Dolphins belong to the order Cetacea, meaning they are marine mammals, not fish. Like all mammals, dolphins breathe air, are warm-blooded, and nurse their young with milk. The common curiosity regarding whether dolphins possess a belly button stems from this shared mammalian biology, drawing a comparison between the aquatic species and their terrestrial counterparts. Understanding the basic anatomy of these intelligent creatures helps explain the presence of this specific feature.
Why Dolphins Must Have One
Yes, dolphins are born with a belly button, a biological necessity shared by nearly all placental mammals. This feature exists because the developing dolphin calf relies on the placenta during its gestation period inside the mother’s womb. The placenta acts as a life-support system, facilitating the exchange of oxygen, nutrients, and waste products between the mother and the fetus. This connection is maintained by the umbilical cord, which bypasses the need for the unborn calf to breathe or feed. Every dolphin, whale, and porpoise must have an umbilicus during its development.
Formation of the Umbilical Scar
The dolphin’s belly button is not an indentation but a permanent mark known as the umbilical scar. At birth, the umbilical cord separates from the newborn calf and the mother’s placenta, often breaking naturally as the calf is born, typically tail-first. This separation is unlike the surgical cutting performed on human babies. Once the cord breaks, the remaining tissue on the calf’s abdomen naturally dries and heals quickly in the water. This rapid healing process is partly attributed to the dolphin’s ability to regenerate tissue and its specialized blubber layer. The point where the cord was once attached closes up, leaving behind a fibrous tissue scar that marks the location of the former connection.
What the Belly Button Looks Like
The physical appearance of a dolphin’s belly button is quite different from the “innie” or “outie” seen on humans. Instead of a deep depression, the dolphin’s umbilicus is a small, subtle, and smooth linear scar or slit. This streamlined shape is perfectly adapted to the dolphin’s body, helping to maintain its hydrodynamic efficiency in the water. This scar is located on the ventral side, or underside, of the dolphin’s torpedo-shaped body. Specifically, it is situated along the midline, positioned roughly between the two pectoral fins and the genital slit. Because the scar is small and blends seamlessly into the smooth, gray skin, it is often difficult to spot, especially as they mature and the scar fades slightly.