03.10.2017 – For whales and dolphins the ocean is not blue
Since some days now, Madeira is blessed with a cloudless sky and a glorious blue ocean. So the colour blue surrounds us with all its nuances. Who would think, that there might be marine living beings which are not able to see this?
It was a quite surprising the press release of the german scienitific Max-Planck Society in 2001. There, experts came to the conclusion that two big groups of marine mammals would not be able seeing colours. The scientists called it paradoxical colour-blindness. Because whales and seals were missing a certain type of cells (blue sensitive photoreceptors or s-cones). They only have one type of photoreceptors (or cones), the green sensitive ones. But with just one photoceptor type (besides rod) in the retina of the eye, there is no differentiation possible. Crazy world. For being able to watch colours, our eye needs to have several cell-cones types. Humans and primates can see very well colours, because they have three different types of cones photoreceptors: blue, green and red cones.
In the dark blue of the sea around us, we were happy to observe Tropical Whales and three different species of dolphins. In the afternoon tour some of the baleen whales were in a fast rush, in order to feed. Also the Atlantic spotted dolphins were hungry and catching their part of the prey.
by Astrid Haas
Sightings of the day:
10.00: Tropical whales, Striped dolphins and Bottlenose dolphins
15.00: Tropical whales and Atlantic spotted dolphins