06.11.2018 – Honest signals

The Atlantic ocean had quite a bit of entertainment in store for us today. On both tours we were able to see Short-finned pilot whales (Globicephala macrorhynchus) and Sperm whales (Physeter macrocephalus). While the Pilot whales were travelling in their usual lethargic manner, one of the Sperm whales gave our guests an absolute show on both tours. The animal breached over the high swell and also slapped its enormous fluke at the waters surface several times, in a repetitive behaviour known as lobtailing or tail-slapping. Of course we cannot be entirely sure that it was indeed the same animal on all occasions but it is highly likely as individuals usually breach several times in a row.

Lobtailing and breaching are two types of surface behaviours that are exhibited by almost all cetaceans. Breaching itself is defined as an intentional surfacing behavior from a cetacean during which the animal lunges out of the water, exposing at least 40% of its body. The reasons for breaching amongst cetaceans has long been discussed amongst scientists but experts largely support the theory of „honest signalling“, where the animal uses nonverbal signals to communicate with other group members. While lobtailing is generally used to communicate with peers at close range, a breach is very loud and can be used as a signal in long-distance communication.

Sperm whale groups are generally dispersed over a large area as many of the animals dive individually to forage in the depths. Younger animals, like the juvenile that was observed today, are not able to dive to the same depths and for the same amount of time as the adults of the herd and often remain logging at the surface. The breaching animal today was most likely a juvenile and, while one may interpret its behaviour as playful or a way of dislodging parasites, it may very well be that it was summoning the older animals to its side. Surely enough, the larger animals showed up after the repetitive tail slaps and breaches. Of course this is merely a theory; the actual reason behind breaching remains unclear and depends on the situation and personality of the animal. What scientists have established is that it occurs more frequently with animals that occur in larger social groups, like most toothed whales.

Either way the sighting was spectacular and the afternoon tour left two of our younger guests on board, Rohan and Harres, so thrilled that they left us a little surprise artwork the following morning which is already decorating our „wall of fame“ in the office! Thank you very much boys, we hope to welcome you on board again soon!

By Paula Thake

Sightings of the day

Stenella

10:00 Short-finned pilot whales, Sperm whales

15:00 Short-finned pilot whales, Sperm whales