May
29
2017

Species Profile: The Common Bottlenose Dolphin

Common Bottlenose Dolphin Breaching Water (PD NASA/Wikimedia Commons)

 The Common Bottlenose Dolphin is probably the most recognizable dolphin species and it’s popular for its intelligence, friendliness and ‘smiling’ face.

This species of dolphin is one of the dolphin species in the family Delphinidae. Others include the the Indo-Pacific bottlenose dolphin and the Burrunan dolphin.

This dolphin is very well-known among humans because of its wide exposure in movies, documentaries, marine parks, etc. They are intelligent enough to spot large fishing boats and they will follow these boats for long seeking scraps of leftover fish.

It’s the largest species among beaked dolphins and it got the name bottlenose because of the shape of its snout that resembles an old-fashioned gin bottle. The body is smooth and grey in color, with a blowhole on top of the head. They breach the surface to breathe at least two or three times a minute.

They are social creatures that communicate with each other via a complex sequence of squeaks and whistles.

These dolphins inhabit temperate and tropical oceans all over the world except for polar waters.

1) Scientific Name

Tursiops truncatus

2) Scientific Classification:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Artiodactyla
  • Family: Delphinidae
  • Genus: Tursiops

3) Life Expectancy

40 to 50 years.

4) Average/Maximum Length

The common bottlenose dolphin averages between 2 and 4 meters (6.6 and 13.1 feet) long. Also, the males of this species tend to be larger and heavier than females.

5) Average/Maximum Weight

From 150 and 650 kg. (330 and 1,430 lbs.)

6) Maximum Swimming Speed

Bottlenose dolphins in general can reach speeds of up to 18 to 22 mph (29 to 35 km/h). It has a body shape that allows for very energy efficient swimming.

7) Interaction With Humans

Because of their intelligence and adeptness at learning complex tricks and skills, these dolphins feature in many human ventures.

  • Danger To Humans

Although the common bottlenose dolphin does not typically attack and kill humans, it has the potential to harm people because of its size and mass.

There have been instances where once friendly dolphins turn deadly. For instance, the story of the ‘killer dolphin’ Tião, though there was evidence that swimmers were pestering and harassing her.

Like with any wild animal, caution is advised.

However, it appears they are more at risk from people than the other way round. They are hunted on a commercial level in many countries especially Japan and the Faroe Islands. In addition, due to their wide distribution, they’re frequently killed as bycatch of tuna fisheries.

  • Intelligence

The Common Bottlenose dolphin has a larger brain than human beings. Like other dolphins, they are known for their remarkable intelligence and skills with things like mimicry, self-recognition, identifying and categorizing objects, etc.

They also use sound for communication. They emit squeaks (from their blowhole), whistles (from nasal sacs below the blowhole). Other forms of communication include body language, slapping their tails on water, and leaping high from water.

 The Common Bottlenose dolphin can breach up to 16 feet out of water and land with a huge splash.

K-Dog, trained by the US Navy to find mines and boobytraps underwater

K-Dog Has Been Trained By The US Navy To Find Mines And Boobytraps Underwater (PD US Navy/Wikimedia Commons)

As a result, they are used as ‘assistants’ in various human endeavors. For instance, they are used by the military in the U.S. Navy Marine Mammal Program were they are trained to locate sea mines or detect enemy divers. They also train them to search and rescue lost at sea naval swimmers.

In addition, in many regions, local fishermen train dolphins to drive large schools of fish towards their fishing nets. The fishermen make a good catch and the dolphins eat the fish that escape the nets.

8) Reproduction Details

Sexual maturity of this species varies by population and region but generally ranges from 5 to 14 years of age. Common bottlenose dolphins can breed throughout the year and will often choose multiple mates in a breeding cycle. They head-butt and tooth-scratch during courtship.

They reproduce through sexual copulation belly-to-belly and the gestation period is 12 months. Single births are most common but twin dolphins do occur from time to time. Their young are born live and are ready to swim and breathe shortly after birth.

Newborn calves weigh from 15 to 30 kg. (33 to 66 lbs.) and are between 0.8 and 1.4 meters (2.7 and 4.7 feet) long.

Calves remain with their mothers 8 years or less from the time of birth.

9) Diet/Hunting Pattern Of The Common Bottlenose Dolphin

Common bottlenose dolphins live in pods (groups) of about 15 individuals, though this could vary from just a couple to 100 or even 1000 individuals.

These groups may work as a team to harvest large schools of fish, though they can hunt successfully individually too. All dolphins search for prey using echolocation. This is a kind of sonar whereby they emit clicking sounds and interpret the resulting echo from nearby objects.

 Dolphin echolocation is fascinating, complex and extremely precise.

Their preferred diet is mainly eel, squid, shrimp and other kinds of fish. They don’t chew food but rather they swallow it whole.

10) Alternative names

  • Atlantic bottlenose dolphin
  • Bottlenose dolphin

11) Population And Conservation Status

Generally, specific hunting of dolphins for meat and oil has reduced considerably compared to previous times. Today, it is still hunted in few regions but the major threat is individuals getting entangled and caught as bycatch in commercial fishing nets.

Though the IUCN has assessed this species as Least Concern, it enjoys protection in some regions. For example, in The North Sea, Baltic, Mediterranean and Black Sea under the Convention on the Conservation of Migratory Species of Wild Animals (CMS) of the Bonn Convention.

It’s also protected in the North East Atlantic, Irish and North Seas and some parts of West Africa and Macaronesia.

12) Ancestry And History

The common bottlenose dolphin belongs to the genus Tursiops of the family Delphinidae, the oceanic dolphin.

Previously, it was assumed there was just one species in this genus but recent molecular studies showed that the genus contains three species. They are the common bottlenose (Tursiops truncatus), the Indo-Pacific bottlenose (Tursiops aduncus), and the Burrunan dolphin (Tursiops australis).

Studies are still ongoing as it appears that there are considerable genetic variation among members of this species. Hence, marine experts believe they may still find more species within this group.

13) Distribution And Habitat

Like others of this genus, they inhabit warm and temperate seas worldwide except the Arctic and Antarctic waters.

Some bottlenose populations prefer to live closer to the shore (inshore), while others live further offshore. Interestingly, offshore populations are larger and darker. They also have proportionally shorter fins and beaks.

Offshore populations move around more than inshore groups and can migrate up to 2,600 miles (4,200 km) in a given season.

These are caring animals and pods have been seen helping an injured dolphin get to the surface to breathe.

References:

1. http://www.nationalgeographic.com/animals/mammals/c/common-bottlenose-dolphin/

2. https://en.wikipedia.org/wiki/Bottlenose_dolphin

3. https://www.worldwildlife.org/species/common-bottlenose-dolphin

4. https://en.wikipedia.org/wiki/Ti%C3%A3o

Photo Credits:

https://en.wikipedia.org/wiki/Common_bottlenose_dolphin#/media/File:Tursiops_truncatus_01-cropped.jpg

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