Dolphins and whales belong to the order Cetacea. The order Cetacea is broken down into two different groups or sub orders – baleen whales (Mysticeti) and toothed whales (Odontoceti). Dolphins are small toothed whales (Odontocetes) and belong to the family Delphinidae. There are approximately 30 species within this family.
The Koombana Bay dolphins are Bottlenose dolphins (Tursiops truncatus). They have beaks that are short, usually only 7-8 cm long, wide and rounded, with a lower jaw which protrudes conspicuously beyond the upper. The line of the mouth is soft and curves upwards at the back to give this species its familiar, faintly amused facial expression.
Bottlenose dolphins can stay underwater for 8-10 minutes, however the average “down time” is 2 or 3 minutes. When a dolphin dives the blowhole shuts completely, otherwise their lungs would fill with water and they would drown.
Did you know?
- Bottlenose dolphins, like all whales and dolphins, are warm blooded mammals. They breathe air and the females give birth to live young.
- The Gestation period for a female is 12 months and she will nurse her calf for 2-3 years. The mother will always wean her calf before giving birth to another, therefore she is able to calve every 3-4 years.
- Calves weigh approximately 30 kgs at birth (0.5 to 0.9 metres in length) and can grow to seven times their body weight in the first year. This is possible due to the very fatty milk fed by their mother.
- The weight of Bottlenose dolphins will vary from 110 kilos to 400 kilos. Their length can range from 1.5 to 4 metres.
- It is estimated that wild Bottlenose dolphins can live for 35-45 years. This is longer than the previously thought 25-35 years. However life expectancy of dolphins is hard to measure as they live so much of their lives out of human view.
- Dolphins are sexually active all year round, although mating season in Koombana Bay takes place in the spring and summer months.
- A female dolphin will mate with many different males. Males will compete aggressively for access to females that are sexually receptive (in oestrus).
- The best way to determine whether a dolphin is male or female is to look on the underside of the dolphin. The female has two mammary slits either side of her genital slit.