Archive for November, 2022

Monk Seal Monday #177: Triple Nipple

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.

Female Mediterranean monk seal on side with three nipples exposed and streaming milk.
Nursing Mediterranean monk seal.

PC: Aquatic Mammals Journal

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Monk Seal Monday #176: Molting

Right now, there’s a very visible monk seal hanging out at Poipu. He’s been there for a week, seemingly day and night. This is very natural. Approximately, once a year, Hawaiian monk seals go through a “catastrophic molt,” meaning they lose the top layer of skin and fur in one concentrated period of time, rather than continually throughout the year. The seal at Poipu is an untagged male (with a temp ID of V3) whose molt is about 70% complete. The molting process can take one to two weeks.

Because molting requires great energetic resources, during this time, the seal will usually stick pretty close to the beach, often spending the night tucked high up the beach and under bushes.

Molting is a vulnerable time for monk seals, another reason to encourage folks to keep dogs on leashes. Typically, the molt starts on the belly, flippers, muzzle, and scars. Then, moves to the back. The molting pattern isn’t exactly “attractive.” A seal with patches of dead skin falling off can often cause beach-goers concern, thinking the seal is sick or, even, dead. Adult females will often molt soon after they wean their pups.

Basically, seals molt, because their coat gets dirty. After spending long bouts of time at sea, algae will often grow on their fur. If you see a seemingly green-colored seal, you’ll know he or she is nearing his/her molt.

After molting, monk seals regain their dark gray to brown color on their dorsal (back) side and a light gray to yellowish brown color on their under (ventral) side. This difference in coloration is known as “countershading.” From below, the seal’s light belly blends in with the sunny surface of the ocean. From above, the seal’s darker back is closer in color to the dark ocean floor. This serves as camouflage for seals. It helps them sneak up on prey, as well as, hide from sharks and other predators.

Here’s a series of photos from a few years ago that show the molting progression.

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Stories related to this research:

Motherload: The Story of a Fertile Turtle in the Hawaiian Islands

A Continuation of Motherload: The Story of a Fertile Turtle in the Hawaiian Islands

Punahele: A Green Sea Turtle’s Journey to “Destination Unknown”

Destination Known: Punahele’s Safe Return Home from Lalo

Turtle and Seal Biologists Deploy to Papahānaumokuākea for the 2022 Field Season

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Field Report: October 2022

Monthly Update: The Kauai team logged 277 seal sightings this month. This included 32 individually identified seals.

  • October: 277
  • September: 400
  • August: 320
  • July: 311
  • June: 283
  • May: 248
  • April: 294
  • March: 292
  • February: 233
  • January: 233
  • December: 267
  • November: 168
  • October: 229


·       Five large dogs harassed and possibly bit an adult seal at Makua at Cannon’s surf break (near Tunnels surf break). It appeared one man brought all 5 dogs to the beach and allowed them to run off leash and did very little to stop them from harassing and chasing the seal off the beach. Photos were submitted of the dogs and owner, and sent to DOCARE and Humane Society for further action. All seals seen in the area since are in good health and show no signs of dog bite injuries.


·       Continue to closely monitor yearling RP32 who is in thin body condition. The seal is likely in pre-molt.

·       PK3 weaned from mother RK28 after 40 days of nursing. The pup was flipper tagged with Q78 and Q79 tags and vaccinated. His new ID is RQ78. The pup has remained in his natal area and is thriving.

Molting: 5 seals molted this past month.

Vaccination: Vaccinated weaned pup RQ78.

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