Welcome to the Marine Mili series, a regular column about all things marine! During this series I aim to inspire people to want to protect our oceans and all the marine life that call our oceans home. Hopefully after reading each column, you would have learnt something new including what we can do to help protect and preserve our oceans. You can follow me and my journey on my Instagram page: _marine_mili.
You might have read the title and thought ‘largest dolphin?’, that cannot be right as orcas are killer whales not killer dolphins.
In fact orcas are in fact the largest member of the dolphin family however, they are very closely related to whales. Whales, dolphins, and porpoises are all from the same family cetacean.
Orcas are apex predators which means they have no natural predators. However every now and again they are challenged by another predator, the great white shark who is also at the top of the food chain.
These intelligent cetaceans hunt in pods which gives them a better chance at catching prey. Orcas also use echolocation while hunting like other toothed whales including dolphins and sperm whales. In pods, orcas will send out sound waves that bounce of anything in their path, which gives them the exact location of their prey.
Male orcas can live for anywhere between 30-60 years while females can live between 50-90 years in the wild. Once females enter their 30s and 40s, they experience menopause, one of only three species on earth to experience menopause along with short-finned pilot whales and humans.
It is not always easy to identify if an animal from a certain species is a male or female. However with orca it is easy to determine their sex by just their dorsal fins.
Male orcas' fins can reach up to 1.8 metres in height, the largest dorsal fin of all cetaceans. Female orcas' dorsal fin ranges between 0.9-1.2 metres tall.
As the female's fins are significantly smaller this is a key way to identify them.
Most male orcas dorsal fins are very straight and point directly up to the sky, while female dorsal fins are more slanted backwards and look like the dorsal fin of a dolphin ... just much larger.
Individuals can also be identified by the nicks in their dorsal fins and the shape/colouration of their saddle patch.