Sri Lanka's Amazing Maritime

Courtship

Spinner dolphins

Dolphin Species Information

Orca

Length: 5.5-7.5m, max. 9.8m

Weight: 3-6t, max. 7.4-9.8t

Common Names

English: orca, killer whale

Sinhala: makara komaduva, talgas mulla

Tamil: killer thimingilam

Classification

Class: Mammalia Order: Cetacea

Suborder: Odontoceti Family: Delphinidae

Scientific name: Orcinus orca (Linnaeus, 1758)

Sightings

Regular. All year round. Best between December and April (north western to southern seaboard).

Transients have been seen passing along the west coast of Sri Lanka, above or just off the continental shelf, mostly between December and April. Orcas are also sighted off the east coast in September. Other nearby haunts of this cosmopolitan species include the Arabian Sea and the Bay of Bengal, including Ninety East Ridge.

Orca distribution by month

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Short-Finned Pilot Whale

Length: 3.7-6m, max. 7.2m

Weight: 1-3t, max. 3.6t

Common Names

English: short-finned pilot whale, pothead whale

Sinhala: komaduva

Classification

Class: Mammalia Order: Cetacea

Suborder: Odontoceti Family: Delphinidae

Scientific name: Globicephala macrorhynchus (Gray, 1846)

Sightings

Occasional, December to June.

Short-finned pilot whales are generally found in deep waters, but move inshore as near as 10km when travelling along the west coast of Sri Lanka. They are known to be nomadic, with no fixed migratory routes, and are widely distributed in the south-eastern Arabian Sea, the Laccadive Sea, the Bay of Bengal and the ocean south of Sri Lanka.

Its scarred body and blunt, squared-off head make an adult Risso’s dolphin unmistakable, though when seen from a distance it may be confused with other large dolphins that sport tall dorsal fins, such as bottlenose dolphins, false killer whales and orcas.

Short-finned Pilot whale GPS records (POIs)

Pilot whale distribution by month

Pilot whale distribution by depth

Pilot whale distribution by month

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Taxonomic Notes

It is believed that there is evidence of at least two separate subspecies of G. macrorhynchus, but further examination is required to confirm this (Taylor et al., 2014).

Risso's Dolphin

Length: 2.8-3.2m, max. 3.8m

Weight: 300kg, max. 500kg

Common Names

English: Risso's dolphin

Sinhala: Risso’s mulla, malina mulla

Tamil: narai oonjia, panavi meen

Classification

Class: Mammalia Order: Cetacea

Suborder: Odontoceti Family: Delphinidae

Scientific name: Grampus griseus (Cuvier, 1812)

Sightings

All year round. Regular.

Resident (breeding population) but may also be migratory. It is pelagic, usually found in deep oceanic and continental slope waters. Present year-round through most of its range, with some evidence of seasonal movement on the continental shelf in areas such as the Gulf of Mannar. Widely distributed in the Laccadive Sea, off southern Sri Lanka and the Bay of Bengal.

Risso's dolphin monthly distribution

Risso's dolphin depth distribution

Risso's dolphin monthly distribution

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Common Bottlenose Dolphin & Indian Ocean Bottlenose Dolphin

Common bottlenose dolphin, Tursiops truncatus

Length: 2-3.1m, max. 3.9m

Weight: 180-300kg, max. 650kg

Indian Ocean bottlenose dolphin, Tursiops aduncus

Length: 2-2.7m, max. 3.2m

Weight: 180-240kg, max. 400kg

Common Names

English: bottlenose dolphin, common bottlenose dolphin

Sinhala: bothal hota mulla, samaanya bothal hota mulla

Tamil: kuppi mukkinai oonjia

Classification

Class: Mammalia Order: Cetacea

Suborder: Odontoceti Family: Delphinidae

Scientific name: Tursiops truncatus (Montagu, 1821)

Common Names

English: Indian Ocean bottlenose dolphin, Indo-Pacific bottlenose dolphin

Sinhala: Indian samudhra bothal hota mulla

Tamil: kuppi mukkinai oonjia

Classification

Class: Mammalia Order: Cetacea

Suborder: Odontoceti Family: Delphinidae

Scientific name: Tursiops aduncus (Ehrenberg, 1833)

Sightings

All year round. Common; abundant off south coast.

