What is a whale?
The Humpbacks of Hermanus
A Humpback whale grows to about 16 m and weighs between 24 and 45 tonnes. They eat about 2 tonnes of plankton, krill and small fish twice a day every day during the feeding season (about 120 days).
In order to achieve 90% clearance, a humpback needs to leave the water at a speed of eight meters per second or 29 kilometres per hour (18 mph). For a 36 metric tons (40 short tons) animal, this results in the 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 totalling 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.
Breaching
This is when the whales jump; they can lift three quarter or more of their body out of the water. Normally breaching is done three or five times in succession. It is unknown why whales do this, but some experts claim that it could be that they are sloughing lice from their skin, part of the mating ritual, or simply high spirits.
Lobtailing
This is when they lie on their sides and sail one fin. It could be for communication with other whales or to regulate their body temperature, but either way, the sound of the whales tail slapping down on the water is truly impressive.
Sailing
This is when the whales stick their tails out of the water and “sail” across the sea. It is almost certainly a way of regulating body temperature.
Skyhopping
This is when the whales bob their head and part of their bodies up and out of the water. Southern Rights are “sight and sound” whales and don’t possess sonar. It is possible that skyhopping has a navigational purpose or simple curiosity.
Blowing
This is when whales exhale air out of their blowholes along with water vapour. The shape of the spout of water enables us to identify what species of whale it is. The Southern Rights have a distinctive V-shaped blow.
Playing with kelp
Whales seem to enjoy playing with kelp and rubbing it over their backs and heads, possibly removing old skin and lice.
Grunting
This sound can be heard a couple of kilometres away and is often heard at night.