04.12.2018 – Venus & Mars

What a show! The lucky guests aboard our traditional boat were granted a spectacular Sperm whale (Physeter macrocephalus) sighting this morning, with two animals breaching several times, making many of our guests exclaim in awe and happiness. The group was very dispersed and one theory as to why these enormous cetaceans lunge out of the water is to summon the rest of their pod. I was then asked whether Sperm whales always occur in groups and, despite them being the largest members of the notoriously social toothed whale family (Odontoceti), the answer is no.

While females spend their entire lives in the stable matrilineal pod they were born into and remain in low latitudes all year round, males have a very different latitudinal distribution and social structure. In the northern hemisphere, sexually mature males leave their maternal group to travel northwards alongside other juvenile males to feed in productive multi-layered foraging grounds. At the age of approximately 27 years, the adult bulls then return to breeding grounds to mate with females from different pods, keeping the gene pool healthy and diverse. The range of these multilatitudinal long-distance migrations tend to increase with age, along with the animals solitude. In summer we often encounter these enormous loners and these are often the animals that enjoy engaging in the impressive breaches we witnessed today.

Male and female sperm whales don’t only differ in their lifestyles; the species also displays the highest degree of sexual dimorphism in the toothed whale family. While females tend to reach lengths of 12-13m and weigh around 20 tons on average, large bulls can be up to 20m long and reach masses of a whopping 40 tons! So if we encounter a Sperm whale whose length exceeds that of our traditional boat, we can be pretty sure that it’s a bull.

The phrase „girls are from venus and men are from mars“ can therefore also be applied to the incredibly different male and female Sperm whales. This sexual dimorphism undoubtedly makes these animals all the more mysterious and interesting.

By Paula Thake

Sightings of the day

Ribeira Brava

10:00 Sperm whales