What Is An Endemic Species?

A global biodiversity hotspot, the Great Southern Reef is home to many species found nowhere else on the planet

Weedy Sea Dragon (Phyllopteryx taeniolatus) by Mike JonesOriginal Source: www.mikejonesdive.com

Endemic Species (def.)

Species of plants and animals which are found exclusively in a single defined geographic location.

Harlequin fish by Scott BennettGreat Southern Reef Foundation

Unique species of the GSR

Australia's Great Southern Reef (known as the 'GSR') is home to thousands of unique marine species that are found nowhere else on earth - and scientists believe that there are still tens of thousands yet to be found and studied.

Let's take a peek at just a few...

Australian Sea Lion at Kangaroo Island by Stefan AndrewsOriginal Source: @ocean_imaging

Australian Sea Lion

Meet one of the rarest animals in the world.

Australian Sea Lion by Stefan AndrewsOriginal Source: @ocean_imaging

A rare beauty

The entire Australian sea lion population lives along the southern and western coastlines of the Great Southern Reef with about 85% living in South Australia and the other 15% in Western Australia, and they are the only endemic pinniped in all of Australia.

Australian Seal Lion at Baird Bay by Gergo RugliOriginal Source: www.rugliphoto.com

Fin footed

Seals and sea lions are marine mammals called pinnipeds (meaning fin footed). Sea lions can be distinguished from seals by the small flaps for outer ears. 

They are recognisable by their short blonde or ash grey fur, creamy coloured underbellies, short flippers and bulky body.

Australian Seal Lion at Baird Bay by Gergo RugliOriginal Source: www.rugliphoto.com

Specialised ocean hunters

Agile in both the water and land, sea lions can hold their breath for up to 12 minutes. Known as benthic foragers, they feed from the sea floor on species like cuttlefish, lobsters and rays.

Their complicated breeding cycle makes them a vulnerable species.

Australian Sea Lions at Pearson Island, South AustraliaGreat Southern Reef Foundation

Weedy Seadragon in Golden Kelp by Stefan AndrewsOriginal Source: @ocean_imaging

Weedy Seadragon

A charismatic creature, the weedy seadragon's appendages resemble the kelp fronds found in their habitat.

Weedy Sea Dragon (Phyllopteryx taeniolatus) Male by Mike JonesOriginal Source: www.mikejonesdive.com

Distinctive dragons

The weedy seadragon’s leaf-like appendages resemble the swaying kelp fronds found in their habitat. They drift gracefully around seaweed beds and seagrass meadows relying on camouflage and stealth to approach their unsuspecting prey.

Weedy Sea Dragons (Phyllopteryx taeniolatus) by Mike JonesOriginal Source: www.mikejonesdive.com

Despite its charismatic nature, few studies on the Great Southern Reef’s weedy seadragon have been published.

In 2021, in a first of its kind study by Klanten and colleagues, it was proposed that there were four genetically distinct populations of weedy seadragons along the GSR.

Lifecycle of the weedy seadragon. Juvenile to AdultGreat Southern Reef Foundation

Port Jackson Shark (Heterodontus portusjacksoni) by Gergo RugliOriginal Source: www.rugliphoto.com

Port Jackson Shark

The Port Jackson shark is a nocturnal, bottom dwelling ‘bullhead’ shark endemic to the Great Southern Reef 

Port Jackson Shark by Gergo RugliOriginal Source: www.rugliphoto.com

The shark's territory is habitually on or near the sea bottom, which is also its feeding area. They use the seagrass areas to camouflage with their pattern markings.

Port Jackson sharks are a nocturnal species and are most active right in the middle of the night. 

Port Jackson Shark by Gergo RugliOriginal Source: www.rugliphoto.com

These sharks have a small mouth containing small molar-like teeth in the rear of the mouth to crush prey which may be urchins, crustaceans, molluscs or small fish.

Port Jackson Shark by Stefan AndrewsOriginal Source: @ocean_imaging

Annual migration

These sharks will congregate in large numbers in shallow waters in late springtime to mate. Males arrive first in harbours and bays and females usually arrive weeks later. 

Mating involves biting, with the male grasping the pectoral fin, dorsal fin or flank of the female 

Blue Groper by Gergo RugliOriginal Source: www.rugliphoto.com

Scott Bennett reflects on diving with Blue Groper

Blue Groper

The GSR supports both eastern and western blue groper. The separation of the two species can be traced back to the Ice Age, when waters became cooler and the blue groper population likely split and moved up the west and east coasts. 

Eastern Blue Groper by Ian DonatoGreat Southern Reef Foundation

A large bony fish, they can grow to be up to 1.7 metres in length, and are not fully grown until they are about 30 years old. Even though they are called a ‘groper’ they are actually a large wrasse.

Blue Groper by Stefan AndrewsOriginal Source: @ocean_imaging

Female first

These gropers are what is known as a protogynous hermaphrodite, meaning the entire species begins life as a female and some, but not all, change sex to males later in life. 

Western Blue Groper in Golden Kelp by Imogen ManinsOriginal Source: @imogenisunderwater

Females reach sexual maturity at about 15 years, but the change from female to male can take up to 35 years. This change usually occurs when they reach around 82cm in length and their colour changes from green to blue.

Blue Groper by Gergo RugliOriginal Source: www.rugliphoto.com

Sheriffs of the Reef

Considered a keystone species, blue gropers are an important part of the marine ecosystem. 

Sydney harbour's incredible marine life revealed by Reef Life Survey diversGreat Southern Reef Foundation

Credits: Story

To keep up to date with the latest GSR information and initiatives, visit our website and sign up for our newsletter. Our Educator Hub also offers teachers and students downloadable lesson plans to use in the classroom. 

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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