Thanks to its exotic climate and its relative isolation from the outside world, Australia has developed a completely unique plant and animal life that most tourists experience as something spectacular. The continent’s isolation from the outside world made it difficult for other species to get to Australia, creating an opportunity for a plethora of unique indigenous species to develop and establish themselves.
While large parts of earth’s continents suffered a major cooling down (with a culmination in about 10,000 years ago), Australia’s animal species were given additional time to evolve when chance had the continent moving northwards towards increasingly warmer lands instead. On top of this, Australia’s mainland has always had an extremely diverse climate, all with unique conditions (such as the rainforests of the tropics) giving many different animals a chance to evolve its own uniqueness suitable for each region and its specific environment.
The development of Australia’s unique wildlife and nature
In some national parks in Australia you will encounter the name Gondwana, which is the name of the supercontinent that Australia was part of about 100 million years ago. At that time Australia was covered by rainforest and many of the plants that you encounter in the country today originate from the time of Gondwana. Some of the great ferns and fern trees you can see in specific areas is just like stepping back in time to the time of the dinosaurs. Australia and New Guinea (present-day southern Indonesia) broke away from Antarctica 50 million years ago and moved northwards. During this time Australia became increasingly warmer and gradually drier. The rivers and large lakes that once existed in the inland of Australia dried out resulting in thick foliage plants and species that thrive in arid areas started replacing the rainforest plants, spreading further and further out. These forests and grasslands continued spreading across the country, eventually being replaced themselves by semi-desert plants like very low shrubs that required less water and could withstand heat better. This dry and nutrient-poor soil pushed the local flora to develop heat-resistant and water-efficient properties that minimize water loss. For example, the leaves of Eucalyptus trees are much harder than the leaves we see on trees in Europe because they have a hard, thin shell to minimize water evaporation.
The increasingly drier landscape made the number of forest fires to rise. The plants adapted to this in multiply ways, like having the root systems to quickly push out new shoots or the trunk to shed bark. Even if the crown of the shrub or tree is burned it may still survive. Examples of plants with this ability can be found in the banksia genus and several kinds of eucalyptus. Other interesting adaptations to mention is the Australian grasstrees (genus xanthorrhoea) and some orchids that only bloom and emit seeds after they have been exposed to excessive heat during a forest fire.
In order to survive the increased drought many species had to find refuge in the cooler and relatively wetter areas around the Great Dividing Range along the east coast. This is where we in at the present will find areas with the highest number of species in Australia. There are forest areas off the coast in the highlands where you can find plants and animals that have not significantly changed since the age of the dinosaurs, in 70 million years.
Mammals and marsupial
Australia’s unique wildlife is for many tourists one of the most important reasons to visit Australia.
More than 80% of all mammals, reptiles, frogs and plants in Australia can’t be found elsewhere in the world. For those who are interested in nature – you are up for some unforgettable experiences. Most of the country’s animals are hard to find in the wild, but across the country there are world-class zoological gardens and aquariums where you can become acquainted with them on a one-hand experience.
Unlike the rest of the world, there are relatively few higher order mammals (also called placental mammals) in Australia. Instead, marsupials (also a type of mammal) have evolved to take a dominant role in many ecological niches thanks to the absence of competition and dangerous predators. The difference between the two types of mammals (slightly simplified) is that marsupial babies are always born “premature” and are in need to evolve further in a pouch located outside the womb before they are fully developed. In the higher order mammals, like the human, the baby is fully developed while in the mother’s womb (attached to the placenta) during pregnancy. The offspring of the marsupial will continue its growth into a fully developed baby after birth while in a pouch (also called a marsupium) on the mother’s stomach, allowing all organs to develop and get viable. The term placental mammals, however, is somewhat misleading. Even a few marsupials, like the koala, have a simple placenta, but with the difference that it doesn’t support the baby’s full development as it does in the body of a placental mammal.
