On any given day in Gansbaai, a pod of dolphins may appear without warning — a glimpse of a dorsal fin in the distance or individuals leaping right alongside our shark cage diving boat.

Globally, there are 38 recognised species of oceanic dolphins. Along South Africa’s coastline, 18 species have been recorded, three of which can be spotted in Gansbaai: the Indo-Pacific Bottlenose Dolphin, the Long-beaked Common Dolphin, and the Indian Ocean Humpback Dolphin.

In this blog, we explore the Indo-Pacific Bottlenose Dolphin and its close relative, the Common Bottlenose Dolphin. There is also a third possible species of bottlenose dolphin (genus Tursiops), first described in 2011, known as the Burrunan Dolphin, which is found in Australia.

As their name suggests, bottlenose dolphins have a “bottle-shaped” snout, which is short and stubby compared to other dolphin species. The Indo-Pacific species has a slightly longer snout than the Common Bottlenose Dolphin.

Both species are dark grey along their backs (with the Common Bottlenose Dolphin typically darker), fading to a lighter grey on their bellies. As they mature, Indo-Pacific Bottlenose Dolphins may develop a spotted pattern on their underside.

This species is generally smaller and more slender. Both species have a distinctive hook-shaped dorsal fin.

Common Bottlenose Dolphins have a wide distribution across tropical and temperate waters of the Atlantic, Pacific, and Indian Oceans, inhabiting both inshore and offshore environments.

In contrast, Indo-Pacific Bottlenose Dolphins are more restricted to warmer, shallower waters of the Indian Ocean and western Pacific Ocean.
Bottlenose dolphins typically travel in pods of 10 to 30 individuals, while coastal populations often form smaller groups of 2 to 15.

Their social structure is highly dynamic and known as a fission-fusion society, where groups frequently split and merge.

Occasionally, bottlenose dolphins form large temporary superpods of over 1,000 individuals. These aggregations occur to maximise feeding opportunities, increase protection from predators such as sharks, and enhance social and breeding interactions.

They are opportunistic feeders, meaning their diet varies depending on location and season. Their diet includes fish, cephalopods, and crustaceans.

Dolphins use a variety of hunting techniques, including strand feeding, stunning prey with their tail flukes, and in Shark Bay, Western Australia, a small population of Indo-Pacific Bottlenose Dolphins were found using marine sponges as tools to protect their snouts while foraging.

Conservation Status

According to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, the Common Bottlenose Dolphin is listed as Least Concern, while the Indo-Pacific Bottlenose Dolphin is listed as Near Threatened.

Threats include climate change, pollution, entanglement in shark nets, bycatch in fisheries, and habitat degradation due to coastal development.

Why Bottlenose Dolphins Matter

As apex predators, bottlenose dolphins play a vital role in maintaining healthy marine ecosystems and are indicators of ocean health. They are frequently seen along South Africa’s coastline, making them an important species for marine tourism and ecotourism.