Australia is known for its unbelievable animals – both on land and in the sea. Marine mammals are creatures that mainly live and feed in sea water but, as they are still mammals, they breathe air just like us.
When it comes to marine mammals there is no doubt that ‘size matters’ since it helps with heat loss, oxygen capacity enabling longer dives, and energy efficiency. The Australian marine environment is home to some of the most extraordinary, largest, and unique species of marine mammals on the planet.
Australian fur seals are the largest seals in the world, reaching up to 2-3 meters long, and can stay at sea for weeks while feeding. They also have a very sophisticated two-layer coat of fur which allows them to always keep their skin dry. Like the fur seals, sea lions are also otariids (eared seals). They have peculiar, strong front flippers that give them an interesting and elegant standing posture, while also allowing them to both swim and walk on land.
There are also magnificent gentle giants that you can encounter all over Australia: the stunning humpback whale, southern right whale, dwarf minke whale and the immense blue whale. Do not let the name deceive you, even the ‘dwarf’ minke whale can be quite giant, reaching 5.5 meters in length!
It is not uncommon to see all these gigantic whales breaching, pectoral slapping, or slapping their tails with clumsy calves in tow, mimicking all the adults’ cool tricks. They are known for their unique way of communicating with each other, particularly the humpback whales, singing beautiful and complex songs allowing them to be heard kilometers from each other. It is a big ocean out there, with only sound enabling them to communicate across extensive distances.
Poll for your favourite marine mammal here.
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Continuing with the majestic marine mammal fauna of this continent there are a few coastal water inhabitants, including the humpback dolphins which live close to the coast within the tropical waters of Australia and Papua New Guinea. They typically are found in small groups near estuaries, deep channels, rocky reefs, in sheltered bays, open ocean and occasionally in surf zones.
They do what is called a ‘banana pose’ and put sponges on their head to attract mates, and in some areas they “strand feed” – beaching themselves to catch their food. Interestingly enough, these dolphins also seem to have a preference, always stranding on the same side. The first new dolphin to be described in more than 50 years is the snubfin dolphin, which has two stomachs like a cow and a strange-looking head lacking a rostrum (beak or snout), making them resemble belugas though they are quite distant cousins.
Lastly, let’s not forget about the incredible dugong, or sea cow, also found in Australian coastal waters. They are known as sea cows because they uproot seagrass using their strong, clefted upper lips. Despite their appearance, they are actually more closely related to elephants than whales or dolphins.
All these fascinating creatures have been through many impressive adaptations that led them to reconquer the marine environment and prevail not only as inhabitants, but as sentinel species and great predators of the sea, making them the most extraordinary mammals on this Earth. The end.
The nominees for most loved marine mammal are:
Australian fur seal (Arctocephalus pusillus), southern Australian coast including SA, VIC, NSW and Tasmania
Their streamlined shape and long flippers mean the Australian fur seal is an incredibly agile swimmer that can dive to depths of 200 metres to catch fish and squid.
Australian snubfin dolphin (Orcaella heinsohni), tropical coastal waters of northern Australia including WA, NT and QLD
Snubfin dolphins have vertebrae that make them able to flex their necks, unlike most other dolphins and whales. Because of this, they can surface and take a breath without showing their dorsal fin.
Killer whale (Orcinus orca), all coasts
Also known as Orca, these are some of the most efficient large predators in the ocean. They work cooperatively in packs to take on a large range of vertebrate prey, from fish, turtles, and penguins, to seals and other whales.
Blue whale (Balaenoptera musculus), southern and western Australian coasts
Blue whales are the largest animals on Earth, growing up to 33 metres in length and weighing up to a massive 200 tonnes! To keep that big body going they have to consume about 4 tonnes of krill daily.
Southern right whale (Eubalaena australis), southern Australian coast
Southern right whale males have the largest testicles of the animal kingdom – around 500kg each (that’s one tonne per male).
Dwarf minke whale (Balaenoptera acutorostrata), coastal and offshore waters along WA, SA, VIC, NSW and QLD.
Female dwarf minke whales have a gestation period of 10 months and give birth to 2 metre-long young that are weened after only 6 months together.
Australian sea lion (Neophoca cinerea), southern coast including WA and SA
Australian sea lions are the only seal that does not breed annually, instead getting together every 17.5 months.
Dugong (Dugong dugon), coastal northern Australia (all year)
Dugongs are considered the origin of myths about mermaids and sirens, a link usually attributed to pectoral mammary glands (which have been likened to human breasts) and long period of close calf dependency.
Humpback whale (Megaptera novaeangliae), southern, eastern, and western coasts
One of the most recognisable species of whales, humpbacks have distinctive knobbly protuberances on their heads and long flippers and individuals can be identified by their characteristic black and white patterns.
Australian humpback dolphin (Sousa sahulensis), tropical coastal waters of northern Australia
Humpback dolphins can best be observed in river systems, a preferred habitat to catch a fish snack on the change of tide. They are also notoriously boat shy and don’t bow ride, making it difficult to observe in the wild.
Polling to determine the finalists of Australian Mammal of the Year is now closed. The Top Ten finalists will be announced on Monday 15 August and final voting for the Mammal of the Year will begin!
Originally published by Cosmos as Splish Splash! Why our amazing marine mammals deserve your vote
Gabrielle Genty is a molecular evolutionary biologist interested in the genomics, evolution, and adaptation of cetaceans. As a PhD candidate at Flinders University, her project focuses on the genomics of baleen whales with a focus on the splendid blue whale.
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