Facts About Dolphins

About Dolphins:

Dolphins are incredible. They are socially skilled, intelligent, agile, joyful, and playful creatures that share many emotional similarities with humans. There is an impressive range of different species of dolphin and they all have their own unique identities and characteristics. Dolphins are popularly noted for their grace, intelligence, playfulness, and friendliness to humans. The most widely recognized species are the common and bottlenose dolphins. The bottlenose, characterized by a “built-in smile” formed by the curvature of its mouth, has become a familiar performer in oceanariums. It has also become the subject of scientific studies because of its intelligence and ability to communicate by using a range of sounds and ultrasonic pulses. It adapts to captivity better than the common dolphin, which is timid. In addition, the bottlenose dolphin has the longest social memory of any nonhuman species; several members of the species were able to recognize the unique whistles of individual dolphins they once associated with at least 20 years after becoming separated from them. Bottlenose dolphins have demonstrated the ability to recognize their reflections in several experiments, suggesting a degree of self-awareness. That capability has been observed only in higher primates and a few other animal species.



Natural history

Dolphins can live in either fresh or salt water. Distributed in marine environments worldwide, they range from equatorial to subpolar waters and also can be found in many major river systems. The common and bottlenose dolphins are widely distributed in warm and temperate seas. They are swift swimmers; the bottlenose can attain speeds of nearly 30 km/hr (18.5 mph) in short bursts, and common dolphins are even faster. A number of species are attracted by moving ships and often accompany them, leaping alongside and sometimes riding the waves created by the ships’ bows. Some coastal species of oceanic dolphins spend considerable amounts of time in fresh water. Most river dolphins live in fresh water that may be several thousand kilometers from the sea, although some spend their lives in coastal waters. Dolphins are social, gathering in schools from five to several thousand. All are carnivorous, feeding on fish, squid, and other invertebrates.


Conservation status

Information regarding current population levels and trends remains elusive for many dolphin species. Although bottlenose dolphins are species of least concern, according to the International Union for Conservation of Nature (IUCN), several dolphins are at risk of extinction. Dolphin species that the IUCN considers vulnerable or near threatened include the Indo-Pacific humpbacked dolphin (Sousa chinensis), the Irrawaddy dolphin (Orcaella brevirostris), and the Australian snubfin dolphin (O. heinsohni). The most vulnerable dolphins include the Ganges river dolphin (Platanista gangetica) and the Indus river dolphin, which are classified as endangered species, and the Atlantic humpbacked dolphin (Sousa teuszii), which is classified as critically endangered.



Types of Dolphins

There is not an absolute number of extant dolphin species to date. Moreover, the studies continuously carried out on these cetaceans still find the existence of more species occasionally, either because of new discoveries or because the scientific classification of a species seems not entirely correct as result of applying new technologies like genetic research.

There is not a formal taxonomic classification of dolphins. They are an informal group formed by the 39 species of the family Delphinidae of oceanic dolphins plus the five* species of the superfamily Platanistoidea of river dolphins. Recently the Araguaian river dolphin was split from the amazon river dolphin and was added to this family, and the Baiji is functionally extinct but still considered in this list. You should know that dolphins are mammals related to whales, but unlike them, they have teeth. Whales and dolphins are cetaceans, that is, animals, that belong to the taxonomic order Cetacea, a group of mammals fully adapted to the aquatic life. This order, in turn, is divided into two suborders: Mysticeti and Odontoceti. Whales are members of the former suborder while dolphins belong to the latter, although this classification also includes porpoises, beaked whales, and sperm whales.


The parvorder Mysticeti includes all the baleen whales, which are cetaceans that have a fibrous structure useful for filtering the food. Odontoceti has teeth, instead of those baleen plates. The curious thing is that dolphins, toothed cetaceans, do not use their teeth to tear the flesh of their prey like sharks but to hold their food and for other purposes related to their senses and communication.

There are 39 species of oceanic dolphins classified in 17 Genus, and five species of river dolphins classified in 4 Genus, but these numbers keep changing with new discoveries.

For practical purposes, there are around 44 species of dolphins classified in 21 Genus, but again, these figures may change with time. The image that many people have of dolphins may be a little different from reality: not all of these animals live in the sea, and not all look as the bottlenose dolphin that most people know. There are also dolphins that inhabit in freshwater rivers, although their distribution is rather small and less known. These freshwater cetaceans are also considered Dolphins even though they do not belong to the family Delphinidae of oceanic dolphins.


