Breaching and lunging File:Anim1091 - Flickr - NOAA Photo Library.jpg|Humpback whale spinner-breaching File:Dwarf sperm whale (NOAA Pitman).jpg|
Dwarf sperm whale breaching File:Killerwhales jumping.jpg|
Orcas double-breaching off the south side of
Unimak Island,
Alaska File:Hector'sDolphinsCloudyBay 21Feb2012 AnjanetteBaker.tif|
Hector's Dolphins off
Cloudy Bay, New Zealand breach sequence A
breach or a
lunge is a leap out of the water, also known as cresting. The distinction between the two is fairly arbitrary: cetacean researcher
Hal Whitehead defines a breach as any leap in which at least 40% of the animal's body clears the water, and a lunge as a leap with less than 40% clearance. Qualitatively, a breach is a genuine jump with an intent to clear the water, whereas a lunge is the result of a fast upward-sloping swim that has caused the whale to clear the surface of the water unintentionally. This latter "lunging" behaviour is often a result of feeding in
rorquals. The right, humpback, and sperm whales are the most widely observed jumpers. However other
baleen whales such as
fin,
blue,
minke,
gray and
sei whales also breach.
Oceanic dolphins, including the
orca, are very common breachers and are in fact capable of lifting themselves completely out of the water very easily, although there is little distinction between this and
porpoising. Some non-cetacean marine creatures also exhibit breaching behavior, such as several shark species and rays of the genera
Manta and
Mobula. Two techniques are used by cetaceans in order to breach. The first method, most common in sperm and humpback whales, is conducted by swimming vertically upwards from depth, and heading straight out of the water. The other more common method is to travel close to the surface and parallel to it, and then jerk upwards at full speed with as few as 3 tail strokes to perform a breach. In all breaches the cetacean clears the water with the majority of its body at an acute angle, such as an average of 30° to the horizontal as recorded in sperm whales. The whale then turns to land on its back or side, and less frequently may not turn but "belly flop" instead. In order to achieve 90% clearance, a humpback needs to leave the water at a speed of eight metres per second or . For a animal, this results in a
momentum of 288 thousand
newton seconds. Despite its energetic cost, breaching is often carried out in series. The longest recorded sustained series was by a humpback near the
West Indies totaling 130 leaps in less than 90 minutes. Repeated breaches tire the animal, so less of the body clears the water each time. Ultimately, the reasons for breaching are unknown; however, there is evidence to support a range of hypotheses. Whales are more likely to breach when they are in groups, suggesting that it is a non-verbal signal to other group members during social behaviour. Scientists have called this theory
"honest signalling". The immense cloud of bubbles and underwater disturbance following a breach cannot be faked; neighbours then know a breach has taken place. A single breach costs a whale only about 0.075% of its total daily energy intake, but a long series of breaches may add up to a significant energy expenditure. Another widely accepted possible reason is to dislodge parasites from the skin. is a high speed surface behaviour of small cetaceans where long jumps are alternated with swimming close to the surface. Despite the name, porpoising behaviour is seen in dolphins and porpoises, as well as other marine species such as
penguins and
pinnipeds. When
marine mammals are travelling at speed they are forced to stay close to the surface in order to maintain
respiration for the energetic exercise. At leisurely cruising speeds below 4.6 m/s, dolphins swim below the water's surface and only briefly expose their
blowholes along with up to one third of their body at any one time. or the direction of incoming boats to avoid collision. Although porpoising is a useful product of rapid swimming, much variation seen in the behaviour cannot be explained by this cause alone; it has likely evolved to provide other functions. For example, the rotation during porpoising by the
spinner dolphin leads to much splashing and is more common at slower speeds When spinner dolphins impact the water the combination of
centrifugal and vertical force upon these
ectoparasites can be up to 700 times their own weight and so efficiently remove them. Research into the additional functions of porpoising has so far been focussed on the more acrobatic species, but it is likely that other cetaceans also use it for these, and perhaps unknown, reasons too.
Wave or bow-riding and following vessels File:091201 south georgia orca 5127 (4173388802).jpg|"Type B" orcas off
South Georgia File:Weißwal 2-1999.jpg|
Belugas following watching boats in
Churchill River File:US Navy 090415-N-3027S-002 Dolphins jump the wake in front of the Military Sealift Command fast-combat support ship USNS Rainer (T-AOE 7) during an ammunition onload with the aircraft carrier USS Nimitz (CVN 68).jpg The term
wave-riding is most commonly used to describe the surface activity of cetaceans that approach boats and jump repeatedly in the waves produced by the boats. This includes
bow-riding, where cetaceans are in the pressure wave in front of the boat, and
wake-riding, where they are off the stern in the wake. Cetaceans swim using fluke propulsion when experiencing wave energy below the threshold needed for riding, such as when boats travel at speeds slower than 3 m/s or when they are outside of the peak wave energy zone. However, at higher speeds dolphins and porpoises will seek out the pressure wave and its maximum energy zone in order to ride the wave by holding their flukes in a fixed plane, with only minor adjustments for repositioning. although most larger Odontocetes do not seek out any form of interaction with boats. Bow-riding is the most common form of interactive behaviour with boats across a variety of smaller Odontocete species, such as dolphins in the genera
Stenella and
Delphinus. The type of interaction can often depend on the behavioral state of the group as well as species. For example, spotted dolphins are more likely to interact when travelling or milling but less likely when they are socialising or surface feeding. This indicates that groups with calves may approach boats in order to teach the young how to interact safely to avoid collision. Another result of cetaceans traveling in pods is an increase in competition for the optimal wave energy and so maximum energy saving position. Position of individuals may reflect the dominance
hierarchy of the pod and therefore could be used to ascertain dominance.
sei,
bryde's,
humpback, and
gray are also known to display actions in similar manners.
Gallery • Jumping dolphins == Stationary surface behaviour ==