In the morning, we found a group of Bottlenose dolphins (Tursiops truncatus) rushing through the waves, lifting their large heads out of the water. Our afternoon tours were astonished by the acrobatic leaps of the slender Striped dolphins (Stenella coeruleoalba). It seemed like a contest happening in the ocean, who would jump higher? Different to some of our guests’ hopes and expectations, not every whale and dolphin leaps in the same way and frequency. There exist hypotheses about the length to bodyweight ratio impeding some whales to jump – and still, I have heard stories and seen trustworthy friends’ images of Fin whales lifting their body almost completely out of the water – they might just wanted to prove science and gravity wrong? Anyway, it seems reasonable that a slender, average weighting 100-150 kg Striped dolphin jumps out more often than a bulky Bottlenose dolphin with weights of up to 650 kg. But weight alone is not the answer – there are just some species that jump much more frequently than others. Now, the obvious question is – Why do whales and dolphins jump? There are numerous speculations and interpretations from scientists, and I am sure the answer depends on the situation: Cetaceans communicate over sounds, and a breach onto the ocean surface does make a loud noise. It could be a warning, aggressive or playful communication. Often we observe dolphins jumping in the weirdest way, trying to shake off unwanted remora fish or other parasites. In the case of our Striped dolphins, they often porpoise – they jump in a line out of the water – taking advantage of the fact that density in the air is less than in the water. They manage to travel faster that way while catching a breath. Pretty clever, don’t you think? We might never read our dolphins’ minds and know the exact reason why, but we’ll always appreciate when they do decide to be acrobatic!
By Sarah Kather
Sightings of the day
Ribeira Brava
09:30 No sightings
13:30 Striped dolphins
Stenella
09:30 Bottlenose dolphins
13:30 Striped dolphins