One of the most interesting traits of the Indo-Pacific humpback dolphin is their colour – or variations that differ between populations, age groups and individuals – from grey to white, even pink.
Some look mottled or albino. Their shallow, coastal and estuarine (often murky water) habitat means they have adapted in some fascinating ways.
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Learn all about these captivating creatures in this fascinating expert guide from Whale and Dolphin Conversation.
Where do Indo-Pacific humpback dolphins live?
Historically, Indo-Pacific humpback dolphins lived in shallow, coastal waters from central China in the east, through south-east Asia and as far west as the east coast of India. Today however, there are thought to be many areas along this route where they are no longer present.
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They strongly prefer estuaries, mangroves, river mouths, and sheltered bays. Unlike oceanic dolphins, they rarely venture far offshore and generally avoid deep open waters.
Why are they called humpbacks?
Their common name comes from the small hump or ridge beneath their dorsal fin, which becomes more pronounced with age. But not all have this pronounced hump.
Their binomial name is Sousa chinensis – ‘Sousa’ comes from the Portuguese naturalist Nicolau Sousa, while ‘chinensis’ refers to the Chinese waters where early studies of the animal were conducted.
What do Indo-Pacific humpback dolphins look like?
Indo-Pacific humpback dolphins are medium-sized dolphins with sturdy bodies, long slender beaks and a distinctive dorsal fin perched on a broad hump. They have a very thick tail stock with distinctive keels on the upper and lower sides.
They are especially noted for their variable colouration, ranging from dark grey in calves to pale grey, white, or even bright pink in adults. The pink hue is caused by blood vessels near the skin surface, which may help regulate body temperature.
Their colour depends on where they live. They all start off as dark grey or black as calves, then their colouration lightens as they get older as they appear to go through a ‘mottling’ stage. Some populations – particularly in China and Thailand – may exhibit pink skin.
How big are they?
They are between 2.3–2.8 metres long and weigh between 200–250kg. Males are at the top end of this scale, with females being slightly smaller.
How many teeth do Indo-Pacific humpback dolphins have?
They have between 29–37 conical teeth on each of both the upper and lower jaws, designed for grasping slippery fish rather than chewing.
What do they eat?
Indo-Pacific humpback dolphin eat a variety of fish, dependant on where they live – such as mullet or sardines. They may also feed on cephalopods such as squid and cuttlefish, and crustaceans like shrimp.
How do Indo-Pacific humpback dolphins track their prey?
Like other dolphins, they use echolocation — producing clicks and interpreting returning echoes to detect prey, even in muddy or low-visibility water. Their eyesight is not great but they make up for this with their excellent hearing that enables them to be highly effective hunters in estuaries.
They are opportunistic hunters, and use a variety of feeding techniques, including partially stranding themselves onshore while chasing fish. Individuals have been seen following fishing trawlers in order to feed on discarded and escaped fish.
Do they form pods or super pods?
These dolphins are usually found alone, in pairs, or in small pods of fewer than 10 individuals. This maybe due to their preferred habitat. Larger temporary groups may gather where food is abundant, but they do not form the enormous super pods seen in some dolphin species that roam the open seas.
How fast can they swim?
They are agile swimmers, typically travelling at 6–8 kmph (4–5 mph), but can sprint much faster when hunting or escaping danger.
Do they come to the surface for long?
They usually surface briefly every few minutes, showing only the dorsal fin and back before slipping beneath the water again. Dives are generally short, often under 5 minutes. They sometimes leap out of or rise vertically from the water surface.
Are they very intelligent?
Like many dolphins, they are highly intelligent – displaying social learning, problem-solving, communication complexity and adaptive hunting techniques.
What sounds do Indo-Pacific humpback dolphins make?
They produce whistles, clicks and a pulse sound for communication and echolocation. Their vocal range is essential for navigating complex coastal habitats and feeding.
Do they interact with other species of whale or dolphin?
They may occasionally associate with bottlenose dolphins, finless porpoises or other coastal dolphin species, though they generally stick with their own species.
How long does the calf stay with its mother?
After a gestation of around 10–12 months, calves may stay close to their mothers for 3–6 years, learning social and feeding behaviours.
Do they have any predators?
Large sharks and killer whales may prey on them, especially calves, though predation is relatively rare compared with human-caused threats. Much depends on where they live.
Given their preference for shallow, coastal waters, they come into contact with humans more regularly than other dolphins might.
How do they protect themselves?
Their best defences are social awareness, agility and staying in shallow water habitats where large predators are less common.
How long do they live?
Indo-Pacific humpback dolphins can live for around 30–40 years in the wild, though some may survive longer.
What are the main threats to Indo-Pacific humpback dolphins?
Human pressures are severe for the Indo-Pacific humpback dolphin, who live in some of the busiest waters in the world. Those in Hong Kong are thought to be some of the most heavily-impacted coastal dolphins globally.
Shipping, habitat degradation (through multiple land reclamation projects) and pollution (both chemical and noise) pose significant threats and the population numbers continue to fall year on year. In some years no calves have been known to survive – possibly due to the pollutant off-load by the mother through her milk.
Are Indo-Pacific humpback dolphins endangered?
Indo-Pacific humpback dolphins are listed by the IUCN as Vulnerable. Many local groups are under serious threat with populations in decline due to deaths from incidental capture in fishing nets and gear, habitat loss, vessel collisions and pollution.
When did Indo-Pacific humpback dolphins first appear?
The dolphins we see today evolved from ancient land mammals over 50 million years ago, but humpback dolphins likely emerged a few million years ago during the Miocene to Pliocene times, when coastal marine habitats expanded and diversified.
When were they described in scientific terms?
The Indo-Pacific humpback dolphin was first formally described in 1765 by Swedish naturalist Pehr Osbeck, who documented specimens from Chinese waters.
What is the scientific name?
The Indo-Pacific humpback dolphin is known scientifically as Sousa chinensis. The term Sousa includes several closely-related humpback dolphin species found in different regions, including the Indian Ocean, Australia and Africa.
The Indo-Pacific humpback dolphin is probably most famous for the striking pink coloration seen in some populations, especially around Hong Kong. But, despite often being called the ‘pink dolphin,’ not all individuals are.
What is the classification?
• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Cetacea
• Family: Delphinidae
• Genus: Sousa
• Species: S. chinensis
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Top image: Getty
