If You Could See What's Living on Your Skin, You'd Itch Too

The life in your belly button is not just fluff

The skin on your body is roughly two square meters in area or something equal to a ten foot long hallway carpet runner. And all of this carpet is the home of microscopic organisms, mostly bacteria, happily living and dying, some eating other bacteria, some waiting for the right conditions to over populate and cause itching and rashes or maybe hoping for a break in the skin to get inside and cause some real damage. Todar’s Online Textbook of Bacteriology indicates that we may have up to 200 species of bacteria on our skin with a total population of as many as  1012 (that's 1,ooo,ooo,ooo,ooo of these critters).

Your Body Is a Wonderland

Fortunately, most of these bacteria are harmless or may in fact be helping us by keeping pathogens from colonizing on our skin. Nonetheless, regular washing is important as a simple way of keeping our bacteriological skin "flora" in check. And just like we see different kinds of flora growing in marshes and deserts, different species of bacteria flourish on the moister parts of our body and those that are dryer.

Compounding this variation of habitat are tiny sebaceous glands which are found throughout our skin and secrete an oily, waxy material called sebum. Sebum helps to lubricate and waterproof the skin and hair so these glands are most prevalent on the face and scalp and absent from the palms of hands and soles of feet. Buildup of sebum can result in conditions like acne and cysts, but again, regular hygiene is usually sufficient to keep this buildup and the bacteria that live on it under control.Skin HabitatsCredit: NAtionaal Human Genome Research Institute

The "Habitats" of the Skin

While the habitats for bacteria on our skin can vary, the bacteria that will be present in each area are fairly predictable. The greatest variations from person to person are found in the potentially damp areas between the toes and fingers, in the armpits and in the navel cavity. It would seem that fingers and toes are most likely to be exposed to the greatest variety of external influences through handling things and walking on potentially nasty surfaces, armpits are influenced by high numbers of sweat glands and the navel is just an often forgotten part of the anatomy that seems to collect things that pass by.

Navel Study in North Carolina

The landscape of the navel is so variable and intriguing that a group of scientists at North Carolina State University and the North Carolina Museum of Natural Sciences initiated the Belly Button Biodiversity project.

By collecting cotton swab samples of the civilizations within the navels of hundreds of volunteers and cultivating the collections on growing media, they were able to make some generalizations about what goes on in our navels: 

  • Staphylococcus epidermidis, the most common skin bacteria is also the most common organism in the belly button, although they were also able to regularly grow bright yellow colonies of Micrococcus luteus, and gooey globs of Pseudomonas.
  • Your belly button is a lint trap for fabric fibers from clothing as well as dead skin, fat, sweat and dust.
  • Not many people clean their belly buttons with soap.
  • 96% of their participants have "innies," making outies a fairly rare occurance.
  • It’s possible to have a navel melanoma. Watching the size and shape of any moles there is important.
  • And, referencing a somewhat related study of belly button preferences at the University of Missouri, the ideal shape of the female belly button is one with a "T- or vertically shaped umbilicus with superior hooding." Any degree of protrusion, a horizontal orientation or distorted shape was found to detract from overall belly button appearance.

The Ideal T Shaped Navel

The ideal "T" belly button. But who knows what lurks within?

The bottom line on epidermal bacteria: they’re everywhere and in greater quantities and varieties than you can imagine. Regular cleaning and drying is important for their management, especially if there is a wound or break in the skin. And don’t neglect your belly button, that intriguing but often forgotten abdominal indenture that can take on a life of its own.