Animals and Corals
The Great Barrier Reef is home to thousands of plants and animals that all contribute to its rich diversity. Holding the world's largest collection of corals (more than 400 different kinds), coral sponges, molluscs, rays, dolphins, over 1500 species of tropical fish, more than 200 types of birds, around 20 types of reptiles including sea turtles and giant clams over 120 years old. The Great Barrier reef is also breeding area for humpback whales, migrating from the Antarctic and is also the habitat of a few endangered species including the Dugong (Sea Cow) and large Green Sea Turtle.
Marine Mammals
More than 30 species of marine mammals are found along the Great Barrier Reef. Bottlenose dolphins, humpback and dwarf Minke whales are frequently seen while other species such as Bryde's whale are occasionally seen or perhaps rarely recognised. The Great Barrier Reef is also an important habitat for Dugong.
Bottlenose dolphins can reach speeds over 30 kilometers per hour. They surface often to breathe, doing so two or three times a minute. Bottlenose dolphins travel in social groups and communicate with each other by a complex system of squeaks and whistles.
Bottlenose dolphins track their prey though the expert use of echolocation. They can make up to 1,000 clicking noises per second. These sounds travel underwater until they encounter objects, then bounce back to their dolphin senders, revealing the location, size, and shape of their target.
When dolphins are feeding, that target is often a bottom-dwelling fish, though they also eat shrimp and squid. These clever animals are also sometimes spotted following fishing boats in hope of dining for leftovers.
Bottlenose dolphins are found in tropical oceans and other warm waters around the globe. They were once widely hunted for meat and oil (used for lamps and cooking), but today only limited dolphin fishing occurs. However, dolphins are threatened by commercial fishing for other species, like tuna, and can become mortally entangled in nets and other fishing equipment.
Bottlenose dolphins track their prey though the expert use of echolocation. They can make up to 1,000 clicking noises per second. These sounds travel underwater until they encounter objects, then bounce back to their dolphin senders, revealing the location, size, and shape of their target.
When dolphins are feeding, that target is often a bottom-dwelling fish, though they also eat shrimp and squid. These clever animals are also sometimes spotted following fishing boats in hope of dining for leftovers.
Bottlenose dolphins are found in tropical oceans and other warm waters around the globe. They were once widely hunted for meat and oil (used for lamps and cooking), but today only limited dolphin fishing occurs. However, dolphins are threatened by commercial fishing for other species, like tuna, and can become mortally entangled in nets and other fishing equipment.
Birds, Seabirds and Shorebirds
Islands and cays along the Great Barrier Reef are home to approximately 215 species of bird and support breeding populations of 24 seabird species. Areas of international significance for migratory and resident species of shorebirds are found on or next to the Great Barrier Reef. Apart from human disturbance, natural pressures such as storms and cyclones also affect seabird populations. These natural disasters can be massive; however can be tolerated because they are not regular.
Wedge-tailed shearwaters are one of several species, known as 'mutton-birds', whose chicks are harvested as food by Indigenous people in Australia and New Zealand. Shearwaters spend their whole life at sea, except when breeding. Like their close relatives, the albatrosses and petrels, they live almost constantly on the wing.
The distinguishing feature of shearwaters is their tube-nosed bill, which is long and slightly hooked at the tip with two nostrils that appear as a double tube at the base of the upper mandible. Shearwaters obtain essential moisture by drinking seawater. The tube nose enables shearwaters to expel excess salt from their bodies.
Shearwaters eat crustacewans, organic plankton, squid, fish, and in some cases floating scraps discarded from fishing boats. Great care should be taken when visiting shearwater breeding islands. The ground may be honey-combed with burrows, and it is easy to break a leg or crush eggs by sinking through the ground into a burrow by mistake. Some birds are easily frightened and may desert their nest with eggs and chicks.
The distinguishing feature of shearwaters is their tube-nosed bill, which is long and slightly hooked at the tip with two nostrils that appear as a double tube at the base of the upper mandible. Shearwaters obtain essential moisture by drinking seawater. The tube nose enables shearwaters to expel excess salt from their bodies.
Shearwaters eat crustacewans, organic plankton, squid, fish, and in some cases floating scraps discarded from fishing boats. Great care should be taken when visiting shearwater breeding islands. The ground may be honey-combed with burrows, and it is easy to break a leg or crush eggs by sinking through the ground into a burrow by mistake. Some birds are easily frightened and may desert their nest with eggs and chicks.
Marine Turtles
Six of the worlds seven species of marine turtle inhabit the Great Barrier Reef; significant global areas for nesting for four of these turtles are found in the region. All six species of turtle are classified as threatened as a result of pressures both from within the Great Barrier Reef and elsewhere.
The Green Turtle's smooth, high-domed shell is mottled olive green, brown and black, but the species actually gets its name from the colour of its fat. The turtle was once hunted in Australia for its eggs and meat which were boiled into soup until it was given legal protection in 1973. Adults have shell length of about 1 m and average about 130 kg, although some nesting females can weigh more than 180 kg.
The Green Turtle lives around coral and rocky reefs and seagrass meadows in tropical and subtropical seas. The turtles live here for decades, grazing on seagrass, seaweed and jellyfish before making their first migration back to their birthplace to breed.
