Like other groups of animals, many dolphins are in danger of extinction. In most cases, the causes of the decline of dolphins come human beings Pollution, habitat destruction, accidental or conscious capture These are some of the reasons why these species have been disappearing for a long time.
In this article on our site we will talk about the dolphins in danger of extinction, we will learn about the types of dolphins that exist in the world and we will delve into the causes of its extinction or population deterioration.
How many dolphins are there in the world?
Currently, there are 41 known living species of dolphins, between oceanic dolphins and freshwater or river dolphins. Dolphins are aquatic mammals, therefore, they share characteristics with land mammals, such as:
- They have a highly developed brain: Like other mammals, dolphins have a complex nervous system. They have a high capacity for learning and memory. What sets them apart from other animals is how dolphins sleep. These have unihemispheric sleep, which in a nutshell means that they turn off one cerebral hemisphere so that it rests while the other remains active. Thanks to this, the dolphins can remain alert to the environment that surrounds them, they can breathe and continue swimming.
- Lung Breathing: Dolphins breathe through lungs. Through a hole, called a blowhole, on the top of their heads, dolphins take in air when they are on the surface. The spiracle connects directly with the trachea, which is shorter in these animals than in their terrestrial relatives. The trachea carries air through the bronchi to the lungs, which, unlike land mammals, are not lobed. Also, breathing is voluntary, it does not reflect, so you have to go actively to breathe.
- When they are born they have hair: one of the important characteristics of mammals is the presence throughout the body or in certain regions of hair. Adult dolphins do not have hair, this would be inconvenient for aquatic life. However, dolphins are born with a thin layer of hair that sheds as the animal grows.
- They are viviparous animals: Dolphins develop in the womb where there is a placental connection between the baby and the mother. After birth, the little dolphin will be totally dependent on its mother, who will have to help it to breathe on the surface. In addition, he will be fed breast milk for the first few months of life.
Types of dolphins
Dolphins are a relatively heterogeneous group of animals. They have common characteristics that allow them to live in the water but, morphologically, we can see differences between the different species, especially with the naked eye.
There are mainly two types of dolphins, although they all belong to the same parvorder (a taxonomic classification between order and family), the odontocetes These animals are characterized by having a multitude of teeth in a row, all equal to each other. The presence of these teeth reveals a carnivorous diet.
The group of Ocean dolphins is made up of 34 species:
- Tonina overa (Cephalorhynchus commersonii)
- Chilean Tonina (Cephalorhynchus eutropia)
- Heaviside's dolphin (Cephalorhynchus heavisidii)
- Hector's dolphin (Cephalorhynchus hectori)
- Coastal Common Dolphin (Delphinus capensis)
- Ocean common dolphin (Delphinus delphis)
- Pygmy killer whale (Feresa attenuata)
- Short-finned pilot whale (Globicephala macrorhynchus)
- Pilot pilot whale (Globicephala melas)
- Risso's dolphin (Grampus griseus)
- Fraser's dolphin (Lagenodelphis hosei)
- Atlantic dolphin (Lagenorhynchus acutus)
- White-beaked dolphin (Lagenorhynchus albirostris)
- Southern or Antarctic dolphin (Lagenorhynchus australis)
- Crossed dolphin (Lagenorhynchus cruciger)
- Pacific white-sided dolphin (Lagenorhynchus obliquidens)
- Fitzroy's dolphin (Lagenorhynchus obscurus)
- Northern Finless Dolphin (Lissodelphis borealis)
- Southern Finless Dolphin (Lissodelphis peronii)
- Irrawaddy river beluga dolphin (Orcaella brevirostris)
- Heinsohn's beluga dolphin (Orcaella heinsohni)
- Orca (Orcinus orca)
- Melon-headed dolphin (Peponocephala electra)
- False killer whale (Pseudorca crassidens)
- Tucuxi (Sotalia fluviatilis)
- Coastal (Sotalia guianensis)
- Hong Kong pink dolphin (Sousa chinensis)
- Atlantic humpback dolphin (Sousa teuszii)
