Endangered British Mammals - Bottlenose Dolphin
Some of the largest Bottlenose dolphins (Tursiops truncatus) in the world live in the oceans surrounding the UK. They generally vary greatly in size, however, UK dolphins tend to be around a metre longer than those living off Florida in the USA. There are two types of the Bottlenose dolphin - those who live inshore are generally smaller and thinner and those who live offshore who are larger and fatter.
Dolphins in warmer, shallower waters tend to have a smaller body than their cousins in cooler pelagic waters.
For example, a survey of animals in the Moray Firth in Scotland, the worlds northernmost resident population, recorded an average adult length of just under 4 metres (13 feet). This compares with a 2.5 metres (8 feet) average in a population of Florida. Those in colder waters also have a fattier composition and blood more suited to deep-diving. Bottlenose dolphins are easily recognisable by their dark and curved-back dorsal fin on their grey bodies.
Every 5 - 8 minutes, the Bottlenose Dolphin, like all other dolphins, needs to rise to the surface to breathe through its blowhole, though it generally breathes more frequently - up to several times per minute.
Bottlenose Dolphins live in social groups called 'Schools' or 'Pods' containing up to 12 individuals. These are long-term social units. Typically, a group of females and their young live together in a pod and juveniles in a mixed pod. Several of these pods can join together to form larger groups of one hundred dolphins or more. Male Bottlenose Dolphins live mostly alone or in groups of 2 - 3 and join the pods for short periods of time.
Bottlenose Dolphins have between 40 and 52 teeth in their upper jaw and 36 - 48 teeth in their lower jaw. Their diet consists mainly of small fish, occasionally squid, crabs, octopus and other similar animals. Bottlenose Dolphins feed on around 8 - 15 kilograms of food per day.
The gestation period of the female Bottlenose Dolphin is 12 months. Calves are born in midsummer in European waters and between February and May in Florida. They are born in shallow water, sometimes assisted by a 'midwife' (which may be a male Bottlenose Dolphin). The new single calf measures about 1 metre (3 feet) long at birth.
Although still generally plentiful, Bottlenose Dolphins have been virtually wiped out in some places. Bottlenose Dolphins are hunted for meat and other products in parts of the world.
In the Pacific, Bottlenose Dolphins are often drowned in tuna nets, although new 'dolphin-friendly' nets are now being used more widely. There have also been concerns about man-made marine noises such as shipping sonar. These noises upset whales and dolphins and affect their ability to feed, navigate and communicate. Evidence suggests that military submarine detection systems producing Low Frequency Active Sonar, floods the oceans with noise and threatens the survival of whales and dolphins by destroying their hearing and causing their ears and lungs to haemorrhage. (You can also see Bottlenose Dolphins in our Marine section).
Endangered British Mammals -
Bottlenose dolphin |
European Hare |
Hazel Dormouse |
European Otter |
Greater Horseshoe Bat |
Greater Mouse-eared Bat |
Harbour Porpoise |
Red Squirrel |