Sri Lanka can now claim to be home to not one, but two of the world's biggest animals. Well-known for its free-roaming and working elephant populations, Sri Lanka can now boast of its own blue whale colony, the largest animals that have ever lived. (Yes, dinosaur fans, even bigger than the Argentinosaurus.)

Of course, they haven't just appeared overnight. For decades they went unnoticed by all but the most interested locals. Only within the last fifteen years or so have marine biologists begun to survey of the waters around this small island.

Unusually frequent sightings of this magnificent creature, at times when the whales should be moving from winter to summer feeding grounds, threw up many questions. Were they ill or hurt? Where they somehow trapped by shipping or oil-drilling activity? Happily, it is now believed that these whales are not merely passing through, en route to other waters, but actually live here year-round.

"How cool was this... to actually see blue whales. We had seven around the boats! I don't use 'awesome' but for this, I'll make an exception!"

So what do we know of this unique population? We know that they are the pygmy blue whale, Balaenoptera musculus brevicaudam, a little-known sub-species of blue whale. Reaching 24 metres when fully grown, about one and a half double-decker buses, they are the smallest of the blue whales. Their weight is estimated at 150 tonnes, though this is obviously hard to verify (whale-weigh station, anyone?).

Like all other baleen whales, they feed on tiny crustaceans, mainly krill, in the order of 40 million animals or 3.5 tonnes every day. Because krill move about, the whales dive to depths of 100 metres for around 10 minutes at a time, feeding on the surface only at night.

To feed, the whales rush, mouth agape, towards vast clouds of krill. Closing their mouths they push the water out through their baleen plates, trapping the krill behind. Despite their cavernous mouths, their throats are only as wide as a football.

Sri Lanka-born marine biologist Asha de Vos, has been studying these whales for the last decade and has made it her mission to learn more about these enigmatic giants. As non-migratory animals, they are reliant on a limited ecosystem, so a greater understanding could ultimately save the species.

Tell Tale Tip: Head to Mirissa on the southwest coast of Sri Lanka if you want to see the blue whales for yourself.

The sea around Sri Lanka is also an important breeding ground for other blue whales. With only around 10,000 blue whales left in the world, down from 360,000 before commercial whaling began in the 18th century, this is important work indeed. "I realised these guys in Sri Lanka were unique. If there are environmental threats, they can't leave in a hurry, so the risk to their survival is much higher," de Vos explains.

Since the realisation that the pygmy blue whale was living permanently offshore, whale watching trips have grown in popularity in Sri Lanka. Tell Tale Travel sends guests out with Mirissa Water Sports, a company set up after the tsunami to help provide employment opportunities for young people in the worst-affected coastal areas of Sri Lanka.

To see a blue whale is something of a privilege; they are generally very shy creatures and sightings are far from guaranteed on whale-watching excursions in other parts of the world. In Sri Lanka, however, it's rare that none are spotted – often you'll see several, along with spinner dolphins and rays.

Gary Baxter took a trip out with Mirissa Water Sports in January 2014 when he and his wife Susan travelled on our Leopards, Elephants, Peacocks and more itinerary: "How cool was this... to actually see blue whales off of the coast at Mirissa. We had seven whales around the boats! I don't use 'awesome' but for this, I'll make an exception!"

To learn more about the pygmy blue whales of Sri Lanka, watch Asha de Vos' video Saving Blue Whales or head to her blog for more in-depth information. Beware – you may have an uncontrollable urge to see these gargantuans for yourself.

Tell Tale Tip: See Sri Lanka's unique pygmy blue whales for yourself on any Tell Tale Travel holiday that takes in the historic town of Galle, including Elephants, Egrets and the Deep Blue Sea and Leopards, Elephants, Peacocks and more.