Humpback dolphins: S. chinensis and S. teuszii

This chapter discusses the characteristics, taxonomy, distribution, abundance, and ecology of humpback dolphins or S. chinensis and S. teuszii. Humpback dolphins are medium-sized delphinids found in coastal waters of the eastern Atlantic, Indian, and West Pacific oceans. Genetic and morphological information indicate that they are delphinids (family Delphinidae). Humpback dolphins are characterized by a robust and medium-sized body. The melon is moderate in size, slightly depressed, and in profile slopes gradually to an indistinct junction with the long, narrow rostrum. The broad flippers are rounded at the tip and the flukes are broad and full, with a deep median caudal notch. Dorsal and ventral ridges on the caudal peduncle are well developed in African and Indian Ocean populations. Overall, humpback dolphins reach a maximum total length of 2.6-2.8 m in different parts of their distribution. A few animals exceeding 3.0 m in length have been recorded in the Arabian and Indian regions. Maximum weights of 250-280 kg have been recorded for humpback dolphins in South Africa and Hong Kong. Humpback dolphins swim slowly at about 5 km/h, surfacing briefly at intervals of up to a minute. Socializing in humpback dolphins is characterized by individuals in close proximity showing high levels of physical interaction including body contact and frequent aerial behavior such as leaps and somersaults. Fins and flukes often break the surface of the water.