The Irrawaddy dolphin (aka the Mekong or Mahakam River dolphin) can be found swimming in parts of the Bay of Bengal, Southeast Asia, Philippines and Papua New Guinea.
Generally a slow-moving species of dolphin they can reach speeds of up to 25 miles per hour when threatened or startled and while they aren’t known for being particularly acrobatic they have been spotted occasionally leaping out of the water.
Not much is known about the hunting methods of the Irrawaddy dolphin but it is known that their diet consists of fish, cephalopods, crustaceans and fish eggs.
Physical Characteristics and Appearance
In terms of appearance they share features that are visually similar to the beluga whale although they are genetically closer related to the killer whale species.
These dolphins are a gray to dark blue color with a lighter colored stomach and front.
They have a large forehead and rounded skull which lacks the appearance of a snout or beak.
The dorsal fin is rounded and located around the middle of its back.
They also have long-broad flippers.
In terms of size these dolphins can weigh up to 300 pounds and grow to 7 – 8 ft. in length on average.
Social Structure and Communication
These dolphins communicate using a series of clicks and buzzing sounds that allow these dolphins to talk to one another and determine which one in the group is communicating.
In most cases they prefer to travel in small pods consisting of 3 – 6 dolphins although their pod size may increase to include 15 or more dolphins on occasion.
While in their pods they remain social with one another and may occasionally intermingle with other pods.
These dolphins are not the type to bring attention to themselves as they are rarely seen splashing, rolling and slapping their fins against the water.
Other activities occasionally observed include spitting water, spy hopping and blowing bubbles.
Generally when in search of food they will dive for 1 – 2 minutes, however they have been observed holding their breath for up to 12 minutes (possibly longer) when necessary.
When they need to surface for air they keep a low profile only exposing the top of their head and their blowhole.
Mating and Reproduction
Not much is known about the breeding habits of these dolphins.
It is believed that mating season occurs from the beginning of the year through June.
Rough estimates also suggest that they reach sexual maturity between the ages of 4 – 9 where they can then begin mating and bearing offspring of their own.
The average gestation period (the period from conception to birth) is around 9 – 14 months.
Irrawaddy dolphins usually reproduce one offspring every 2 – 3 years.
Threats and Predators
Because these dolphins live closer to land than many other species of dolphin they are at a higher risk of being endangered by human activity.
The primary threats these dolphins face include pollution or water poisoning, collisions with boats and getting caught in fishing nets.
In fact drowning in fishing nets is considered one of the leading causes of death among this species.
Global warming, climate changes and the construction of dams are also believed to play a role in the endangerment of this species.
10 Thought-Provoking Irrawaddy Dolphin Facts
- The Irrawaddy dolphin is a marine mammal which means it’s warm-blooded, gives birth, produces milk (to feed its children) and breathes air.
- The Irrawaddy dolphin gets its name from the river that it is found swimming in, “the Irrawaddy river”.
- Although these dolphins look like a dark colored beluga whale in terms of appearance it is actually more closely related to the killer whale species, however it is not known for consuming other marine mammals.
- The scientific name for this marine mammal is, “Orcaella brevirostris”.
- The Irrawaddy dolphin is a protected species and hunting them could lead to steep fines and/or jail time.
- This marine mammal makes up one of 5 known river dolphins. The others include the Chinese river dolphin, Ganges river dolphin, Indus river dolphin and the franciscana (la plata) dolphin.
- Although the maximum amount of time these dolphins can hold their breath for is unknown the longest recorded dive lasted 6 minutes.
- The Irrawaddy dolphin uses echolocation to search for food and navigate the river at night and in dark environments.
- These marine mammals make up one of around 80 known species of cetacea (cetaceans include all species of whale, dolphin and porpoise).
- Due to their endangered status organizations such as the World Wildlife Foundation and Whale and Dolphin conservation society are working to shed light on the situation regarding the endangered status of these dolphins and a number of locations where these dolphins can be found such as Bangledesh, India, Malaysia and Thailand (among others) have placed strict laws prohibiting the killing/capturing of these marine mammals.