Widely distributed all round Sri Lanka in coastal and continental-shelf waters. Population density appears to be higher near to shore. In some areas, common bottlenoses may have limited home ranges; in others, they may be nomadic, accompanying pilot whales as they travel the deep ocean.

There may be two ‘ecotypes’ of the common bottlenose dolphin: a smaller and lighter inshore form and a larger, slightly darker-coloured offshore form.

Seen at close range, common bottlenose dolphins can clearly be distinguished from Indian Ocean bottlenose dolphins by their key characteristics (refer 'Out of the Blue'). They can also be mistaken for humpback dolphins, but will often be distinguishable by differences in body shape, size and behaviour. When seen from a distance, they can also be confused with Risso’s or rough-toothed dolphins.

Sightings

All year round. Occasional.

Though rarely recorded, possibly due to confusion with the common bottlenose and the recent split in taxonomy, Indian Ocean bottlenose dolphins are thought to be fairly common in Sri Lankan waters. They are found primarily over the continental shelf and appear to prefer shallow inshore waters throughout their range.

The slender appearance, sharply contrasting grey dorsal cape with a spinal blaze, lighter belly and relatively longer, thinner rostrum distinguish members of this species from the common bottlenose. Indian Ocean bottlenose dolphins can be mistaken for pan-tropical spotted dolphins and humpback dolphins, but will often be distinguishable by differences in body shape, size and behaviour. From a distance, they may also be confused with Risso’s or rough-toothed dolphins.

B'nose dolphins monthly distribution

B'nose dolphins depth distribution

B'nose dolphins monthly distribution

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Fraser's Dolphin

Length: 2-2.6m, max. 2.7m

Weight: 150-180kg, max. 210kg

Common Names

English: Fraser's dolphin

Sinhala: Fraser's mulla

Tamil: Fraser's oonjia

Classification

Class: Mammalia Order: Cetacea

Suborder: Odontoceti Family: Delphinidae

Scientific name: Lagenodelphis hosei (Fraser, 1956)

Fraser's dolphin monthly distributio

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The unique body shape and stocky beak of the Fraser’s dolphin should rule out confusion with other species; striped dolphins also have an eye-to-anus stripe but have a longer beak.

Sightings

All year round. Ocassional.

Fraser’s dolphin typically inhabits the high seas and feeds in deep oceanic waters. Members of the species rarely stray into the relatively shallow water over a continental shelf.

Humpback Dolphin

Length: 1.8-2.7m, max. 2.8m

Weight: 60-240kg, max. 280kg

Common Names

English: Indo-Pacific humpbacked/humpback dolphin, Chinese white dolphin (pink dolphin), plumbeous humpback dolphin

Sinhala: kabara mulla

Tamil: koon muthuku oonjia

Classification

Class: Mammalia Order: Cetacea

Suborder: Odontoceti Family: Delphinidae

Scientific name: Sousa plumbea (Cuvier, 1829)

Taxonomic Notes

There are at least two species in the Indo-Pacific area: S. plumbea (Cuvier, 1829) in the western Indian Ocean from South Africa to at least the southeast coast of India, and S. chinensis from the east coast of India to China and Australia. Current understanding is that humpback dolphins in the Gulf of Mannar are members of the western Indian Ocean subspecies, S. plumbea. The two geographic forms differ markedly in their external morphology (iucn 2012). Current studies, both morphological and genetic, were being carried out at time of writing to determine the number of species in this genus.

Humpback dolphin monthly distributio

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Humpback dolphins are most likely to be confused with bottlenose dolphins due to similarities in the head region. Differences in dorsal fin shape (including the hump when present), head shape and colour all help distinguish between the two species. Also, humpbacks tend to surface differently, pausing at the top of their roll.

