Dolphin

Dolphin, any of the toothed whales belonging to the mammal family Delphinidae (oceanic dolphins) as well as the families Platanistidae and Iniidae, the two that contain the river dolphins. Of the nearly 40 species of dolphins in the Delphinidae, 6 are commonly called whales, including the killer whale and the pilot whales. The name dolphin is also applied to members of the fish genus Coryphaena (family Coryphaenidae).

Most dolphins are small, measuring less than 3 meters (10 feet) in length, and have spindle-shaped bodies, beaklike snouts (rostrums), and simple needle-like teeth. Some of these cetaceans are occasionally called porpoises, but scientists prefer to use this term as the common name for the six species in the family Phocoenidae, all of which differ from dolphins in having blunt snouts and spadelike teeth.

Dolphins are popularly noted for their grace, intelligence, playfulness, and friendliness to humans. The most widely recognized species are the common and bottlenose dolphins (Delphinus delphis and Tursiops truncatus, respectively). 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.

10 FACTS ABOUT DOLPHINS

1. DOLPHINS CAN BE FOUND ALL OVER THE WORLD AND IN DIFFERENT ENVIRONMENTS

2. FRESHWATER DOLPHINS

3. UNDERWATER NOISE POLLUTION IS A REAL THREAT TO DOLPHINS

4. THEY’RE FAST SPRINTERS

5. HOW DO YOU EAT FISH?

    Probably not the same as a bottlenose dolphin, that’s for sure! They swallow a        fish head first so the fish's spines don't catch in their throat. 

6. THEY LIKE TO BLOW BUBBLES

7. DOLPHINS ARE CHATTY ANIMALS

8. THEY’RE INTELLIGENT, LIKE US

9. THEY CAN TURN OFF HALF OF THEIR BRAIN

10. FISHING GEAR IS A MAJOR THREAT TO DOLPHINS

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 a 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 Araguaia 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 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 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 the reality: not all of these animals live in the sea, and not all look like the bottlenose dolphin that most people know. There are also dolphins that inhabit 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.