Sousa teuszii, Atlantic Hump-backed Dolphin [+]

Kingdom Animalia Phylum Chordata Class Mammalia Order Cetacea Family Delphinidae Genus Sousa species: Sousa teuszii [+ITIS +WoRMS]

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Description & Behavior

Atlantic hump-backed dolphins, Sousa teuszii (Kükenthal, 1892), measure a maximum of 2.5 m in length and weigh about 150 kg. They are slate to pale gray in color on the dorsal side with some speckled markings and lighter coloring on the ventral side. They have a long beak, large melon, and well-rounded flippers. Their common name comes from the shape of their unique dorsal fin, which measures about 15 cm high and curves to form a distinct hump. The pectoral fins measure about 30 cm in length, and the flukes are about 45 cm wide.

Because of their geographic location in Africa near areas of civil strife, Atlantic hump-backed dolphins have not been widely studied.

Atlantic hump-backed dolphins have 26-31 pairs of homodont (all teeth are the same), peg-like teeth in each jaw. They also have fewer vertebrae than their sister species. Tooth count and vertebrae, along with geographical location, are the major distinguishing characteristics between Sousa teuszii and the Indo-Pacific hump-backed dolphin, Sousa chinensis.

Sousa teuszii is known to swim more slowly than other species in the Delphinidae family. They dive for periods up to 3 minutes and are known to jump out of the water. Other characteristics common to Delphinidae include their high brain to body mass ratio, which is higher than that of other mammals and thought to be an indication of intelligence. Like other dolphins, they are equipped with echolocation to locate prey and communicate.

Off the coast of Mauritania, this species has established an equitable partnership with local fishermen. Atlantic hump-backed dolphins herd schooling fish closer to the shore when signaled by fishermen, this allows the fishermen to net the fish and the dolphins to feed freely.

World Range & Habitat

The Atlantic hump-backed dolphin, Sousa teuszii, is found off the coast of west Africa from Mauritania to Angola. This species prefers shallow coastal waters, river channels, and estuaries. This is a somewhat solitary species and have been observed traveling and feeding alone, however small groups of 3-7 and larger groups of 20-25 have also been reported, generally these groups consist of younger Atlantic hump-backed dolphins.

It is thought that Atlantic hump-backed dolphins stay near the shore to avoid predation by orca (killer whales) that use echolocation to find the dolphins given that the presence of land interferes with echolocation. Atlantic hump-backed dolphins have been known to seek refuge in reefs and near the ocean bottom in deeper waters.

» GBIF occurrence data in Google Earth [Tips] | Ocean Biogeographic Information System (OBIS) (World Distribution) [about]

Feeding Behavior (Ecology)

The Atlantic hump-backed dolphin, Sousa teuszii, feeds on schooling fish such as herrings, sea breams, sardines, and mullet. When feeding in groups, they herd their prey close to land, which decreases the ability for prey to escape.

Life History

The reproductive patterns of the Atlantic hump-backed dolphin, Sousa teuszii, are not well known. Calving has been recorded from December through February but also may occur year-round.

Conservation Status/Additional Comments

Like other dolphin species, the Atlantic hump-backed dolphin, Sousa teuszii, is at-risk of being caught in fishing gear, and their proximity to the shoreline causes them to get caught in "anti-shark" nets set up to protect beachgoers. Coastal development may also reduce the habitat of this species forcing populations to decrease.