                                                                  


Species Of Dolphins


Dolphin species according to 

their taxonomic classification :

Order: Cetacea
Suborder: Odontoceti Dolphins
Family: Delphinidae

Genus: Delphinus



1- Delphinus capensis (Long-breaked common dolphin)
2- Delphinus delphis (Short-breaked common dolphin)
3- Delphinus tropicalis. (Arabian common dolphin)

  -Genus: Tursiops
4- Tursiops truncates (Common bottlenose dolphin)
5- Tursiops aduncus (Indo-Pacific bottlenose dolphin)
6- Tursiops australis (Burrunan dolphin)

  -Genus: Lissodelphis
7- Lissodelphis borealis (Northern right whale dolphin)
8- Lissodelphis peronii (Southern right whale dolphin)

  -Genus: Sotalia
9- Sotalia fluviatilis (Tucuxi)

10- Sotalia guianensis (Guiana dolphin)

    -Genus: Sousa
11- Sousa chinensis. (Indo-Pacific humpback dolphin)
Subspecies:
– Sousa chinensis chinensis (Chinese white dolphin)
– Sousa chinensis plumbea. (Indo-Pacific humpback dolphin)
12- Sousa teuszii (Atlantic Humpback Dolphin)
13- Sousa plumbea (Indian Humpback dolphin)

   -Genus: Stenella
14- Stenella frontalis (Atlantic spotted dolphin)
15- Stenella clymene (Clymene dolphin)
16- Stenella attenuate (Pantropical spotted dolphin)
17- Stenella longirostris (Spinner dolphin)
18- Stenella coeruleoalba (Striped dolphin)

    -Genus: Steno
19- Steno bredanensis (Roug-toothed dolphin)

    -Genus: Cephalorhynchus
20- Cephalorhynchus eutropia (Chilean dolphin)
21- Cephalorhynchus commersonii (Commerson’s dolphin)
22- Cephalorhynchus heavisidii (Heaviside’s Dolphin)
23- Cephalorhynchus hectori (Hector’s dolphin)

    -Genus: Grampus
24- Grampus griseus (Risso’s dolphin)

   -Genus: Lagenodelphis
25- Lagenodelphis hosei (Fraser’s dolphin)

   -Genus: Lagenorhynchus
26- Lagenorhynchus acutus (Atlantic white-sided dolphin)
27- Lagenorhynchus obscurus (Dusky dolphin)
28- Lagenorhynchus cruciger (Hourglass dolphin)
29- Lagenorhynchus obliquidens (Pacific white-sided dolphin)
30- Lagenorhynchus australis (Peale’s dolphin)
31- Lagenorhynchus albirostris (White-breaked dolphin)

   -Genus: Peponocephala
32- Peponocephala electra (Melon-headed whale)

  -Genus: Orcaella
33- Orcaella heinsohni (Australian snubfin dolphin)
34- Orcaella brevirostris (Irrawaddy dolphin)

  -Genus: Orcinus
35- Orcinus orca (Orca- Killer Whale)

  -Genus: Feresa
36- Feresa attenuate (Pygmy killer whale)

  -Genus: Pseudorca
37- Pseudorca crassidens (False killer whale)

  -Genus: Globicephala
38- Globicephala melas (Long-finned pilot whale)
39- Globicephala macrorhynchus (Short-finned pilot whale)

Superfamily: Platanistoidea

  -Genus: Inia
Family: Iniidae
40- Inia geoffrensis (Amazon river dolphin)
41- Inia araguaiaensis (Araguaian river dolphin)

  -Genus: Lipotes
Family: Lipotidae
42- Lipotes vexillifer (Baiji)

-Genus: Pontoporia
Family: Pontoporiidae
43- Pontoporia blainvillei (La Plata dolphin) 

-Genus Platanista
Family: Platanistidae
44- Platanista gangetica. (South Asian river dolphin)
Subspecies:
– Platanista gangetica gangetica (Ganges river dolphin)
– Platanista gangetica minor (Indus river dolphin)


Threats

For centuries, people have hunted dolphins for their meat and blubber. Today, their main threat comes from being caught accidentally in commercial fishing nets. Dolphins must rise regularly to the surface to breathe—becoming entangled in nets prevents this, leading to drowning. For marine dolphins, warming ocean temperatures because of climate change have caused some of their primary food sources to move into deeper, cooler water. Furthermore, marine heatwaves, also caused by climate change, appear to have a negative effect on dolphins' reproductive rates and ability to survive.


References Links

  • https://uk.whales.org/whales-dolphins/facts-about-dolphins/

  • https://www.britannica.com/animal/dolphin-mammal

  • https://www.dolphins-world.com/

  • https://www.nationalgeographic.com/animals/mammals/facts/dolphins
  • https://www.pexels.com/search/dolphin/
















































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