11.05.2023 – Our Stenellas 

We know so much about many different types of dolphins but the species belonging to the genus Stenella have to belong to some of the best studied of all. In the taxonomical hierarchy, a genus is the second lowest category after species and describes a group of animal that, genetically speaking, are extremely closely related. The genus consists of five species; the Pantropical spotted dolphin (Stenella attenuata), the Spinner dolphin (Stenella longirostris), the Clymene dolphin (Stenella clymene), the Striped dolphins (Stenella coeruleoalba) and the Atlantic spotted dolphins (Stenella frontalis). 

The latter two species both occur in Madeiras waters and, despite their close taxonomic relationship, are completely different in their appearance, their site fidelity in Madeira and their characteristic behaviour towards boats. Our guests got a taste of these differences on both our tours today. 

Striped dolphins are beautiful oceanic dolphins that travel in enormous pods out in the open ocean and typically sport a beautiful flank pattern with stripes trailing along either side of their bodies. Smaller subgroups often separate from the larger oceanic pods and enter the safety of Madeiras waters, often in the presence of tiny calves. The smaller size of the group and the fact that it contains younger animals could contribute to the usual evasive nature of these dolphins towards boats.

The Atlantic spotted dolphins are another story. These dolphins also arrive in large groups but these pods often remain intact, occasionally fragmenting into subgroups during the day. They are seasonal dolphins with a characteristic spot pattern that intensifies as the animals age. This attribute together with their extremely curious behaviour towards boats has made them incredibly important for scientists studying dolphin behaviour. 

Despite their differences both species have the characteristic narrow beak that grants the genus its name (from Greek Steno meaning narrow) and both breach and leap in the typical acrobatic nature of the Stenella dolphins. The differences between Madeiras Stenella simply highlights the diversity found in the dolphin family, even amongst those who are closely related!

By Paula Thake

Sightings of the day

Ribeira Brava

09:30 Atlantic spotted dolphins, Striped dolphins

Stenella

13:30 Atlantic spotted dolphins, Striped dolphins