Thanks to Australia’s isolation and lack of large predators (the largest predator is the wild dog dingo), marsupials has developed many different roles depending on the local climate and the varying conditions within each area. This resulting in marsupials to live both as predators, herbivores and insect eaters. There are species that jump, fly, and climb. The similarity of some marsupial and other mammals from the rest of the world (such as the resemblance between koalas and bears, wombats and badger and possums versus mice and rats) is not evidence of kinship but the consequence of the development of species in similar ecological niches in different parts of the world (a phenomenon known as convergent evolution).
There are over 140 species of different marsupials living in Australia. Some of the most famous species are the kangaroo, koala, wombat and wallaby (a minor relative of the kangaroo). There are 55 varieties of kangaroo and wallaby and they are available in all sizes; Small rascals from 500 g to large “don’t mess with me” ones up to 80-90 kg.
Both koalas and kangaroos are found in large numbers around the country. If you’re driving in the countryside, especially close to the sunset, you are highly likely to see wild kangaroos jumping across or next to the road (so be aware).
Within the order of higher animals (with placenta and without pouch on the mother’s belly), there are only some varieties of bats, mice and rats that occur “naturally” in Australia (without being introduced by humans). The many other mammals in Australia, which we recognize from the rest of the world, have in one way or another all gotten to the country with man’s help.
The first animal to arrive in Australia with man’s help was the wild dog dingo. It’s believed to have come ashore with people migrating from the north about 5,000 years ago. When the Europeans began to colonize Australia, they brought a variety of different species with them, some deliberately, others by mistake. Some of the most unwise things that was done was to release foxes, hares and rabbits to roam freely in the Australian landscape. Since then these introduced species have done tremendous damage to Australia’s nature and native animals. Other species that have been transported here and now live feral in different parts of Australia are, for example, the house cat (yet another dangerous predator that is hunting relentlessly on the indigenous animals), different kinds of deer, wild horses, domestic pigs (wild boar) and dromedaries (camels with a hump). Many tourists in Australia are surprised when they are told that there are more than one million dromedaries in the wild, a legacy from the 1800s when the animal was used as a mean of transport through the desert.
The koala is one of Australia’s most famous marsupial. The iconic animal lives in the wild along the entire east coast where their sole source of food can be found, the eucalyptus forest. It eats almost solely leaves from eucalyptus trees and spends most of its life up in the canopy, either by sleeping and resting for up to 20 hours a day, or by eating the leaves. They weigh 5-12 kg and are between a half up to a meter long, have woolly fur that’s white, light grey and brown. The koala can live above 15 years of age if free from disease. Until the beginning of the 1900s, the koala was hunted for its fur, but is now protected and has recovered reasonably well (but still needs protection to properly re-establish itself).
The kangaroo and its smaller cousin wallaby are the ones after the koala that most people know about regarding Australian wildlife. There are four species of kangaroo, but generally one only talks about grey or red kangaroos. The red kangaroo is the largest in the family, some males can be as tall as 2 meters and weigh up to 90 kg. The grey kangaroo is the most common type of kangaroo and is spread throughout the eastern part of Australia. If you drive in the countryside it is difficult not to see any grey kangaroo on the journey. Kangaroos move by jumping and this has turned out to be a very energy efficient way to get from A to B. Kangaroos and wallabies have developed large elastic tendons in their hind legs. These act like springs when they jump, making the animal bounce forward which requires less muscle work than walking forward.
When bouncing on the hind legs it automatically helps the kangaroo to push out and pull air into the lungs, another energy efficient benefit for the animal. The ability to travel long distances over an arid landscape in search of pasture has been the key for the kangaroo and its relatives to spread across the country. Wallaby is the name for the smaller species of kangaroo animals, and the boundary between the two is a bit diffuse despite it being based on the animal’s size – sometimes you can hear the term wallaroo for the species being on the border in terms of size.
