Rat Mojo All in the Tail

May 20, 2008 -- The function of tails has somewhat stumped scientists over the years, but now researchers have determined that female rats' tails play a very important role in the rodent mating process.

Female rats use their tails to direct, stimulate and balance their male partners, scientists determined.

Tails have been known to provide animals with extra sensory perception, since a tail can "feel" around itself, and to help with heat regulation, balance and navigation.

According to the research team who worked on the project, the new findings, which add mating facilitation to the tail's known list of functions, could also apply to cattle, cats, dogs, rabbits and certain primates, such as the spider monkey.

Every part of the tail appears to be important.

Pablo Pacheco, who led the study, told Discovery News that "the base of the female's tail facilitates, modulates and even permits the male's lateral mounting, which guarantees that the penile tip will find the vaginal opening," while the tip of her tail then offers the male stimulation.

Pacheco, a researcher at the Institute of Neuroethology at the University of Veracruz and the Institute of Biomedical Investigations at the National Autonomous University of Mexico, and his colleagues surgically removed both female and male rat tails and then observed how the removals affected their mating.

Normally males sniff out receptive females, produce ultrasonic mating calls and engage in urine marking. They then join the female and initiate rhythmic pelvic thrusts, which lead to the actual mating.

Neither the males nor the females found the tail-less subjects to be any less attractive. Males without tails seemed to move a bit awkwardly, but it was the tail-less females that really threw off the normal pattern, according to the study, which was published in the journal Animal Behavior.