A recent scientific publication in Aquatic Mammals shared the first detection of polymastia in the Mediterranean monk seal.
The Mediterranean monk seal is one of the rarest mammals worldwide, even more endangered than the Hawaiian monk seal. Both belong to the family of Phocidae, also known as earless or true seals. But both species differ from other members of this family in that they have four nipples, instead of two. Typically, the nipples are arranged two on each side of the belly with the navel in the center. Similar to the layout of dots on a domino symbolizing the number five.
Extra mammary glands is a condition known as polymastia.
The paper reported the first two known cases of polymastia in Mediterranean monk seals. And it happened, pretty much, by accident.
Lead author on the paper Miguel Ángel Cedenilla says, the detection of the first case was pure serendipity. In a Facebook post, he’s quoted as saying, “In November 2016, while trying to tag a female on Deserta Grande Island with a Fastloc GPS, in full development of the LIFE MADEIRA MONK SEAL project, we realized something strange. Of the four females that had given birth, one had lost her calf. But she acted as a foster mother to the other pups. Our surprise was to see that three jets of milk from three well-separated points emanated from her belly. Clearly, that female had 3 active teats on her right flank. It was Rosa Pires who came up with the most appropriate name possible to call this new female: ‘Maminhas.’ which in Portuguese means ‘mamas.’”
All total, this Mediterranean monk seal had five nipples.
Then, in March 2020, another Mediterranean with polymastia was discovered.
According to the paper, “The second case was observed at the Cabo Blanco monk seal colony (Western Sahara/ Mauritania) through photo-identification pictures taken of breeding female 2363, “Oca,” in March 2020. Although monitored since 2011, and having had at least three pups in 2012, 2014, and 2020, no lactation of this female had been recorded, and it was not possible to know if the 5th nipple was active in milk production.”
There happens to be a Hawaiian monk seal well-known around Kauai’ as “Triple Nipple.” As the nickname implies, she has three nipples. Not that she has a bonus nipple and, hence, a total of five. She has a total of three nipples, instead of the more common four. Her scientific ID is RK14; however, she’s currently untagged, so the best way to ID her is by the presence of her three nipples.
PC: Aquatic Mammals Journal
Kaua'i Seals 