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They may not be on Facebook, but dolphins have complex networks of friends much like humans, scientists claim.

A new study reveals that bottlenose dolphins avoid individuals they don't like and hang out with their friends in specific parts of a lagoon.

Experts found that the geography of the lagoon they studied on the Atlantic Coast of Florida seemed to influence the social dynamics of the group too.

A new study reveals that bottlenose dolphins avoid individuals they don't like and hang out with their friends in specific parts of the Indian River Lagoon in Florida (pictured)

Scientists at the Harbor Branch Oceanographic Institute (HBOI) at Florida Atlantic University, studied interactions between 200 dolphins in the Indian River Lagoon to reveal how they mingle.

While it's well known that dolphins are social animals, the team carried out photo ID studies over six-and-a-half years, to learn about the movement behaviour and habitat preferences of the dolphins.

They found that just like humans, individual dolphins spent time with individuals they liked and avoided those they didn't. 

Scientists at the Harbor Branch Oceanographic Institute (HBOI) at Florida Atlantic University, studied interactions between 200 dolphins in the Indian River Lagoon (mapped)  to reveal how they mingle

 They found that just like humans, individual dolphins spent time with individuals they liked (illustrated in this stock image) and avoided those they didn't

Dolphins also clustered into groups of friends and tended to occupy core areas along the north-south axis of the lagoon system.

Those that gathered in narrow areas had the tightest group of friends. 

The lagoon is 156 miles (251 km) long and is composed of three bodies of water, including the Indian River, with five inlets connecting it to the Atlantic Ocean.

It ranges in width from 10 feet (3 metres) to five miles (9km) and has an average depth of four feet (1.5metres). It's 13 ft (4metres) at its deepest point.

'One of the unique aspects of our study was the discovery that the physical dimensions of the habitat - the long, narrow lagoon system itself - influenced the spatial and temporal dynamics of dolphin association patterns,' Elizabeth Murdoch Titcomb, research biologist at HBOI explained.

'For example, communities that occupy the narrowest stretches of the Indian River Lagoon have the most compact social networks, similar to humans who live in small towns and have fewer people with whom to interact.'

While it's well known that dolphins are social animals, the team carried out photo ID studies over six-and-a-half years, to learn about the movement behaviour and habitat preferences of 200 individual dolphins. This is one of the photos they took

It's hoped this information will be used by resource managers to help them understand how dolphins use their environment, as well as how social networks transfer information, breeding behaviour and even diseases. This image shows researchers identifying individuals they are studying

The study, published in the journal Marine Mammal Science, offers an important insight into how dolphins organise themselves, who they interact with and who they avoid.

It's hoped this information will be used by resource managers to help them understand how dolphins use their environment, as well as how social networks transfer information, breeding behaviour and even diseases.

In 1990, the Indian River Lagoon was declared an 'estuary of national significance' by the US Environmental protection Agency, because it's one of the most biodiverse estuaries in North America.

Researchers from HBOI have been conducting photo identification studies of bottlenose dolphins in the lagoon since 1996 and have identified more than 1,700 individual dolphins.

WHY DOLPHINS ARE EXCELLENT COMMUNICATORS 

Wild dolphins around Africa have recently been found to have distinctive whistles, called signature whistles. A stock image is shown

Wild dolphins around Africa have recently been found to have distinctive whistles, called signature whistles.

They are exchanged by groups of dolphins when they meet at sea and are used to address each other, in a similar way to how humans use names.

In 2010, Italian scientists revealed that bottlenose dolphins use short vocal bursts to communicate messages that avoid conflict in times of high excitement or aggression, such as while hunting.

'Burst-pulsed sounds are used in the life of bottlenose dolphins to socialise and maintain their position in the social hierarchy in order to prevent physical conflict, and this also represents a significant energy saving,' said study leader Dr Bruno Diaz, from the Bottlenose Dolphin Research Institute in Sardinia.

Whistles are used by dolphins to stay in contact with each other and co-ordinate hunting strategies.

The 'burst-pulsed' sounds are more complex and varied. They are produced when dolphins are in close proximity to other individuals moving towards the same prey, the Italian scientists discovered.

Last year, dolphin expert and founder of the Wild Dolphin Project, Dr Denise Herzing, claimed she heard one of the creatures 'say' the word sargassum - a type of seaweed - when she was swimming in the Caribbean in August 2013.

She used a prototype dolphin translator called Cetacean Hearing and Telemetry (Chat) to translate the whistle.

The machine detected a whistling sound for sargassum, which Dr Herzing had invented when she was playing with the dolphin pod that she has studied for the last 25 years.

Her team hoped the animals would continue to use the whistles, which are quite different to the noises they naturally make.

When the dolphin 'said' sargassum, Dr Herzing heard her own voice because the machine translated the unique whistle as 'sargassum'.

It is not known whether the dolphin 'said' the word because it saw some of the seaweed and was trying to communicate with another a dolphin.

So far the sargassum whistle has been heard just once.