We’ll move on with the fun marsupials. A possum is one in around 70 different species of marsupials with long thick tails that look a little mix between a raccoon and squirrel. They are nocturnal and herbivores or omnivores. Common brushtail possum is the species that is most associated with the word possum, and they are found in large numbers around southern and eastern Australia. They mainly live in trees, but also on the ground. At night and late evenings, it is common to hear their calls in the suburbs or any area with lots of trees and foliage between houses. They don’t seem particularly afraid of people, and often they take the chance to get fed or on someone’s fence, or by climbing out on a branch close to you or even from people just happening to walk by. The common brushtail possum like to visit people’s gardens, feasting in a fruit tree or a vegetable patch. If you look closely, sometimes you can see some possum mothers having their offspring riding on their back.
A wombat is a short and muscular animal reminding of a hefty guinea pig. It has brown fur, a short tail and can grow up to one meter in size. They dig out vast burrows underground where they spend hot days only to come out at night or in overcast weather to eat grass, bark and roots. The animal weighs between 20-40 kg and are despite their size powerful little animals with only the dingo as a natural enemy. Wombats defend themselves by hiding in their tunnels by turning their buttocks that consist of thick fur, cartilage and bones outwards against the enemy, thus blocking the way. This defensive behaviour is not at all successful when they are about to be hit by a car; Instead of running off the road they snuggle up and wait for their hard butt to protect them, which of logical reasons doesn’t work against a car. An interesting adaptation of the wombat is how the opening of the pouch (where the newborn rests and grows) is facing backwards, minimizing the risk of dirt and sand to find its way into the pouch when the mother digs in the ground.
Monotremes are a group of mammals that lay eggs and are only to be found in Australia. Perhaps the most well-known monotreme is the platypus which looks like an otter with a broad and flat bill. Echidna is the other type of monotreme found in Australia. It looks a bit like a mixture of a hedgehog and a small anteater.
The platypus is found along the entire east coast, from Tasmania up to the tropics of North Queensland. The animal is between 40-50 cm long on average, has dark brown fur, weighs 1-2 kg and has flat beak and webbed small paws to help it move in water. By digging steep into the soil along rivers the platypus creates burrows where the female incubates her eggs until they hatch. After hatching, the baby platypus breastfeeds the mother not through nipples but by releasing milk through her skin halfway up on her belly, like how sweat glands would work. The animal is a good swimmer and can stay underwater for up to 15 minutes to look for food. They eat freshwater shrimp, crayfish, insect larvae and worms amongst other things by either catching it in the water or by digging it out of the riverbed. Platypus are known for their flat tails (which look a little like a beaver’s) and because the males have a small venomous spur on each hindleg. They can use it to defend themselves. Unfortunately, it has proved difficult to use when defending themselves against introduced fox. The platypus is at the present considered a threatened species and therefor protected.
The echidna is found all over Australia. It is a small, round animal with large clawed feet, a blunt, long snout and a fur that is covered in sharp, flexible spines. Echidnas lives almost exclusively from termites, which is why they sometimes are called spiny anteaters. The echidna lays eggs. After being hatched the baby echidna lies in the mother’s pouch until its thorns has evolved and it is ready to fend for itself. The thorns are used primarily for defence and just like a hedgehog it rolls itself up to a ball when threatened. Some individuals also bury themselves halfway into the ground until only the sharp thorns remain above the surface.
There are over 800 bird species in Australia, of which about half of them cannot be found elsewhere in the world. These range from small honeyeaters to giants like the ostrich-like emu which can grow up to two meters in height. Other exciting birds are 55 species of colourful parrots, and many tourists are struck by how these beautiful birds live free not just in exotic places but also inside residential areas.
Wild cockatoos are playful and ever so loud when gathering in large groups – one of the most common species is the larger cockatoo (Sulphur-crested cockatoo) which is about half a meter long and is beautifully white with a distinctive yellow crest on its head. They can become very old, and in the zoo, individuals have become as old as 82 years. Because of its loud call, acquiring it as a pet might upset the neighbours.
Other well-known cockatoos that you can see wild in Australia are galah (read breast with grey wings and pale pink crest), cockatiel (a smaller bird with grey breast, white wings and yellow-orange head), corella (smaller grey-white birds with pale beak, yellow under the wings and red a face) and palm cockatoo (with black feathers, red cheeks and big black beak).
Cockatoos and parrots often socialize in large groups and often stay close to their partners – the male and female form strong monogamous couples who often endure their entire life. Rainbow lorikeet, a common parrot on the eastern seaboard, from northern Queensland to South Australia, often shows up in pairs and is found in large numbers where people live.
If you are lucky you can manage to get a pair of lorikeets to settle down on your balcony railing where they let you feed them with finely cut fruit pieces. You recognize them on their rainbow plumage, lack of crest and noisy call.
Other well-known and common Australian parrots are the rosellas. The crimson rosella with its beautiful red body, blue wings and blue tail is a splendid sight that is commonly found around cities in eastern Australia.
Flightless ostrich birds can be found in Australia. The largest bird on the continent is the emu and the smaller is called cassowary. The emu is Australia’s national bird which is found in large parts of the country; On some plains and forests as well as in parts of the inland bushland and desert. It resembles the ostrich by look, can be up to two meters and weighs between 30-45 kg. The plumage goes in a beige tone while the colour of the neck, head and legs is dark brown and black. Although it cannot fly, the emu is a migratory bird which migrates to areas rich in edible plants after rain periods.
The cassowaries are terrestrial birds just like the emu, but unlike the widespread emu the cassowaries only occur in some forest areas of northern Queensland. The body plumage is black, its neck is clear blue and at the top of the head is a hard, brownish comb that looks like a small elongated helmet. Most birds measure just over 1.5 m and weighs about 40-50 kg. It is believed that a cassowary can become 40-50 years old. Even though they avoid humans and mostly stay in the woods, they are known to run at speeds up to 50 km/h and those strong legs can produce a lethal kick forwards and downwards that can pose a threat to people.
Kookaburras is something of a national symbol for Australia. These birds are big kingfishers well known for their loud calls sounding a bit like human laughter. A kookaburra is a carnivore that mainly eats fish and small animals like lizards and snakes. Quite often they come up close to get fed minced meat or thin slices of meat from the grill.
The black swan has a jet-black plumage and red beak and is relatively common around large lakes and wetlands along Australia’s southeast coast areas.
The lyrebird is an Australian bird well known for its tremendous ability to mimic. It can mimic songs of other birds but also sounds created by people such as mobile phone ringtones, alarm clocks and various musical instruments, including complete melodies that’s been played by people in the vicinity of the birds. Lyrebirds sing all year round and mixes their own sounds with components from other birds’ songs and the surroundings to create a uniquely beautiful composition. The birds have long tailfeathers that looks a bit like a plume made from single peacock feathers. The lyrebird lives mostly on the ground and can be found in temperate rainforests of Victoria, New South Wales and southeast Queensland. They are shy and hard to spot, but the easier to hear.
The common black and white feathered Australian magpie, not known for its beauty but for its beautiful singing. The song that resembles the sound of a flute can often be heard in the evenings. The magpie is also known for its territorial aggressive behaviour during spring when they nest. Some males defend their nests against everything and everyone – including people who unsuspiciously happens to walk or cycle past the magpies’ nests.
It is easy to confuse a magpie with a currawong. Currawongs is larger than magpies and is recognized on its yellow eyes (a magpie has red eyes). When inside tree foliage the currawong also seems to fly around in a flapping, almost clumsy style.
Reptiles and frogs
Twenty-one of the world’s 25 most venomous snakes lives in Australia, but besides venomous snakes there are also several pythons and harmless grass snakes. In the northern parts of the country (for example in the Kimberley and Kakadu National Park) there are both salt- and freshwater crocodiles. Turtles and sea turtles are also found in the country (but many of the latter are threatened with extinction).
There are lots of different types of lizards in a range of sizes in Australia. The biggest one is the goanna lizard, a monitor lizard that can grow up to one meter in length. It is related to some of the largest lizards in the genus Varanus. In general, most lizards in the country are small and non-venomous, a nice reminder when one sees small lizards, so called skinks, scurrying about on the house wall or amongst rocks where they hunt for flies and other insects.
Lizards are often welcome in gardens in Australia as they eat cockroaches and other insects that most people don’t want in their homes. Next to the skinks, the dragon lizards are common to spot in national parks and recreation areas. To get some nice photos keep an eye out for the goanna (which can be seen climbing in trees), blue tongued lizard (a thick lizard with a blue tongue) and eastern water dragon.
There are two kinds of crocodiles in Australia, the large saltwater crocodile (also called “saltie”) and the slightly smaller freshwater crocodile (also called “freshie” or “Johnstone river crocodile”). The larger of the two can grow up to 6 meter in length. Both types live in rivers, estuaries and coastal areas of northernmost Australia, even though the freshwater crocodile mostly stays in the inland of the north.
The large saltwater crocodile is the world’s largest crocodile and it can fight big prey by surprising and dragging it out into the water. Most of the crocodile attacks on humans have been made by the large saltwater crocodile. The freshwater crocodile is only found in Australia and does not see people as a possible prey, it tries to avoid humans. But the saltwater crocodile might get the idea of sneaking up on bathers to get itself a meal, so make sure you look for warning signs in national parks before you take a swim.
The freshwater crocodile lives further upstream and do not protect their eggs as strongly as the saltwater crocodile whose females guard their newly laid eggs until they hatch. One big problem for the inland crocodiles is that they eat the introduced species cane toad which is poisonous for crocodiles eating it.
Cane toads are the only toads found in Australia, but it doesn’t belong in the country. Its presence is a result of one of the most spectacularly stupid decisions taken in Australia. The toad was introduced by humans in the country in 1935 to control pests on sugar plantations in Queensland but instead it spread rapidly across the north-eastern parts of the country. It is a threat to indigenous fauna by outcompeting and eating local animals. It has no natural enemies (except a few snakes) that can eat it without being poisoned by its poisonous mucus. The toads are widely hated in North Queensland and for a long time, ways to kill and eradicate the giant toad (they can be more than 15 cm long) have failed.
Snakes are common all over Australia, but most wild ones seen are the ones having the misfortune to be run over by cars while crossing roads. If you’re out walking in high grass, it is a good idea to make some noise. That way any nearby snakes bringing up their body temperatures by sunbathing can get a chance to get away. If you discover a snake in front of you, stand still or quietly go back so the snake doesn’t feel threatened. Stomping with your feet within reach of the snake can make it feel threatened with the risk of it trying to attack your feet or boots. None of Australia’s snakes are aggressively looking to attack people, so if you just give them a chance to escape, they will stay away from you.
The taipan is the longest of Australia’s venomous snakes. It can be up to 3 m long, although most are just over 2 m. It is light to dark brown and sometimes almost black and often found in cultivated areas or plantations. The taipan is found along the coast from Brisbane to Darwin where it mostly eats mice and rats. Inland taipan (or fierce snake) is not as big as the taipan on the coasts. It’s dark brown or a brownish light green, feeds on rodents and small birds and is found in the Outback in southwestern Queensland, northeast South Australia and in Northwest New South Wales. Unlike many other venomous snakes that bite once to let the venom do its work, inland taipan is particularly aggressive and can bite and inject poison into his victim up to seven times in a single attack.
The snake with the charming name death adder is a venomous land snake, another one of the most venomous snakes in Australia and the world. It is light brown with brownish-black stripes, can be up to half a meter long and occurs mainly along Australia’s eastern and southern coastal areas. It thrives in woodland and on grasslands where it is often camouflaged among sand, leaves and twigs waiting on its prey. Death adders are the only snakes that doesn’t back a millimetre if threatened by humans, even if you are about to accidentally step on it. A good reason to wear proper boots when you’re out and about in the bush.
The eastern brown snake or common brown snake is like the death adder a venomous land snake. The brown snake is a reptile to stay on a good distance from due to its strong venom and extremely aggressive behaviour if threatened. Despite its name, the colour can vary from brown, black, orange, combined with a tone in silver or beige. Most brown snakes are about 1.5 m long, although occasional individuals may be longer than two meters. They are located along the entire East Coast, are day active and very fast if provoked – when in defensive position it can rise into an S-shaped position with the head high above the ground ready to bite. It eats small vertebrates and often hunts near farms and plantations where rats occur. The brown snake is the world’s second most toxic land snake (inland taipan is number one) and there are reports that people have died from its poison just a few hours after being bitten. In 2007 a nine-year-old girl outside Armidale in New South Wales died just two hours after she was bitten in the foot by an eastern brown snake when collecting corn from the family’s vegetable garden (she collapsed unconscious after just a few minutes).
Spiders and insects
Australia has some of the world’s most venomous spiders, but their bad reputation is exaggerated – no one has supposedly died of a spider bite since 1981. In this article we look at some “creepy crawlies” worth knowing.
It is not uncommon to find the Sydney funnel-web spider in and around Sydney, one of the world’s more dangerous spiders. If threatened when approached they can act aggressively by lifting their forelimbs up in the air. The spider is easy to spot and therefor avoid considering it can become 5-6 cm long. Occasionally they fall into people’s swimming pools (they can survive under water for a short time by breathing oxygen from the air bubble surrounding their body) and being unable to get out they feel threatened and the risk of attacking close by people is increased.
En vanligare spindel är den välkända redback-spindeln (på svenska kallar vi dem rödryggad spindel, och den är släkt med den sydamerikanska svarta änkan). Som väl är verkar det som att redbacks endast biter människor om man lyfter upp dem eller petar på dem.
A more common spider is the redback spider, another venomous spider. It appears that redbacks only bite people if one lift them up or poke at them. Normally they are quick to hide when someone gets nearby, but these too occasionally end up in people’s swimming pools or hide under outdoor furniture, in kids’ toys or somewhere shady. So have a look under edges and in crevices.
Another spider that might frighten people is the huntsman which is a fast runner that can grow to the size of a human hand. If you see one crawling by, it’s probably about to climb a wall or a trunk in search of insects to eat – remind yourself that your visitor the huntsman is a good helper when it comes to keep insects as cockroaches and flies away.
It is estimated that there are about 10,000 species of spiders all over Australia. Other common species that may be of interest are the orb weavers, white-tails and black house spider. Orb weavers make gigantic webs and can often be seen in parks and gardens (and no, they’re not toxic). The white-tails are recognized by their little white spots on their back body, almost like a white tail, and how they seamlessly can climb on glass panels and upside-down in the ceiling.
Although the risk of dying from a spider bite is low, beware of them and seek medical advice if bitten. The bites from a huntsman, funnel web and redbacks are very painful.
Except from a lots of orb weavers outdoors I have only seen a few spiders (a pair of huntsmen and redbacks) in Australia’s cities since I moved here in 1999. Personally, I have never been bothered by the presence of spiders. However, there are some other animals that I badly dislike; cockroaches, mosquitoes and flies. Something one just got to accept in warmer climates is cockroaches, they are found almost everywhere. A few times a month I find them running around inside my apartment. It’s a completely harmless beetle, but it’s a fast runner and hard to kill, even when I get a direct hit with toxic insecticide spray.
In the same way, flies and mosquitoes are harmless but annoying; Especially in some arid landscapes there are some painful weeks to expect in summer where the number of flies is extremely high, and they seem to be everywhere. Many houses and apartments often have meshed mosquito nets mounted on the outside of the door and windows to keep flying insects out of the house, as well as an insecticide spray at hand to keep the insect boom under control. I have no problem with spiders and snakes in Australia, but for me, there is barely anything worse than the buzz of mosquitoes just when I turned off the lamp ready for bed.
Whales, fish and molluscs
Out of the world’s 22,000 species of fish about 4,000 live in Australia’s seas and lakes. The world heritage listed Great Barrier Reef off Queensland north-east coast support vast numbers of colourful fish (such as the clown anemonefish from the movie finding Nemo). In this article, we look closer at life under the surface.
