Bottlenose Dolphins

Bottlenose dolphins are the stars of the show at A Bay to Remember and the characters that make Cardigan Bay in West Wales the top location in the UK – and Europe! – for dolphin watching.

Bottlenose dolphins are members of a family of marine mammals called the cetaceans (seh-TAY-shunz), which also includes porpoises and whales. They are large animals, growing to an average length of 3.1 to 3.7 metres (10 – 12 feet) and weighing up to 650kg. The markings of the bottlenose dolphins are quite subtle, having a brownish-grey upper body with a contrasting paler underside. This pattern is known as countershading. It is a form of camouflage that makes them more difficult to spot against the deeper water beneath them and against the lighter surface when looking up through the water. This helps to protect them against predators and gives them an advantage when hunting as well.

Like all mammals, dolphins breathe air and have a single nostril-like blow hole on the top of their heads that they close when they are under the sea surface. The beautiful arching leaps out of the water that bottlenose dolphins are renowned for are thought to help with breathing when they are travelling at speed through the water – up to 20 miles an hour on average. They can hold their breath for a long time, though, and can stay under water for around 10 minutes. This is because they can absorb up to 10% of the oxygen they breathe in from the air – compared to the 4% that we and other land mammals absorb.

Dolphins propel themselves through the water using their strong tails that move up and down, unlike fish that move their tails from side to side to swim. Their flippers control their direction while their characteristic dorsal fins provide stability in the water. Those dorsal fins are highly individual, almost like a fingerprint, and they help researchers to identify individuals for study. Your skipper might recognise some local characters on your boat trip!

Dolphins have a fat-filled cavity in their heads called a melon that is used to help them to “see with sound”!  They use the melon to project a series of clicks forward that then bounce back off objects such as obstacles and prey. The “echoes” cause vibrations in their jawbone that are then picked up by the inner ear, providing vital information that helps the dolphins to navigate and hunt – this is called echolocation.

Highly social animals, bottlenose dolphins live in groups, known as pods, of up to 10 animals. They often hunt in packs, herding schools of fish close to the surface to be snapped up. Although dolphins have teeth, they don’t chew their food and swallow most of it whole! They mostly feed on schooling fish, bottom dwelling fish, and squid.

Female bottlenose dolphins start to breed at about 12 years of age. Of course, being mammals, they give birth to live babies and feed them a fat-rich milk for about 18 months, which helps them to rapidly build up the thick layer of blubber under their skin that helps to insulate them as they lack the hairy covering of most mammals. 

The young dolphins are born tail first so that they can swim straight to the surface for their first breath as soon as they are free from their mum. Another female “nurse” dolphin will often stay close to support the birthing mother and to help the new-born to the surface. Mother dolphins will also leave young calves with a “babysitter” when she needs to go hunting.  The females will go on to have a calf every 2-3 years. 

Dolphins can live for 40-50 years in the wild. Some of the animals that you might see could have been swimming in Cardigan Bay for longer than A Bay to Remember has been taking visitors to admire them!