Some authors consider Platanista minor to be a subspecies of Platanista gangetica, others consider them the same species, and others consider them distinct species. Genetic analysis has not yet answered the taxonomic mysteries of the Platanistdae family.
Indus River dolphins have extremely poor eyesight, perhaps since vision is nearly useless to navigate the murky rivers in which they live. They instead rely on echolocation to perceive their environment. Indeed, one of the common names for Platanista minor is “blind river dolphin”. Their external ears might help receive echolocation signals, which are intermittent pulses rather than continuous whistles. Though Indus River dolphins are very vocal, they use sounds for communication only about 5% of the time that they vocalize.
Communication Channels: acoustic
Perception Channels: tactile ; echolocation ; chemical
Platanista minor is a species of great concern, and a combination of human-created barriers such as dams and barrages, hunting, and a limited natural range have resulted in a dangerously-low total population of only several hundred individuals. These dolphins are classified as endangered, and have been so since the 1970's. Their extremely low population size may also restrict their gene pool, thus they might soon have many problems associated with low genetic variation within a population.
US Federal List: endangered
CITES: appendix i
IUCN Red List of Threatened Species: endangered
There are no known adverse affects of Platanista minor on humans, though no one knows what might happen to the river ecosystem if these highly-endangered animals eventually become extinct. At the very least, however, Pakistan will lose part of its biodiversity forever if the country does not take steps to protect this unique dolphin.
Some people hunt Indus River dolphins for their meat and oil. People in some areas eat the dolphin meat, while others use it as a fishing lure, though studies indicate that fish flesh is just as effective. The dolphin’s oil is used for medicinal purposes, its supposed effectiveness as an aphrodisiac, and to rub on one’s skin.
Positive Impacts: food ; source of medicine or drug
Indus River dolphins each eat about a kilogram of benthic fish and invertebrates daily, it is not clear how strongly they impact any of their prey populations.
Indus River dolphins use their echolocation abilities combined with their highly toothed, long snouts to forage for many bottom-dwelling animals including fish and invertebrates. Platanista minor has been known to eat some species of catfish, herring, carp, gobies, mahseers, prawns, and clams. Captive individuals reportedly consume about a kilogram of food each day.
Animal Foods: fish; mollusks; aquatic crustaceans; other marine invertebrates
Primary Diet: carnivore (Piscivore , Eats other marine invertebrates)
Indus River dolphins, Platanista minor, are found only in the Indus River in Pakistan. Platanista minor used to range throughout the river system, but the dolphins are now only found in the waters above the Kotri Barrage and below the Chasma, Trimmu, Sidhnai, and Islam Barrages. These human-created barriers, in addition to changes in rainfall patterns, have greatly limited the dolphins’ distribution.
Biogeographic Regions: oriental (Native )
Platanista minor currently exists only in the freshwater Indus River. However, some paleontologists believe that river dolphins might have evolved from marine-dwelling relatives that eventually moved to estuaries and then rivers as seawater levels rose and fell during the Miocene. Though this species prefers water deeper than 3 meters, Indus River dolphins have special adaptations such as swimming on their sides that enable them to exist in shallower waters as well. The temperature of the water ranges from 8-33 degrees C.
Range elevation: 0 to 250 m.
Range depth: 3 to 9 m.
Habitat Regions: freshwater
Aquatic Biomes: benthic ; rivers and streams; brackish water
No data is available about the lifespan of Platanista minor. The dolphins probably live for a long time since they are relatively large and require 10 years to reach sexual maturity. However, recent poor water quality and reduced habitat might affect the current longevity of these animals in the wild. At least a few Indus River dolphins have been kept in captivity, however, their longevity data is unavailable.
Average lifespan
Status: wild: 28.0 years.
Indus River dolphins are roughly the same color as the river, gray or brown, though they sometimes are lighter on their undersides. Their “beaks” are distinctively swollen at the tip and very long, reaching 20% of the length of their bodies, with large, visible teeth. In contrast to their “beaks”, their dorsal fins are rather small and reduced compared to other river dolphins. Large flippers and flukes, combined with long and remarkably flexible necks, probably help the dolphins navigate effectively. Platanista minor has external ears located below their eyes, but their eyes are very small and probably can only see shadowy, unclear images. Though Platanista minor and Platanista gangetica barely differ physically except for slight differences in tail lengths, the two species are distinguishable by their ranges. Platanista minor lives only in the Indus River system, while Platanista gangetica only inhabits the Ganges River system. Females are larger than males.
Average mass: 84 kg.
Range length: 2 to 2.5 m.
Sexual Dimorphism: female larger
Other Physical Features: endothermic ; bilateral symmetry
Platanista minor has few if any natural predators, however, they are often hunted by local people.
Known Predators:
These dolphins probably do not mate seasonally, since calves are born at different times throughout the year. However, in a captive population of two females and a male in Switzerland, the male reportedly chased the females in the spring. Though scattered captive populations of Platanista minor exist, little is known about the mating behavior of any of the members of the Platanistidae family.
Platanista minor breeds throughout the year, and has a very long gestation period of 8-11 months. Though not mentioned in the literature, this species probably only gives birth to one offspring at a time since newborns are about a meter long when they are born, which is nearly half the length of an adult female.
Breeding interval: Platanista minor probably does not breed more than once every two years or so due to such long gestation and nursing periods.
Breeding season: Mating occurs throughout the year.
Range gestation period: 8 to 11 months.
Range weaning age: 2 to 12 months.
Average age at sexual or reproductive maturity (female): 10 years.
Range age at sexual or reproductive maturity (male): 10 (low) years.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Little information is available about parental investment in Platanista minor, however, they most likely spend much time and energy on their offspring. Since females are pregnant for up to 11 months, newborns are about half the size of their mothers at birth, calves nurse up to a year after birth, Indus River dolphin offspring are probably very costly.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
News story on a study where elders were interviewed about the disappearance of dolphins along the river, showing the river flow below irrigation dams are having an effect on the dolphin's range.
Other names:Bhulan, Susu, Blind River Dolphin, Indus Susu
About:Indus dolphins are mammals, not fish. They come up to the surface for air, and as humans do, they give birth to live young, which feed on their mothers' milk. The Indus River dolphin is one of four river dolphin species and subspecies in the world that spend all their lives in freshwater.
Habitat:Found in silt laden turbid water, the Indus River dolphin once inhabited nearly the entire lower Indus River system. Currently, however, it is confined to the range highlighted on themap.
Weight:The Indus River dolphin weighs 70-110 kg (155 - 245 lbs).
Length:The maximum size is 2.5m (8.2 ft), with males smaller than females.
Colour:Mid gray-brown.
Eyes:The dolphin is functionally blind and has no lens in its tiny eye.
Teeth:Adults have between 30 and 36 sharp teeth on each side of the rostrum. The teeth are very long, protruding at the end of the rostrum.
Rostrum:River dolphins possess a much longer snout (rostrum) than most oceanic dolphins, up to one fifth of their body length.
Breathe:Dolphins breathe through a blowhole located on the top of their heads.
Neck:The neck is narrow and relatively flexible, easing its movements in the complicated river environment.
Flippers:The dolphin has very broad flippers to help it stabilise at slow swimming speed.
Reproduction:The gestation period for the dolphins is approximately 10 months and it is believed that the babies are born in spring. When a baby is born it is about 70 cm long (almost the length of a domestic cat and the mother helps it to the surface to breathe. Babies stay close to their mother for the first six months of their life.
Life span:Scientists think that these dolphins can live for approximately 20 years.
Diet:The Indus River dolphin eats crustaceans such as prawns, as well as fish such as gobies, catfish and carp.