- Tropical saddled or spotted dolphin (Stenella attenuata)
- Short-beaked spinner dolphin (Stenella clymene)
- Striped dolphin (Stenella coeruleoalba)
- Atlantic spotted dolphin (Stenella frontalis)
- Long-beaked spinner dolphin (Stenella longirostris)
- Narrow-beaked dolphin (Steno bredanensis)
- Indo-Pacific Dolphin (Tursiops aduncus)
- Burrunan dolphin (Tursiops australis)
- Bottlenose dolphin (Tursiops truncatus)
On the other hand, the river or river dolphins are divided into seven species and classified within the superfamily Platanistoidea:
- Amazon pink river dolphin (Inia geoffrensis)
- Bolivian dolphin (Inia boliviensis)
- River dolphin (Araguaia Inia araguaiaensis)
- Baiji (Lipotes vexillifer)
- Silver Dolphin (Pontoporia blainvillei)
- Ganges Dolphin (Platanista gangetica)
- Indus Dolphin (Platanista minor)
These animals are characterized by being practically blind and having a long and thin snout. Their limited vision is counteracted by the great capacity for echolocation that these animals have.
Endangered Dolphin Species
Probably, the list of endangered dolphins is much longer than the one shown. The problem is that there is hardly any data on these animals, they are difficult to see and study.
1. Hector's Dolphin
The Hector's dolphin (Cephalorhynchus hectori) is considered an endangered animal by the IUCN. In addition, some populations of this species are critically endangered.
two. Irrawaddy Dolphin
The Irawadi river dolphin (Orcaella brevirostris) is actually an oceanic dolphin, but it lives very close to the coast, and can often go up the estuary.
3. Pink Amazon River Dolphin
The Amazon river pink dolphin (Inia geoffrensis) not only inhabits this river, but also many of its tributaries. Like many species in the Amazon rainforest, this dolphin is also in danger of extinction.
4. Ganges Dolphin
The Ganges dolphin (Platanista gangetica), is considered endangered in the Ganges River area. However, it seems to be present in other rivers, albeit equally polluted.
5. Indus Dolphin
The Indus dolphin (Platanista minor) is a species considered in danger of extinction, for the same reasons as other river dolphins.
6. The Biji
It is not known for sure, but it is very likely that the Baiji (Lipotes vexillifer) is completely extinct. Even so, the IUCN considers it a critically endangered species.
Why are dolphins endangered?
According to the trend, these now endangered species are likely to extinct in the coming years The main The problem of oceanic dolphins is the gillnets Dolphins easily get caught in this type of net, which is prohibited in some countries.
These nets can also cause the loss of their swimming limbs. Entanglement with these nets is the assured death for these animals. But in addition, the pollution of the oceans and the overfishing negatively affect dolphin populations They have less and less food available.
The causes of extinction of river dolphins are always the construction of dams In the regions where these animals live, they have been built in the last decades more than 100 dams. In addition, the establishment of certain companies on the banks of the rivers polluted them in such a way that their recovery is now impossible or very unlikely.
Discover also on our site 10 curiosities about dolphins based on scientific studies.
What to do if I find a stranded dolphin?
For reasons that are still being studied, more and more dolphins are stranded on the coast. Most of these animals already beach when they are practically dead, but many others still have chances of surviving.
In regions where dolphins usually beach, there are specialized recovery centers where you can call if you come across one. In other places, these centers do not exist, so what we have to do is call emergencies and, meanwhile, maintain hydrated the animal, pouring little by little sea water over its skin.
We should never try to return a stranded dolphin to the sea, this must be determined by a specialized veterinarian. On the other hand, we must avoid people crowding around These animals are not used to being touched, so we could increase their stress and accelerate death. One person keeping it hydrated while specialized services arrive is enough.
To finish we show you the video of a rescue of a stranded dolphin: