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Highlights under Water

Under the water along the Australian coast you will find an unbelievable diversity. On 4 oceans or alternativelty 3 great ocean systems the habitats range from tropically warm to mildly cool. Here hundreds of plant and animal species that occur only here (endemic), could develop. Four main habitats are recognized: the open ocean, the reefs, the coasts and the bays. These habitats are home to the Australian underwater flora and fauna. The make-up and spread of the animal world is dependent on the ocean currents that are caused by winds, the rotation of the earth and the gravitational pull of the moon. The tides only have a partial influence on the currents.
Australia's Ocean Inhabitants
Australia's underwater world has mild as well as tropical habitats with an enormous variety of marine species. Beginning with phytoplankton, which is important to photosynthesis, during which oxygen is produced as a by-product. Via the zoo plankton the waters of Australia provide in excess everything that is essential to marine life: seaweeds, algae, sponges, cnidaria, black corals, tube anemones, soft corals, sea fans, sea pens, hard corals, sea anemones, worms, sea mats, crabs, lobsters, prawns, shrimps, snails, nudibranches, mussels, squids, cuttlefish, paper nautilusses, octopusses, echinoderms such as star fish, serpent stars, sea urchins, sea cucumbers and many more. Fish form the biggest vertebrate group. Australian waters are home to nearly 3 600 species of fish. Since the rise of scuba diving about 30 years ago, hundreds of new species have been discovered. Some of these only occur in southern waters.
The hawksbill turtle lives in most of the tropical waters of the world. From October to March the female lays about 50 eggs on island beaches and coral sand banks, then after ± 8 weeks the young hatch.
The snake most commonly found in the tropical waters of Australia is the olive brown sea snake, the colour of which varies from brown to yellow. It is active during the day and at night as it searches for food in corals and rock crevasses. In intervals of 10 to 20 min. the snake has to surface to breathe. When sleeping it can remain under water for many hours. One should treat sea snakes with great caution, as their poison is deadly.
Even though dolphins are seen as inhabitants of the open ocean, one can come across them in bays, harbours and inlets all over Australia. They are sociable animals, that usually appear in groups. They have to come up for air often, and therefore usually swim close to the surface of the water.
The occurance of the Australian fur seal is limited to a few solitary rocks off the Australian south and southeast coast. There are breading colonies that consist of more than 10 000 seals, while elswhere only around 20 animals can be found.
Colonies of Australian sea lions can be found along the beaches and islands of the south and southwest coast.
The geographic range of the protected seacow or dugong stretches from Shark Bay (WA) as far as the northern Moreton Bay (QLD), even though some of these animals have been seen further south at Port Stephens (NSW). Seacows are usually very shy animals, that live in family groups and feed on sea weed.
The southern hemishere is home to the southern right whale which comes to the shallow waters along the south coast of Australia to calve. This is of great importance, as the southern right whales only have 1 calf every 3 years, and this calf then remains with its mother for 14 months. The southern right whales are fully protected in Australian waters and one can incur a heavy fine if one approaches them too closely while boating or swimming. On the other hand one can snorkel with minke whales in the northern Great Barrier Reef between June and July, which is probaly one of the most special experiences that Australia can offer.
Rare and Unusual Species
Most animal species that occur in tropical coral reefs, are found all over the world. In isolated cases the families, genres and species can differ in various ways, but usually they are very similar to each other. The tropical species are said to have originated in the waters around Indonesia and to have spread from there across the oceans. In the case of many tropical marine animals the larvae are transported from one reef to the next by ocean currents. Most of the tropical species are therefore spread over a wide area and there are only a few rarely occuring species, whose habitat is limited to a specific reef. Of course there are also exceptions. In the mild waters of the south many of the unique marine animals of Australia could develop in complete isolation. For instance during the last few years a few new species have been discovered at Lord Howe Island: the Lord Howe coral fish and the Lord Howe hydro coral. Numerous marine animal species occur exclusively in Australia, eg. sea dragons, some kauris, certain fish speces etc.
Sharks & Rays - where one can come across them
In Australian oceans one comes across numerous shark and ray species. In Western Australia a bay (Shark Bay) was even named after the sharks that occur in huge numbers in the area. Up to now more than 180 shark and 100 ray species have been identified, of which some have, however, not been described yet. The population size and spread area varies throughout the country, but there are certain places, where some species are very common.
For grey nurse sharks the best place is the area off Forster/ Tuncurry and Seal Rocks (NSW), north of Brisbane (in winter - QLD) and south of Montague Island (in summer - NSW).
There are 6 different species of wobbegongs. The biggest populatioms can be found between Sydney (NSW) and Brisbane (QLD).
Port Jackson sharks are most common off the coast of central and southern New South Wales, where one can occasionally come across dozens of them in caves.
Hammerhead sharks live in tropical oceans and in the Pacific Ocean among other places. In Australia they are often sighted in the northern Coral Sea (QLD) as well as around Christmas Island.
Guitar fish are among the most conspicuously patterned rays. They live especially in the waters of South Australia. One of the biggest populations lives inJervis Bay (NSW).
There are 8 species of electric rays in Australia, of which only 2 are regularly sighted by divers, eg. off Hobart. In Jervis Bay (NSW) there are short-tailed electric rays.
One comes across the big manta rays most often in winter off Lady Elliot Island and Brisbane (QLD), the Ningaloo Reef (WA) and the Whitsunday Islands (QLD).
Whale sharks - the giants of the Ningaloo Reef - occur mainly off the Ningaloo Reef (May/June - WA), off Christmas Island (November/March - south of Indonesia) and along the Gove Peninsula (in summer - NT). The increase of the corals and the breeding of the tropical krill on the Ningaloo Reef attracts the whale sharks. These days several thousand divers come every year to look for these animals, and meeting a whale shark close up is probably one of the most breathtaking experiences in the life of a diver, especially when one is surrounded by several of them at the same time. Divers are prohibited from touching the animals and there may not be more than 8 snorkelers around a whale shark at the same time.
Coral Spawning - the annual reprodution of the corals
Coral Spawning is among the most spectacular events that one can experience under water. A night dive through the drifts of pink reproductive cells that rise to the warm surface of the water, is an unforgettable experience. It takes place every year along the Great Barrier Reef in the late spring November/ December and along the Ningaloo Reef (WA) in March/April. Coral polyps normally reproduce asexually. However, during the annual sexual reproductive cycle far more offspring, spreading over a greater area, are produced. 4-5 days after the full moon more than 160 of rock corals reproduce simultaneously. Many of them are bi-sexual, i.e. they colourfully release both ova and spermatozoa into the water, and these then rise to the surface where they separate. The ova repel spermatozoa from the same coral stock, while they attract other spermatozoa of the same species. After fertilization has occured, free swimming larvae develop out of the ova and form pink carpets on the water surface which drift with the currents. After 5-20 days the larvae swim to the reef and attach themselves to an available space, where they then establish a new coral colony. The polyps repeat this process, so that many thousands of polyps eventually start forming a new structure. When the water is teeming with larvae, predatory fish are quickly satiated, leaving many larvae alive to populate the reefs. Together with the corals other marine animals such as giant mussels, feather stars and sea cucumbers also reproduce and thereby guarantee exciting night dives. As factors such as water temperature and the tides influence this reproductive process, the exact point in time of this reproduction occuring, is difficult to predict.
The Great Barrier Reef - the world's biggest under water protected area
The Great Barrier Reef (GBR) is the biggest and probably the most impressive coral reef on earth and is regarded as one of the 7 natural wonders of the world. In 1981 it was declared a World Heritage Site. In 1975 the Great Barrier Reef Marine Park Act, putting the whole area under protection, was promulgated. The area is divided into zones, each of which is closed to certain activities. The GBR is situated northeast of the Australian mainland along the east coast of the federal state of Queensland in the southern Pacific and extends from the Torres Strait off Papua-New Guinea to Lady Elliot Island about 75 km northeast of Bundaberg. It is meanwhile 2 300 km long and extends from the 10th to the 24th southern degree of latitude. The reef runs along the eastern edge of the Australian continental shelf. It is between 30 km (near Cairns) and roughly 250 km (near Gladstone) off the Australian east coast, completely within the toropics and in the tropical cyclone area. The tropical cyclone season lasts from October till March, but the highest rainfall occurs in the autumn (February/March). The GBR consists of a chain of more than
2 500 individual reefs as well as nearly 1 000 continental or coral islands, making it the biggest reef system in the world. The total area of the GBR is about 347 800 km² and it can be seen from outer space with the bare eye. The reefs offer a habitat for more than 400 coral species, more than 1 500 fish species, several thousand molluscs and crustaceans, 800 species of echinoderms, such as starfish, 500 different species of sea weed, 23 different marine mammals, 16 sea snakes and 6 of the 7 turtle species occuring in the world. Among these are the loggerhead turtles which are threatened with extinction and the green Pacific turtles that use the reef to lay their eggs. Also threatened with extinction are the dugongs (seacows) living there. Humpback whales use the warm waters to bring their young into the world.
The Great White Shark - a threatened species?
The great white shark inhabits the moderate as well as the tropical oceans, but especially the colder waters, where it feeds on dolphins, other sharks, seals, rays and deep sea fish. In general the female gives birth to fewer than 10 baby sharks, which are 1m long at birth. Great white sharks are most common along the south coast of Australia. It is the dream of many divers to see this magnificent marine animal in the water, even though this particular shark is held responsible for most of the fatal attacks on humans. The surest method to get to see these animals, is to pour a bucket full of some form of bait into the sea. Diving excursions with shark cages depart from Port Lincoln and proceed to the Neptune Islands. Divers from all over the world come to Port Lincoln, in the hope of seeing a white shark, but it seems as though these sharks are becoming scarcer. Only recently the great white shark was proclaimed a protected animal in Queensland, New South Wales and Tasmania. Their numbers are mostly endangered by the use of long line nets by commercial fishermen. It would be difficult to protect the great white shark all over Australia, as scenes from the film "Jaws" persist in the memories of most people.
Wrecks
Diverse wrecks, which can be explored by divers, lie all around the Australian coast. Probably the most famous is that of the SS Yongala off Townsville on the east coast - a highlight of your Australian holiday that can be experienced on a day tour. Also suitable for a day tour are the wrecks of HMAS Swan off Dunsborough and HMAS Perth off Albany in Western Australia.
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