The whale shark (the world’s largest fish) along with families of humpback whales, right whales, orcas and many kinds of dolphins and sharks migrate or live along different Australian coastlines. Whales can be seen along the east and west coasts from May to November and the chance to see sharks are highest in north-western Western Australia.
It is not uncommon that whales, dolphins, seals and sea lions approach boats and bathers if they feel safe. Don’t miss seeing these mighty marine mammals up close if you get the opportunity. Dolphins and whales are found around Australia’s entire coastline, while spotting seals and sea lions is easiest at the mainland’s south coast, Tasmania and places like Kangaroo Island outside of Adelaide.
Orcas are found in all waters around Australia but mostly south of the mainland. Australia’s most common dolphin, bottlenose dolphin, is also found around Australia’s entire coastline but is easier to spot in the warmer northern waters. Both orcas and bottlenose dolphins are toothed whales which body type resemble each other’s.
The humpback- and right whales are baleen whales which move with the seasons between warmer seas in the north and colder waters close to the South Pole. Summers are spent in the cold waters around Antarctica where they feed on krill and plankton. In fall when water temperatures become increasingly colder and the sea begins to freeze up, the whales migrate northwards towards more pleasant water to hibernate, and in some cases to feed their cubs. Between May and August, the humpbacks migrate northwards along the east and west coast to the northern parts of Western Australia and Queensland, and between September and December they migrate back south the same route they came. Since the migration takes place close to the coast, whales can often be spotted from lookouts along the coast.
The right whale’s migration is a little different compared to the humpbacks as they don’t go as far north along the east and west coasts. Between May and November, they can be seen near the mainland’s southern coasts.
Other marine creatures to mention (and not quite as welcomed as the mammals) are the different species of jellyfish and octopus. They can be found along coastal waters where people swim and several of these species are not to joke around about. Especially two kinds of box jellyfish are hugely toxic and dangerous to humans: sea wasp and Irukandji.
Box jellyfish is, unlike ordinary jellyfish that float along with the currents, slightly mobile in the waters which enables it to catch its prey (zoo plankton and small fish). Speeds up to 6 m per minute has been measured in the box jellyfish, all thanks to its anatomy. Their nervous system is much more developed than ordinary jellyfish and they even have primitive eyes and a very simple organ resembling a brain. This makes them more than just simple blobs of jelly that follows the currents. A sting from this jellyfish is extremely painful and has in some untreated cases led to the victim’s death in as short as three minutes. The sea wasp’s bell can get as big as a basketball and its tentacles up to 3 m in fully extended condition (although they are shorter when the jellyfish isn’t hunting).
The Irukandji’s bell is very small (0.5-2 cm) with tentacles up to one metre long. It is not advisable to swim or even wade in waters where The Irukandji occur since it is virtually transparent in the water and its sting is very dangerous. Often there are meshed nets (so-called stinger nets – these types of stinging jellyfish are often called stingers) in the northern waters in the summer. It is safe to swim without getting stung behind these nets. These stingers only live in warm tropical waters during summer months. If you are south of Gladstone in Queensland, the water is safe to bathe in. From Cape York down to Townsville, the box jellyfish poses a threat to bathers From October to June each year, and south of Townsville down to Gladstone, they only occur between December and March. Sharks however can swim the waters year around.
Less dangerous but the more common all year round is the small translucent bluebottle jellyfish. Despite its name, it is not a jellyfish, but a colony of four different polyps, all of which have the same genetic origin but so specialized that they live together as a single organism. Its bell is shaped as a sail or a bottle which makes the colony float along the surface being pulled by the wind. The bell is between 5-15 cm long and its tentacles, which are full of nettle cells, usually are a few decimetres long but can reach up to 10 m. In the summer, bluebottles are particularly common along the east coast, but also found along southern Australia and parts of Western Australia.
We round off with an octopus worth knowing. The blue ring octopus which only measures 1-2 dm lives in tidal pools along reefs around Australia, especially in southern New South Wales and South Australia. Although they are small and relatively peaceful animals, you should beware of frightening them as they can sting divers and waders with a poison that potentially can kill people since there is no antidote.