The warmer, sheltered waters of False Bay, compared to the West Coast, attract the common dolphin, bottlenose dolphins and humpback dolphins — the latter being South Africa’s most endangered dolphins.
What is the difference between a humpback and a bottlenose dolphin? As the name suggests, this species of dolphin has a hump upon which the dorsal fin is found. The dorsal fin of a humpback dolphin is not only smaller, but their overall colouration is also a lighter shade of grey than that of a bottlenose dolphin. This species also has a distinctive way of surfacing whereby its beak comes completely out of the water before the head. Both species reach lengths over 2.5 meters with males being larger than females.
Bottlenose and humpback dolphins prefer shallow water between 15 and 30 meters deep and as such are regularly seen close to shore, usually just behind or on the last breaker. They have a preference for reef systems and areas close to river mouths. These represent productive ecosystems that would provide them with food including fish species such as snapper kob, grunter, stumpnose and glassnose depending on where along the South African coast they are.
If you see a large disturbance on the water surface, chances are good that this is caused by a large pod of Common Dolphins:
Physical Description & Colour
Common dolphins are most closely related to Porpoises and Whales but can easily be identified by their bright, colour-contrasting patterns. The sides are light grey in colour behind the dorsal fin, and a yellowish-tan colour in front of the dorsal fin which creates their distinct hourglass pattern. The back is dark grey-to-black in colour, stretching from the top of the head to the tail and dipping to a V on the sides below the dorsal fin. The belly is white in colour. Common Dolphins have slender but solid bodies, with a long beak and a pointed triangular-shaped dorsal fin located in the middle of the back.
Length & Weight
Common dolphins are relatively small dolphins that can reach lengths of 1.9 and 2.6 metres, and weigh between 80 kg and 235 kg. At similar ages, the males are slightly larger than the females.
Common dolphins are found in all tropical and warm-temperate waters. The long-beaked common dolphin, which is the species that we often see, is found in more coastal waters; and the short-beaked common dolphin is mainly found in offshore waters.
Mating & Breeding
Common dolphins normally reach sexual maturity between 3 to 4 years of age, or when they reach 1.8 to 2.1 metres in length. Females normally give birth to a single calf after a 10 to 11-month gestation period. The calves are normally around 76 to 86 cm in length at birth and weigh around 10 kg.
Common dolphins are active predators and their diet mainly consists of squid and small schooling fish, such as anchovies, sardines and pilchards. Small groups of common dolphins may work together to herd schools of prey, and they are often associated with diving birds and feeding whales.
Common dolphins are usually found in large social groups of between 100 and 500 animals but have occasionally been seen in larger groups of thousands of individuals. They are fast swimmers and are often seen breaching and porpoising out of the water. They will also often approach ships to “bow-ride” for long periods of time.