Sightings

All year round. Common.

inshore waters and estuaries at depths of up to 25m. Most commonly found in large aggregations along Adam’s Bridge. In Kalpitiya, a pod of up to five regularly enters Dutch Bay and Puttalam Lagoon to feed. Other unconfirmed reported sightings off Chilaw and Yala.

Striped Dolphin

Length: 1.8-2.5m, max. 2.6m

Weight: 60-150kg, max. 160kg

Common Names

English: striped dolphin

Sinhala: wairam mulla

Tamil: koditta oonjia

Classification

Class: Mammalia Order: Cetacea

Suborder: Odontoceti Family: Delphinidae

Scientific name: Stenella coeruleoalba (Meyen, 1833)

Striped dolphin monthly distribution

Striped dolphin depth distribution

Striped dolphin monthly distribution

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The striped dolphin, with its unique colour pattern, is generally easy to distinguish from Fraser’s dolphin, which also bears an eye-to anus stripe but is much more robust, with tiny appendages.

Sightings

All year round. Occasional.

Oceanic (pelagic). May occasionally be seen close to shore, but only where the water immediately offshore is deep. Widely distributed in the Laccadive Sea and in the waters south and east of Sri Lanka.

Spinner Dolphin

Length: 1.6-1.9m, max. 2.3m

Weight: 50-80kg, max. 100kg

Common Names

English: spinner dolphin, Sri Lankan spinner dolphin, long-snouted spinner dolphin, Gray’s dolphin

Sinhala: karekena mulla

Tamil: sullel oonjia

Classification

Class: Mammalia Order: Cetacea

Suborder: Odontoceti Family: Delphinidae

Scientific name: Stenella longirostris (Gray, 1828)

Taxonomic Notes

Four subspecies of the spinner dolphin, Stenella longirostris, are recognised. These are geographically defined and differ in body shape, size and colour. The subspecies known as the Gray’s or Hawaiian spinner dolphin, S.l. longirostris, with its typical tripartite colour pattern, is thought to be the subspecies present in Sri Lanka. Some spinner dolphins in Sri Lanka and Maldives, however, show a dark lateral stripe between their medium-grey flanks and belly. Representatives of subspecies, or other undescribed stocks, may exist here – and elsewhere in the world as well.

Spinner dolphin monthly distribution

Spinner dolphin depth distribution

Spinner dolphin monthly distribution

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Sightings

All year round. Extremely abundant; extremely so off Kalpitiya peninsula where they are most acrobatic.

Breeding residents, widely and abundantly distributed all round Sri Lanka and in adjacent waters. Superpods and even megapods which were frequently seen off Kalpitiya are now only seen infrequently.

Spinner dolphins can be easily distinguished by differences in size, dorsal-fin shape, beak length. three-toned colour pattern, and particularly by their characteristic behaviour.

Dugong

Length: 2.4-2.7m, max. 3m

Weight: 230-400kg, max. 545kg

Common Names

English: dugong, sea cow. Also known as: lady of the sea

Sinhala: muhudhu oora

Tamil: kadal panni, orgil, avilliya

Classification

Class: Mammalia Order: Sirenia

Suborder: Trichechiformes Family: Dugongidae

Scientific name: Dugong dugon (Müller, 1776)

There is some slight possibility of confusion with the finless porpoise, but in addition to behaviour and size, the single blowhole of the porpoise and the double nostrils of the dugong allow the two species to be easily distinguished.

Sightings

All year round. Very rare.

Warm, shallow coastal waters and estuaries with healthy ecosystems that support large beds of seagrass and/or other vegetation. Habitats in Indo-Sri Lankan waters include Palk Bay and the Gulf of Mannar north of Pukkulum, with strays sometimes entering Dutch Bay. During the monsoon, they typically inhabit the lee side of the Arippu pearl banks, Adam’s Bridge, Palk Bay and the islands west of Jaffna, where they can avoid strong winds and heavy seas. When calm weather returns, they move into the open sea, though still remaining in waters no deeper than 15m.

Dugong catches monthly distribution

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