Let’s start with “leaping” and “breaching”. When large whales leap, it is termed breaching, when the smaller toothed whales leap, it is generally termed leaping. The breach of a large whale is one of the most powerful actions performed by any animal on the Planet. Breaching is a jump where at least 40% of a whale’s body leaves the water. Breaching sperm whales approach the surface vertically from depth. Other animals swimming in water less deep, like humpback whales, make a horizontal approach to the breach, gaining speed until, at the last moment, they raise their heads and flukes, pivoting on their flippers, converting horizontal momentum into vertical motion in the process, and thus rising through the surface.
To make a full breach, a humpback whale breaks the surface at about 28 km/hr (about 8 m/s), close to its maximum speed. After breaking the surface, whales have many styles of breaches. In the classic breach of a large whale the animal emerges from the water at about 20 to 30 degrees from the vertical, twisting so as to land on its back or side, having shown about 90% of its body above the surface at peak emergence. However, about 20% of the breaches of sperm and humpback whales are “belly flops,” with the animal landing ventrally. Breaches are often performed in series. Upon reentry, breaching whales produce large splashes, which can be visible at many kilometers.
Frame-by-frame analysis of high-speed photography shows that there are two splashes: one is created as the animal falls onto the water surface and initiates a crater of water underneath it, and the other is the secondary splash (and slap sound) produced as the crater collapses on itself, in an act of cavitation. Frequent breachers include humpback, right, and sperm whales. In contrast, balaenopterids (blue, fin, sei, Bryde’s, minke) and most beaked whales breach more rarely. However, bottlenose whales, breach quite often.
Breaching and leaping are mainly correlated to sociality. Animals found in larger groups, and for whom social structure seems more important, breach more frequently. In sperm whales, the gregarious females breach more often than the much larger, and more solitary, males. Calves of many species breach more frequently than adults. Moreover, in some species including humpback, right, and sperm whales, breaching is observed frequently when groups merge or split. Male humpback whales sometimes breach when they stop singing. Breaching often occurs with lobtailing or flipper slapping, with different animals performing different activities at the same time, or one animal switching between different activities.
Breaches by one animal may trigger breaches by neighbours. As well, breaching rates of large whales increase with wind speed; the sound of the breach may serve for better communication in all directions in a surface-noisy ocean. Just as in large whales breaching, to clear the water a dolphin needs to attain rapid forward speed, near the limit of its swimming capability. Reentering the water can be head-first (unlike in breaching large whales, where it is never head-first), creating minimal splash and noise. It can consist of a side, back, or belly splash, resulting in a welter of white water and foam and a considerable percussive (splash) noise in-air and underwater.
There are many variations of the dolphins’ leaps because this aerial behaviour has different functions. Spotted and striped dolphins are the champion high leapers: they leap up to 7 m high in the air. These leaps may be performed largely for socialisation and communication but they may also serve the function of seeing to greater distance by gaining height and noisy leaps also occur to frighten fish and prey them easier.
1st Photo: Leaping - Striped Dolphin (photo by Stefano Bellomo)
2nd Photo: Breaching - Sperm Whale (photo by Carmelo Fanizza)
Breaching and leaping are not the only form of aerial behaviour of cetaceans.
"Lunging" might be a low form of a breach and may indicate a form of alertness or sociality. Lunging is often seen when baleen whales are feeding at the surface, but lunging can also be a behaviour that is directed at another individual or individuals, and can signal aggression, for example when male Risso’s dolphins physically compete for mates.
"Porposing" is the way that fast swimmers as the striped dolphins swim rising above water and submerging really fast. This behaviour is mostly connected with feeding or when young individuals play chasing one each other or when an adult male chase a female.
"Spy-hopping" or “eye out” by whales and dolphins consists of the animal slowly lifting the head out of the water almost or fully vertical, usually just to the level of the flippers. At times, spy-hopping is attended by a slow rotation of the body, and it appears that the whale or dolphin may be surveying the air environment.
"Lobtailing" or "tail-slapping" consists of forcefully slapping the tail onto the surface, either venter or dorsum up. Lobtailing produces a loud sound in air, but it is not all that loud underwater, and not nearly as loud as many of the vocalizations made by whales and dolphins.
"Flipper-slapping" by whales and dolphins occurs, like lobtailing, with either venter or dorsum of the flipper striking the surface. It also produces a percussive sound in air, and a less loud one underwater.
1st Photo: Spy-hopping - Risso's Dolphin / 2nd Photo: Tale-slapping - Striped Dolphin
(Photo by Stefano Bellomo)
Active behaviours are associated with high levels of alertness or sociality. Especially percussive signals may have direct communication functions. More social species tend to breach more, suggesting a communicative function. What might the breacher be signaling?
Suggestions for large whales include aggression, annoyance (perhaps with a nearby vessel), courtship, or a display of strength by males by showing the extent of its physical prowess. For dolphins, leaps have mainly been considered signals concerning schooling. Leaps may be used to define the deployment of a school, to recruit dolphins to a cooperative feeding event, or as social facilitation that reaffirms social bonds. Breaching, leaping, lobtailing and flipper slapping may help cetaceans feed by scaring, shocking or trapping their preys.
Another benefit of breaching and leaping is ectoparasite removal. Another meaning that needs to be mentioned is “play”. Play is a valid, but hard to define, behaviour. Definitions of play focus on lack of immediate biological function. What is true is that through playful activities, animals can learn many other important elements of their social life and learn abilities that may be beneficial later in life.
"Fluking", or "fluke-out", is the act of a whale or dolphin raising its tail or fluke above the surface of the water during the beginning of a dive. It’s often played by sperm and humpback whales but even smaller toothed whales, such as bottlenose dolphins, fluke-out before deep dives, propelling their bodies downward.
Fluking or Fluke-out
1st Photo: Sperm Whale / 2nd Photo: Risso's Dolphin
(Photo by Stefano Bellomo)
In conclusion, aerial and surface behaviour may serve a social facilitation function that helps to coordinate members of a school or pod. Such facilitation may be especially useful to animals that coordinate finding and aggregating of food and may need to establish and maintain delicate balances of social and sexual hierarchies.