Community hub
Recent from talks
Knowledge base stats:
Talk channels stats:
Members stats:
Irrawaddy dolphin
The Irrawaddy dolphin (Orcaella brevirostris) is a euryhaline species of oceanic dolphin found in scattered subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia. It closely resembles the Australian snubfin dolphin (of the same genus, Orcaella), which was not described as a separate species until 2005. It has a slate blue to a slate gray color. Although found in much of the riverine and marine zones of South and Southeast Asia, the only concentrated lagoon populations are found in Chilika Lake in Odisha, India, and Songkhla Lake in southern Thailand.
One of the earliest recorded descriptions of the Irrawaddy dolphin was by Sir Richard Owen in 1866, based on a specimen found in 1852 in the harbour of Visakhapatnam on the east coast of India. It is one of two species in its genus. It has sometimes been listed variously in a family containing just itself and in the Monodontidae and Delphinidae. Widespread agreement now exists to list it in the family Delphinidae.
The species' name, brevirostris, is from the Latin meaning "short beaked".[citation needed]
The Irrawaddy dolphin's colour is grey to dark slate blue, paler underneath, without a distinctive pattern. The dorsal fin is small and rounded behind the middle of the back. The forehead is high and rounded; the beak is lacking. The front of its snout is blunt. The flippers are broad and rounded. The finless porpoise (Neophocaena phocaenoides) is similar and has no back fin; the humpback dolphin (Sousa chinensis) is larger and has a longer beak and a larger dorsal fin. It ranges in weight from 90 to 200 kg (200 to 440 lb) with a length of 2.3 m (7.5 ft) at full maturity. The maximum recorded length is 2.75 m (9.0 ft) of a male in Thailand.
The Irrawaddy dolphin is similar to the beluga in appearance, though most closely related to the killer whale. It has a large melon and a blunt, rounded head, and the beak is indistinct. Its dorsal fin, located about two-thirds posterior along the back, is short, blunt, and triangular. Dorsal fin shapes differ from one Irrawaddy dolphin to another. The flippers are long and broad. These dolphins are usually two-toned, with the back and sides being gray to bluish-gray and the belly lighter. Unlike any other dolphin, the Irrawaddy's U-shaped blowhole is on the left of the midline and opens towards the front of the dolphin. Its short beak appears very different from those of other dolphins, and its mouth is known for having 12-19 peg-like teeth on each side of the jaws.
Communication is carried out with clicks, creaks, and buzzes at a dominant frequency of about 60 kilohertz, which is thought to be used for echolocation. Bony fish (including catfish) and fish eggs, cephalopods (such as squid, octopus, and cuttlefish), and crustaceans are taken as food. Observations of captive animals indicate food may be taken into the mouth by suction. Irrawaddy dolphins are capable of squirting streams of water that can reach up to 1.5 metres (4 ft 11 in); this distinct behaviour has been known for herding fish into a general area for hunting. They do this sometimes while spyhopping and during feeding, apparently to expel water ingested during fish capture or possibly to herd fish. Some Irrawaddy dolphins kept in captivity have been trained to do spyhopping on command. The Irrawaddy dolphin is a slow swimmer, but swimming speeds of 20–25 kilometres per hour (12–16 mph) were reported when dolphins were being chased in a boat. In a year, females can sometimes swim as far as an average of 45 kilometres (28 mi), and males can swim up to an average of 100 kilometres (62 mi).
Most Irrawaddy dolphins are shy of boats, not known to bow-ride, and generally dive when alarmed. They are relatively slow-moving but can sometimes be seen spyhopping and rolling to one side while waving a flipper and occasionally breaching. They are generally found in groups of 2-3 animals, though sometimes as many as 25 individuals have been known to congregate in deep pools. Groups of fewer than six individuals are most common, but sometimes up to 15 dolphins are seen together. Traveling and staying in groups not only enables Irrawaddy dolphins to hunt, but it also creates and maintains social bonds and allows copulation to occur. There are a few groups of dolphins in Brunei Bay seen near the mouths of the Temburong and Aloh Besar rivers, which are tame and gather around fishermen's boats that catch fish during the fishing season from around December to February.
It surfaces in a rolling fashion and lifts its tail fluke clear of the water only for a deep dive. Deep dive times range from 30 to 150 seconds to 12 minutes. When 277 group dives were timed (time of disappearance of the last dolphin in the group to the emergence of the first dolphin in the group) in Laos, the mean duration was 115.3 seconds with a range of 19 seconds to 7.18 minutes.
