Key points
- Dolphins are known for their grace and playfulness, but they are also incredibly intelligent and have fascinating natural talents.
- Dolphins are born with tiny moustaches which soon fall off, but the pits left behind can sense magnetic fields.
- Dolphins have fantastic hearing and memory when it comes to other dolphins, and can also recognise and inspect themselves in a mirror.
Dolphins are known for being graceful, intelligent, playful, social, and friendly.
They mainly feed on fish or cephalopods. But a few, like orcas (Orcinus orca), may also feed on larger mammals like seals and whales.
There are 19 species of dolphin recorded in Australian waters which all belong to the family of ocean dolphins, Delphinidae. However, some are only rare visitors or aren’t regularly spotted by humans.
The species you’re most likely to spot are the Indo-Pacific Bottlenose Dolphin (Tursiops aduncus), Common Bottlenose Dolphin (Tursiops truncatus), Australian Humpback Dolphin (Sousa sahulensis) and the Common Dolphin (Delphinus delphis).
Cetaceans are aquatic mammals which include whales, dolphins, and porpoises. There are six species of cetaceans commonly referred to as whales but which are actually dolphins! These are: orcas (killer whales), melon-headed whales, pygmy killer whales, false killer whales and two species of pilot whales.
Here are some fascinating facts that you might not know about dolphins.
1. You’ve gotta hair about dolphin moustaches!
Dolphins are mammals which give birth to live young. But another biological characteristic of mammals is that they all have hair.
But where, you may ask, do dolphins have hair? Well, if you moustache, it’s around their snout.
Dolphins are born with a few whiskers around their snout which most lose soon after.
Once the hairs fall out, they leave small pits in their snout called vibrissal crypts. Researchers have found that in the Guiana Dolphin (Sotalia guianensis) and the Common Bottlenose Dolphin, these vibrissal crypts are sensory receptors used in feeding. They detect electric fields, like those given off by small fish. This helps dolphins feed on prey they can’t find using their other senses.
Findings are not yet conclusive, but researchers think dolphins may even be able to sense the Earth’s magnetic field and therefore use it for navigation!
2. What is that I hear?
Like other toothed whales, dolphins use echolocation. This takes the form of short broad-spectrum burst-pulses that sound like "clicks" to humans. They use it to locate food and other objects in the ocean. However, the way that they hear sound isn’t as simple.
Dolphins don’t have external ears. They have small ear openings on both sides of their head, which they use to hear sound when they are above water.
There is no scientific consensus as to how dolphins hear underwater. The most popular theory is that their lower jawbone conducts sound to their inner ear.
Dolphins use sounds to communicate with each other and to locate things like prey. Where humans can only hear sound between 20 hertz and 20 kilohertz, some dolphins can hear sounds as high pitched as 150 kilohertz!
3. Mirror, mirror, on the wall, who's the fairest dolphin of all?
Common Bottlenose Dolphins are one of only a few animals able to recognise and inspect themselves in a mirror!
Dolphins encounter their own reflections more often than you might expect. The is because the water's surface acts as a mirror when they surface to breathe.
Researchers discovered that Common Bottlenose Dolphins, when temporarily marked with dye, exhibited fascinating behaviour in front of a mirror. They used the mirror to inspect that mark, recognising it as out of place.
4. Memory like an elephant
Within the first few months of their life, Common Bottlenose Dolphins invent their own specific call, called signature whistles.
They use this call to communicate with other dolphins throughout their life, like announcing their name.
They have a great memory for each other’s whistles. Researchers found Common Bottlenose Dolphins can recognise each other even 20 years after the last time they heard the call!
Researchers have also found Common Bottlenose Dolphins can recognise each other by the taste of their urine. Perhaps, wee shouldn't go into too much detail about that one.