Do Cats Have Navels?

Everyone knows that male cats have nipples, don’t they? (if you ask me why, it’s just like your boyfriend also has nipples)? Hahaha….

Male cats also have nipples. Image source: Sohu

When I patted my cat recently, I suddenly found a funny thing, that is, cats also had navels! It is a pretty cute dot, right between two rows of nipples.

What are you looking at? Image source: cat-world

Strange knowledge is accruing. Let’s see what it is.

Navel? That’s a Scar!

It sounds strange that cats have navels. Anyway, their navels are not as evident as humans’.

It’s time to show your navel. Have you completed your weight loss “undertaking”? 

Image source: Sina

On second thought, however, it seems well-justified that cats have navels. After all, they are viviparous mammals, just like human beings.

For viviparous mammals, an umbilical cord plays a key role, by connecting fetus and placenta, constantly transporting water, nutrients and oxygen, etc. that the mother delivers to placenta to the fetus, and getting rid of metabolic waste generated by fetus.

An umbilical cord is a lifeline that connects fetus to mother. Image source: Kuaibao

Nevertheless, this lifeline is a temporary product that only works during the mother’s pregnancy. Once the fetus is born, it will fall out of use. 

For us humans, as soon as a baby is born, the doctor will cut the umbilical cord short and tie it up. If nothing goes wrong, the umbilical cord losing its function will dry up and fall off in a few days.

A red wound will be left when a navel just falls off. But don’t worry, it will heal in a few days. After that, due to the contraction of umbilical vessel in the body, the skin will be pulled inward and sunken, thus forming the familiar navel.

Therefore, in essence, a navel is a scar left after an umbilical cord falls off.

Cat: Why can’t I have a navel, for I am also viviparous?

Now that a navel is a scar left after an umbilical cord falls off, for creatures that rely on the umbilical cord to deliver nutrients to their fetuses, the umbilical cord will remain as a souvenir, and cats are among them.

So why do we seldom observe that cats have navels? It’s pretty easy to understand. Most cats are furry and wear “thick coats”, so their navels are often covered up. 

On the other hand, cats have different navels than ours. Our navels are inward-facing, clearly wrinkle, and hard to overlook, while the cats’ navels are much more “low-profile. They are generally smooth and round, with slight depression but not conspicuous. They can’t be felt at all across the thick fur.  

Many cat owners haven’t found that their cats have navels until the hair in their abdomens is shaved off when they are taken to a hospital for physical examination or treatment.

How many of you don’t know your cats have navels until you ask a doctor?

 Image source: I love Hami melon (Douban)

Of course, if you raise a dark cat (a cat whose skin is dark, not simply the fur), it is easy to find its navel. That is because the navel color of a dark-colored cat is easier to spot because it is slightly lighter than the skin, while the navel of a light-colored cat is easily confused with the skin, and hard to discern. 

So when is the best time to observe a cat’s navel? The answer is when the kitten was just born. After the kitten is born, the mother’s uterus contracts again and delivers the placenta, while the kitten is still attached to the placenta by the umbilical cord. Soon, the mother uses her sharp teeth to bite off the umbilical cord and eats the placenta. You can clearly see a small piece of umbilical cord attached to the kitten.  

The umbilical cord of a kitten. Image source: cat-world

The umbilical cord of a kitten. Image source: quora

Similar to human babies, in a few days, the umbilical cord of the kitten will shrink, fall off and leave a scar, that is, the kitten's navel.  

Apart from cats, cute little dogs around us also have navels. In reality, all mammals have navels. Even whales that settle in the sea are no exception. However, most animals’ navels will finally heal as small and inconspicuous scars. What’s more, many mammals wear thick fur coats, and one of the codes of conduct in the animal world is that they don’t readily expose their abdomens, so we can hardly notice their navels.

Only Mammals Have Navels? Wrong!

It is fair to say that the navel is one of the typical structures of mammals, but it is unnecessarily true to say that the navel is unique to mammals, for birds also have “navels”, too. 

Birds are not viviparous and don’t have a placental structure, so where do their “navels” come from? 

As we know, there is an important structure in the embryo of birds, which is called yolk. It is responsible for providing nutrients for developing embryos. The sac-like structure surrounding the yolk is the yolk sac, which secretes enzymes to degrade the yolk and generate soluble nutrients for use by the embryos. When nestlings break out of shells, a small amount of remaining yolk will be absorbed into the abdominal cavity together with the yolk sac, and become one of the nutrient sources for the initial growth and development of nestlings.

At this moment, very tiny scars (yolk sac scars) will be left on the nestlings, which typically heal and are almost invisible, so forget looking for birds’ “navels”. 

Strictly speaking, all amniotic animals (vertebrates that develop amniotic membrane structures during the development of embryo, including reptiles, birds and mammals) have similar structures (a structure that connects yolk or placenta to deliver nutrients to embryos), but the scars heal so much better in many animals than in mammals that they can’t be found at all. 

Be that as it may, whatever happens to other animals, at least your cats have navels, and the fun of patting cats will increase again.

Anyway, I’m gonna go home and battle with my cat master.