorded the displaying behavior of the male.

The male responded about 6 times more to the spider female than to ants, and did not display at all to the fly. This means that the males are very well able to recognize their sexual partners, but are not able to do this perfectly, and might sometimes make a mistake.

So while looking like an ant has big benefits (not being eaten is pretty nice), it might have a slight drawback, as males might sometimes come too close to real ants (thinking they are female spiders) and be attacked in the process.

Source:
Nelson XJ & Jackson RR (2007). Vision-based ability of an ant-mimicking jumping spider to discriminate between models, conspecific individuals and prey. Insectes Sociaux 54: 1-4

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