Hub AI
Irrawaddy dolphin AI simulator
(@Irrawaddy dolphin_simulator)
Irrawaddy dolphin
The Irrawaddy dolphin (Orcaella brevirostris) is a euryhaline species of oceanic dolphin found in scattered subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia. It closely resembles the Australian snubfin dolphin (of the same genus, Orcaella), which was not described as a separate species until 2005. It has a slate blue to a slate gray color. Although found in much of the riverine and marine zones of South and Southeast Asia, the only concentrated lagoon populations are found in Chilika Lake in Odisha, India, and Songkhla Lake in southern Thailand.
One of the earliest recorded descriptions of the Irrawaddy dolphin was by Sir Richard Owen in 1866, based on a specimen found in 1852 in the harbour of Visakhapatnam on the east coast of India. It is one of two species in its genus. It has sometimes been listed variously in a family containing just itself and in the Monodontidae and Delphinidae. Widespread agreement now exists to list it in the family Delphinidae.
The species' name, brevirostris, is from the Latin meaning "short beaked".[citation needed]
The Irrawaddy dolphin's colour is grey to dark slate blue, paler underneath, without a distinctive pattern. The dorsal fin is small and rounded behind the middle of the back. The forehead is high and rounded; the beak is lacking. The front of its snout is blunt. The flippers are broad and rounded. The finless porpoise (Neophocaena phocaenoides) is similar and has no back fin; the humpback dolphin (Sousa chinensis) is larger and has a longer beak and a larger dorsal fin. It ranges in weight from 90 to 200 kg (200 to 440 lb) with a length of 2.3 m (7.5 ft) at full maturity. The maximum recorded length is 2.75 m (9.0 ft) of a male in Thailand.
The Irrawaddy dolphin is similar to the beluga in appearance, though most closely related to the killer whale. It has a large melon and a blunt, rounded head, and the beak is indistinct. Its dorsal fin, located about two-thirds posterior along the back, is short, blunt, and triangular. Dorsal fin shapes differ from one Irrawaddy dolphin to another. The flippers are long and broad. These dolphins are usually two-toned, with the back and sides being gray to bluish-gray and the belly lighter. Unlike any other dolphin, the Irrawaddy's U-shaped blowhole is on the left of the midline and opens towards the front of the dolphin. Its short beak appears very different from those of other dolphins, and its mouth is known for having 12-19 peg-like teeth on each side of the jaws.
Communication is carried out with clicks, creaks, and buzzes at a dominant frequency of about 60 kilohertz, which is thought to be used for echolocation. Bony fish (including catfish) and fish eggs, cephalopods (such as squid, octopus, and cuttlefish), and crustaceans are taken as food. Observations of captive animals indicate food may be taken into the mouth by suction. Irrawaddy dolphins are capable of squirting streams of water that can reach up to 1.5 metres (4 ft 11 in); this distinct behaviour has been known for herding fish into a general area for hunting. They do this sometimes while spyhopping and during feeding, apparently to expel water ingested during fish capture or possibly to herd fish. Some Irrawaddy dolphins kept in captivity have been trained to do spyhopping on command. The Irrawaddy dolphin is a slow swimmer, but swimming speeds of 20–25 kilometres per hour (12–16 mph) were reported when dolphins were being chased in a boat. In a year, females can sometimes swim as far as an average of 45 kilometres (28 mi), and males can swim up to an average of 100 kilometres (62 mi).
Most Irrawaddy dolphins are shy of boats, not known to bow-ride, and generally dive when alarmed. They are relatively slow-moving but can sometimes be seen spyhopping and rolling to one side while waving a flipper and occasionally breaching. They are generally found in groups of 2-3 animals, though sometimes as many as 25 individuals have been known to congregate in deep pools. Groups of fewer than six individuals are most common, but sometimes up to 15 dolphins are seen together. Traveling and staying in groups not only enables Irrawaddy dolphins to hunt, but it also creates and maintains social bonds and allows copulation to occur. There are a few groups of dolphins in Brunei Bay seen near the mouths of the Temburong and Aloh Besar rivers, which are tame and gather around fishermen's boats that catch fish during the fishing season from around December to February.
It surfaces in a rolling fashion and lifts its tail fluke clear of the water only for a deep dive. Deep dive times range from 30 to 150 seconds to 12 minutes. When 277 group dives were timed (time of disappearance of the last dolphin in the group to the emergence of the first dolphin in the group) in Laos, the mean duration was 115.3 seconds with a range of 19 seconds to 7.18 minutes.