A few studies have suggested that prostitution exists among different species of animals such as Adélie penguins. The concept is also known as transactional sex.
Penguins use stones for building their nests. Based on a 1998 study, media reports stated that a shortage of stones led female Adélie penguins to trade sex for stones.
Prostitution in animals was first reported in 1998 by Fiona Hunter, a researcher at the University of Cambridge, and Lloyd Davis of the University of Otago, who had spent five years observing the mating behavior of Adélie penguins. The study was conducted as part of an Antarctica New Zealand programme on the Ross Island, approximately 800 miles (1,300 km) from the South Pole.
According to the report about the study published by BBC News Online, some female penguins sneak around on their partners. These prostitutes have sex with unattached males and take a pebble from the male's nest after having sex
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