Dolphins and whales are, in our imagination, notoriously aerially acrobatic animals. While play may at times be a cause of leaping and other surface activities, there are multiple aerial behaviour types and the reasons for them are not fully understood. Leaping and breaching are, maybe, the most discussed and well know aerial behaviour but there are many other aerial (or surface) behaviour that are crucial in the social life of cetaceans. Lunging, spy hopping, slapping flukes and flippers onto the water surface (lobtailing and flipper slapping), porpoising, and lifting the flukes clear of the water, or fluking: let’s discover the meaning of the aerial and surface behaviour of cetaceans and the importance in their lives.
Let’s start with the “breaching”. First of all, we need to be more specific. 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. 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. 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. Breaches are often performed in bouts, up to 130 breaches in 75 min have been recorded for one humpback whale. As individual bouts progress, animals tend to show less of their bodies, visibly appearing fatigued. 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, with full bodies above the water at times. The best correlate of breaching rate appears to be 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. In a number of 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. It generally bends its body abruptly to exit the water and then twists the body mid-air to reenter the water in some structured fashion. 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.
Finally, there are the “showy” acrobatic leaps that consist of spins, somersaults, and various in-air twists. Frame-by-frame analysis of high-speed photographs shows that dolphins control these acrobatics to within split-second timing, affecting muscle movements that allow them to perform the same leap and reentry onto the water multiple times. 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 about 7 m into the air. These leaps may be performed largely for “fun”, 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. Some dolphins are especially showy for some of their leaps, with spins, somersaults, combinations of flips, head twists, extra tail kicks in-air, and so on. These leaps are usually associated with a high level of social activity in a school or pod, as evidenced by social rubbing, sexual activity, and whistling and other sounds. Acrobatic leaps usually occur in bouts, with one dolphin leaping several times. The more social the group, the more leaping dolphins, and the longer the individual bouts. As we said, the striped and spotted dolphins is the champion in reaching the highest jumps but one dolphin leaps in a so particular way that from this behaviour came its name: the spinner dolphin. These animals rotate their body rapidly around its long axis up to seven times before falling back into the water. They do so in vertical spins as well as in a horizontal fashion. Species of the genus Lagenorhynchus, such as dusky dolphins, need to be mentioned because they are among the most aerially acrobatic of all dolphins. 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 instance when male humpback whales physically compete for mates. Dolphins that play around the eyes and mouths of whales, at times apparently do so to elicit lunging from the whales, so that they can ride the “bow-wave” of the lunging whales.
Porposing is the way that fast swimmers as the striped dolphins swim rising above it and submerging really fast. This behaviour is mostly connected with feeding or when young individuals play chasing one each other or when anadult 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 in-air environment.
Lobtailing or tail slapping consists of forcefully slapping the tail onto the surface of the, either venter or dorsum up. While the beat frequency in large whales can be quite slow, on the order of several to as many as 10 s between slaps, in dolphins it can be up to one or slightly more per second. 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. Sperm, right, bowhead, humpback, and gray whales are “frequent” lobtailers. For the smaller cetaceans, delphinids are champions at lobtailing and other aerial behaviors.
Flipper slapping by whales and dolphins occurs, similar to 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.
Especially active behaviors 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, “extreme annoyance” (perhaps with a nearby vessel), an “act of defiance,” courtship, or a display of strength by males. A breach may be used to add emphasis to some other signal, perhaps a vocalization or visual display. By showing the extent of its physical prowess, and expending a significant amount of energy, the whale accentuates the importance of a companion signal. 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 (when in “noisy” fashion), lobtailing, and flipper slapping may help cetaceans feed by scaring, stunning, herding, or trapping fish or other prey. Another benefit of breaching/leaping is ectoparasite removal. Baleen whales are the more heavily infested species and tend to be the most frequent breachers and also dolphins, which can have remoras attached, but still, the main reason of these jumps communication, even if, we need to mention another meaning: play. Play is a valid, but hard to define, behavior. Definitions of play focus on lack of immediate biological function, but many aerial activities described by human observers as “playful” may actually function as important signals. What is true is that through playful activities, animals can learn many other important elements of their social life, learning abilities that may be beneficial later in life.
The "body language" of cetaceans may have, as well, a specific function and they may be aggresive. That's the case of the Risso's dolphins when they want to approach a female. To fight against other males or to approach a female, they may become more aggressive and the leaping become a real bullchasing, as showed in the following pictures.
Another species that is used to show aggressive behaviour against other individuals of the same species, fighting for a female, for resources as food or for still unknown reasons, is the bottlenose dolphins. Here, in this picture, two individuals fighting and one licterally jumping out of the water shoting with its head the other one.
Another surface behaviour is named fluking. It is the act of a whale or dolphin raising its tail, or flukes, above the surface of the water during the beginning of a dive. There is great variability in fluking behavior by species: humpback and sperm whales almost always “fluke out” during the dive; minke and fin whales do so rarely Right, bowhead, and gray whales vary the amount and type of fluking depending on whether they are feeding near the surface (no fluking), at moderate depth (occasional fluking), or at depths of 60 m or more (“always” fluking). These species also generally fluke on migration, during the final dive after a series of “near-surface” dives between respirations. Even smaller toothed whales, such as bottlenose dolphins and pilot whales, fluke at times before deep or at least steeply dives. In smaller delphinids, however, fluking probably has a distinct advantage during the initiation of the dive: the tail and tail stock (or caudal peduncle) held above the surface provide in-air weight to the body and help propel it downward.
A “pre-dive flex” of the body of cetaceans takes about 2 s and often occurs just before the last blow before a dive. The predive flex is usually predictive of a fluke out dive and the flukes out indicate steep, generally deep, diving for feeding or migrating.
As explained in the article of the photo-identification, flukes of whales and dolphins have thin trailing edges (similar to the trailing edges of dorsal fins) and are easily marked by, for example, conspecific interactions or touching other objects. These marks make individual recognition of the flukes possible in those species that habitually fluke out, and fluke-based photographic identification is being practiced for sperm, humpback, and gray whales.
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. This is the real meaning of the spectacular behaviours of cetaceans. We, humans, need to keep it in mind because the only way to observe it is when these animals are free in the open sea or ocean and not trapped in a pool, where these behaviours are, firstly, less spectacular and without any social meaning and where they are just realized forcing these amazing animals to do them, just to receive some not healthy food back after them. Here, in these tanks, these animals are used as clowns and their life is synonymous of suffering because they are extremely conscious mammals that, when in the wild, swim for hundreds of kilometres everyday, looking for other groups of cetaceans and playing with the individuals of their family. In the pools, they spend a life in prison without having committed any crime.
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