Generally, bottlenose dolphins are dark bluish-grey or brownish-grey on top with a lighter belly. They have quite chunky bodies and a thick tail stock.
Of all the species of dolphin, bottlenoses show the biggest range in size between individuals. Some adults can be almost double the length of others! It's quite possible for two to be a very different size, shape and colour from one another, even if they live in the same school, so if they come from separate populations, they are likely to be even more different.
The Scottish dolphins are some of the world's largest dolphins and can be a good metre longer than those living off Florida in the USA for example. They are also generally fatter than other bottlenoses, probably because it can get so cold, particularly during Scottish winters.
The easiest way of recognising a bottlenose is to look out for an obvious dark and curved-back dorsal fin on a lively grey dolphin! They can, however, quite easily be confused with other dolphins such as spotted and humpback dolphins. The shape of their dorsal fin, along with nicks, scratches and other markings on their skin, are what researchers use to identify individual bottlenose dolphins.
As with length, bottlenoses can be very different weights especially depending on where they live. Some of them are more than four times as heavy as others! Adults can weigh between 150 and 650 kg (330 - 1435 lb) and new-borns between
15 and 30 kg (35 - 65 lb).
Sexual maturity
Female bottlenose dolphins can become sexually mature as young as 5 years old, although most don't become mature until they are around 11 or 12. There may be problems during the pregnancy if they conceive when they are too young and not fully grown. An older female will also be more experienced and this should benefit her calf. Males become sexually mature between the ages of about 9 and 13 years old.
Males and Females
It can be difficult to a tell a male from a female dolphin, even when it is fully grown, without being able to closely examine its underside. This is because the sexes can be the same size, shape and colour and also behave in similar ways. Females are easy to spot once they have had a calf because the youngster will be seen sticking closely to her side for several years.
Number of calves
Bottlenose dolphins are quite slow breeders and females usually only have a calf every three to five years. They also give birth to just one baby at a time; dolphin twins are very, very rare, and sadly normally die either before birth or soon after being born.
Mating
Dolphins don't stay with the same partner for life and, in fact, males don't play any part in helping to raise calves. Dolphins are promiscuous animals and spend a lot of their time in sexual play with almost any other member of the group. When they do mate, dolphins do so belly to belly. |
