It’s National Dolphin Day! Some of us remember the 60’s and the hit TV show Flipper. The story was about Ranger Porter Ricks who was responsible for the animal and human life in Coral Key Park, Florida, and centered around his 15-year-old son Sandy and 10-year-old son Bud, and especially on their pet dolphin Flipper. In the show it showed how charismatic dolphins are loved for their playfulness and agility. They are social, intelligent, and captivating to watch as they leap through the water. Dolphins are mammals, just like us, and they are also in the same family as whales.

Dolphins are found all over the world, mostly in salt water – but some do live in fresh water. There are about 40 different species of dolphins, ranging in color and size. Some dolphins can be as large as 30 feet! Because dolphins are social animals, they travel in packs of 5 to 700. Dolphins communicate with each other using special sounds and whistles.

Bottlenose dolphins ( Tursiops truncatus ) have elaborate sound production and receiving systems. In the Tursiops, four major types of vocalisations have been identified: whistles, clicks, burst pulsed sounds and chirps.

Whistles are used in communication.  In the larynx, dolphins can produce high-pitched whistles and squeals which can rapidly change pitch. Whistles are single tones, with no vibrations that make them sound like buzzes. As far as scientists can tell, the whistles are a form of communication with other dolphins, and squeals are used to express alarm or sexual excitement. They are continuos, narrow-band, frequency-modulated pure tones, limited in frequency to the mid- and upper- range of the sonic spectrum, generally from 4 to 24 kHz, and a half a second in duration. 

Clicks are directional and used for echolocation. These are short, broad-band pulses ranging from .2 to 150 kHz.   Dolphins are able to click and whistle at the same time. Echolocation sounds are produced in their nasal passages just below their blowholes, and are called clicks. Clicks are sometimes produced in such rapid succession that they sound like buzzes or even quacks, and beamed forward from the dolphin’s head. These sounds are produced just behind the melon, an oily, slightly off-center lump on what you’d call the dolphin’s forehead, and the sound waves are focused forward through it. Scientists are not entirely certain how the melon works, but it does seem to amplify and clarify the dolphin’s echolocation sounds, and may play a part in collecting the sounds bouncing back. They allow a dolphin to detect remarkably detailed information from the world around them. In one test, a dolphin found a marble-sized sphere at more than the length of a football field. Some scientists speculate that echolocation sounds may also be used to deliver an acoustic shock to small prey.

Burst pulsed sounds occur commonly in social and emotional context and are thought to be used for communication. These are trains of clicks with repetition rates of up to 5000 clicks per second. The high repetition rate gives a tonal quality to the sounds.

Chirps are thought to be used in communication. These sounds are pulsed, frequency-modulated, broad-band sounds. Frequency modulation occurs in different frequency bands.

Here are 8 special things that you might not know about dolphins:

Killer whales are dolphins
Dolphins and whales are closely related – both are in the order Cetacea, which includes whales, dolphins, and porpoises.  Orcas were given the name “killer whale” by ancient sailors’ observations of groups of orcas hunting and preying on larger whale species.

 

Dolphins are born tail first
Being a mammal and giving birth at sea is no mean feat, and every baby dolphin comes into the world in reverse. If you’re lucky enough to see a very young dolphin you might also notice that they look ‘creased’ from where they were folded up inside their mothers.

Scottish dolphins?
Yes, Scottish bottlenose dolphins are the biggest in the world.  Scottish dolphins are also pretty easy to see from shore, or on a boat trip, and support a thriving ecotourism industry in the Moray Firth.

Some dolphins live in the trees
Not all dolphins live in the sea, with a handful of species preferring freshwater and living in tropical rivers. That means that in the flooded waters of the amazon, river dolphins swim amongst the trees.

Dolphins have central heating & cooling systems
Because they are covered in a blubbery coating to stay warm, dolphins have to take special measures to regulate their temperature. They use their circulation to cool down blood in their fins and send it where staying cool matters most.

Dolphins call each other names
Scientists have discovered that complex dolphin communication includes referring to each other by a given ‘name’.

Not all dolphins look the same
There are about 40 species of dolphins: some have no beak, some have no fin on their back, some are black and white, some are pink, some have go-faster stripes, and some are covered in scars. The one thing they do have in common is conical shaped teeth that are perfect for catching fish and squid on the move.

Celebrate National Dolphin Day by going to a beach or on a boat ride to see some dolphins. If you don’t live near a spot populated with dolphins, don’t worry! There are tons of fascinating online videos you can watch instead.