Sperm whales – in the dark blue of the sea

Excerpt from our chapter: Love and sex

Sexual maturity

Last year, for example, we observed a large adult male sperm whale that had only arrived a few days ago and had not yet joined any companions. During the morning we saw him jump out of the water twice, which seemed very impressive given his size. In the afternoon we found our big, strong, lonely sperm whale not so lonely anymore. He had gathered a proud group of 11 sperm whales around him. Including many females, some young sperm whales and also a baby. At approximately 17 meters, it was by far the most impressive sperm whale in this family. Did he attract the attention of the other whales with his jumps in the morning? Did he perhaps even call them together? The fact is that we saw him swimming alone days before and in the morning, but after the jumps he had a whole family gathered around him.

Of course, he was only interested in females that were ready to mate, because that was the reason for his long journey from the Arctic here to Dominica. He wants to mate, but this isn't very easy with a full-grown bull of his size.

In male sperm whales, puberty begins at an average age of 9 years, when they have reached a size of 9 - 10 meters. However, spermatogenesis, or sexual maturity, is not completed until the child is around 20 years old.

However, sexual maturity in female sperm whales begins much earlier. With an average age of 9 years and a height of 9 meters, they are already taking part in reproduction. Sexually mature females usually ovulate in spring (January to July). Off the Azores, for example, the peak of mating has been observed between March and May.

Sexual organs

Penis eines Pottwals unter Wasser © Steffen

As in reptiles, the testicles are located behind the kidneys above the bladder. They are embedded in a thick scrotum with many blood vessels running through it and are sufficiently cooled with strongly cooled venous blood from the fluke. During sexual maturity, the size of the testicles increases significantly.

The penis of a sexually mature bull sperm whale is up to two meters long. It is anchored to the pelvic bone and lies in an S-shape within the abdominal cavity when at rest. The front part of the penis, surrounded by a strongly folded foreskin, lies in the penile pouch, which is closed to the outside with a narrow, elongated slit, the so-called genital slit. As a result, during an erection, the straightened penis is turned outward, which can be pulled back into the abdominal cavity with the help of a powerful retractor muscle.

Penis eines gestrandeten Pottwals  © Steffen

Hoden eines Pottwals © Steffen

Weibliche Organe eines Wals © Behrmann

The size of the testicles is also important in other whale species. In males that fight for a particular female and drive their rivals away, such as humpback whales, the testicles are relatively small. In males, which mate with many females as often as possible and do not hinder their rivals, as has been observed in right whales, the testicles are much larger.

The erectile tissue of the penis is surrounded by elastic and collagenous tissue, which is permeated by blood vessels and nerves and covered by a thick layer of muscle packages. Camels also have a comparable muscular penis. However, the corpora cavernosa portion of the relatively long and mobile penis is very small compared to other mammals.

The female sexual organs are typical of mammals. The ovaries are located in approximately the same place as the testicles in male animals. The uterus is comparable to those of carnivores and pigs, but develops slightly differently in toothed and baleen whales. In immature whales, the uterus still consists of two so-called uterine horns that are identically formed.

However, later in toothed whales the left uterine horn develops wider because that is where the fetus generally develops. In baleen whales, however, the fetus can develop in both uterine horns.

The fertilized egg implants very loosely in the mucous membrane and therefore has the advantage that there is only minimal bleeding after birth. The relatively long cervix has a thick, muscular wall and extends into the interior of the vagina. The vagina merges into an elongated fold (vulva) with two pairs of lips, which lies directly in front of the anus.

Breast milk

The two elongated mammary glands, which are up to 120 cm long, lie on either side of the vaginal cleft and, in a nursing mother, swell considerably so that they form a slight elevation that is visible from the outside. The two teats, which normally lie in two small slits, protrude during suckling. A contraction muscle enables the milk to be squirted out under pressure, because the young animals do not have movable lips and therefore cannot suckle themselves.
The mother's milk is injected into their mouths. While the baby holds the teats tightly closed, it repeatedly pushes against the muscles and thus activates the expulsion of milk. The harder he pumps, the more milk is injected into his mouth. Tightly enclosing the teats with the mouth also prevents salt water from being swallowed while suckling.

Whales' mother's milk consists of 40 - 50% fat (in contrast to land mammals with 2 - 17%). It has a high proportion of protein, phosphorus and calcium but less water and lactose (1-2%) than the milk of land mammals.

Milchdrüsen © Steffen

For example, the birth date of a pregnant dolphin can be predicted based on the distance between the suckling slits. In dolphins kept in dolphinariums, the distance between the nursing slits of pregnant females is measured daily shortly before birth. A distance of 40 mm is normal. But when birth is imminent, the distance is 60 mm. In addition to the body temperature dropping from the normal 98 - 99o Fahrenheit (36.7o - 37.2o Celsius) to 96o Fahrenheit (35.6o Celsius), these are sure signs that birth is imminent.


But how does an adult sperm whale bull, 18 - 20 meters long, manage to find the even further away vagina with his two meter long penis, which is about 10 - 12 meters away from his eyes, in order to mate? And all this without hands?

As already described above, the whale's penis is moved with the help of many muscles. This explains its movements, but not how these movements are coordinated.

In 1994, Günther Behrmann wrote an extremely interesting paper on the “movement coordination of the penis during copulation”. For this purpose, he examined porpoises and his results were unique.

The tip of the penis no longer contains any muscles and the erectile tissue is only surrounded by connective tissue, which has a much stronger blood supply. This connective tissue contains many nerve endings, such as those found in the tip of the nose of toothed whales or the fingertips of humans.

The skin of the tip of the penis is only 0.5 – 1 mm thick, connected like a nail to the underlying tissue layer and covered by a mucous membrane. So far everything is comparable to other mammals. However, during his investigations, Günther Behrmann came across previously undiscovered sensory hairs that cover the tip of the penis (glans) like fur. There are around 150 such sensory hairs per square millimeter. At the center of each sensory hair is a tube that can be viewed as a supply channel. Each sensory hair contains approximately 2,500 chemoreceptors measuring up to a thousandth of a millimeter in size. These can now detect the scents emanating from the vagina. The whale penis is therefore actively controlled by these chemoreceptors and thus finds its way to the vagina.

This method is unique in the animal kingdom.

Penisspitze eines Pottwals © Steffen

After successful reproduction, the young are born after a gestation period of approximately 15 months. Sperm whales usually only give birth to a single calf every four to six years. If you now consider that only 10-15% of sexually mature males participate in reproduction and because of the long gestation and breastfeeding period only about 35% of sexually mature female sperm whales are ready to mate, the pregnancy rate is the lowest in the entire animal kingdom.

The hunting of sperm whales actually has a significant negative impact. After 15 months a single calf is born and after at least 3 - 4 years the mother would give birth again. Today it only takes humans 20 minutes to kill a single sperm whale. Of course, this is only for scientific purposes.

This method is unique to us humans.

Über uns


  • Pottwale - Im dunklen Blau des Meeres
  • Wale Hautnah - Das Buch
  • leider ausverkauft und vergriffen!