07.06.2019 – “Water telegram”

Today our sightings were under the motto “like on a band-conveyor”. A good two nautical miles from the coast, we hardly needed to do anything else than to wait. The Bottlenose dolphins (Tursiops truncatus) as well as the Pilot whales (Globicephala macrorhynchus) were distributed over large areas. The grey dolphins were our first discovery but soon we saw as well the typical round curved fins of Pilot whales. Again and again from behind, animals pulled past us. Actually, this was a permanent sighting churning. In the big picture it turned out that the Bottlenose dolphins travelled in the majority in front of the Pilot whales to the south-east.

A Pilot whale repeatedly hit the surface with his head and forefront of it‘s body. A very interesting observation! Such behavior is for communication. In this case, our guests could also watch closely what happened. A sub-group that passed by our boat stopped and drifted beside us until the communicating animal had joined them. Only then did everyone move together away from us. This pilot whale, who was slightly behind the others, asked his conspecifics to wait, as it were, via a “water telegram” (a clapping sound on the sea surface).

Sound moves under water five times faster than in the air. Amazing when you consider that the frictional resistance of the water is many times higher than the air resistance. Why is it that the sound moves faster in the wet blue? Exactly for the same reason that it is harder to move in the water faster than on land. The greater density is the puzzle solution! The speed of sound under water is at a water temperature of 20C at 1500m per second!! On land, the same sound would travel only 343 meters per second at an outside temperature of 20C. The speed of sound even increases with increased temperature, pressure and salt content. Since dolphins can virtually “see” with their ears and use their sound to recognize the situation, one can say: Dolphins hear three-dimensionally!

Once again a special thank you to our interested guests on today’s Ribeira Brava tour and a thank you for the wonderful conversation about our wondrous and wonderful nature. I always get the heart up!

By Fatima Kutzschbach

Sightings of the day

Ribeira Brava

09:00 Bottlenose dolphins, Pilot whales

Stenella

18:00 Common dolphins