The Green Turtle is an endangered species. Crabs, goannas, herons, gulls, foxes and fish such as sharks all make a meal of hatchlings. Tiger sharks also snap up juvenile and adult turtles. But the greatest threat facing green turtles is human disturbance to their feeding and nesting areas. Each year turtles drown in fishing gear and are strangled or choked by rubbish. Dredging (the removal of sediment from the sea floor to make a channel deep enough for larger boats) can damage the turtles’ seagrass beds. Coastal developments such as marinas and high-rise buildings can also disturb turtles’ nesting beaches. And in many countries, hunting has drastically reduced the turtle population. The green turtle is protected in Australian waters, and in Shark Bay, hunting is restricted to traditional use by Aboriginal people.
The Green Turtle lives around coral and rocky reefs and seagrass meadows in tropical and subtropical seas. The turtles live here for decades, grazing on seagrass, seaweed and jellyfish before making their first migration back to their birthplace to breed.
The Green Turtle is an endangered species. Crabs, goannas, herons, gulls, foxes and fish such as sharks all make a meal of hatchlings. Tiger sharks also snap up juvenile and adult turtles. But the greatest threat facing green turtles is human disturbance to their feeding and nesting areas. Each year turtles drown in fishing gear and are strangled or choked by rubbish. Dredging (the removal of sediment from the sea floor to make a channel deep enough for larger boats) can damage the turtles’ seagrass beds. Coastal developments such as marinas and high-rise buildings can also disturb turtles’ nesting beaches. And in many countries, hunting has drastically reduced the turtle population. The green turtle is protected in Australian waters, and in Shark Bay, hunting is restricted to traditional use by Aboriginal people.
Crocodile
The Saltwater Crocodile can be found in most coastal waters and around many of the islands and cays of the Great Barrier Reef.
The Saltwater Crocodile is the world's largest reptile. These amazing creatures are found on the northern coast of Australia and inland for up to 100 kms or more. The Saltwater Crocodile has been reported to grow to lengths of 7 metres, but the average size of the Saltwater Crocodile is 4 metres long.
The Saltwater Crocodile is usually found in deep, dark murky water. It may inhabit fresh or saltwater but it is most commonly found in the brackish estuary areas of Northern Australia. Saltwater Crocodiles take a wide variety of prey, although juveniles are restricted to smaller items such as insects, amphibians, crustaceans, small reptiles and fish. The larger the animal becomes, the larger its prey items are.
Around breeding season, which usually takes place during the wet season, large male crocodiles will patrol their stretches of water protecting their territory from intruding males. When Saltwater Crocodiles are courting one another, they will rib their heads and bodies together. Mating takes place in the water. Between 4-6 weeks after mating, the female will lay 40-60 eggs in her nest. The nest may be up to 80 cm high and is made of vegetation broken off by the female's teeth and scraped together with her hind legs.
The Saltwater Crocodile is usually found in deep, dark murky water. It may inhabit fresh or saltwater but it is most commonly found in the brackish estuary areas of Northern Australia. Saltwater Crocodiles take a wide variety of prey, although juveniles are restricted to smaller items such as insects, amphibians, crustaceans, small reptiles and fish. The larger the animal becomes, the larger its prey items are.
Around breeding season, which usually takes place during the wet season, large male crocodiles will patrol their stretches of water protecting their territory from intruding males. When Saltwater Crocodiles are courting one another, they will rib their heads and bodies together. Mating takes place in the water. Between 4-6 weeks after mating, the female will lay 40-60 eggs in her nest. The nest may be up to 80 cm high and is made of vegetation broken off by the female's teeth and scraped together with her hind legs.
Sea Snakes
The Great Barrier Reef is home to 14 different species of sea snake. This high number of different species is largely due to the Marine Park's variety of suitable habitat.
Sea snakes are venomous snakes that live in the water for most or all of their lives. Though they evolved from terrestrial ancestors, most are adapted to aquatic life completely and they cannot move on land, except for one genus (Laticauda), which still has some characteristics from its ancestors and can therefor move on land limitedly.
Sea snakes are found in the warm coastal waters of the Pacific and Indian Ocean. All species a have paddle-like tail and almost all of them have lateral compressed bodies which make them look like eels. They don't have gills though, so they have to come up to the surface once and a while to breathe. Nevertheless, they are among the most completely aquatic of all air-breathing vertebrates. Among this group are species that are listed as the most venomous of all snakes. Some are quite gentile and bite only when they are provoked, while others are much more aggressive.
A few species of sea snakes feed on fish, especially eels. A few others feed only on fish eggs, which is quite unusual for a venomous snake. One species prefers mollusks and crustaceans.
Sea snakes are found in the warm coastal waters of the Pacific and Indian Ocean. All species a have paddle-like tail and almost all of them have lateral compressed bodies which make them look like eels. They don't have gills though, so they have to come up to the surface once and a while to breathe. Nevertheless, they are among the most completely aquatic of all air-breathing vertebrates. Among this group are species that are listed as the most venomous of all snakes. Some are quite gentile and bite only when they are provoked, while others are much more aggressive.
A few species of sea snakes feed on fish, especially eels. A few others feed only on fish eggs, which is quite unusual for a venomous snake. One species prefers mollusks and crustaceans.
Sharks and Rays
133 species of shark and rays are found along the Great Barrier Reef and range from the small Epaulette shark to the large migratory species such as the whale shark.
Epaulette sharks have small, slightly flattened, elongated bodies that allow them to swim between coral branches and wriggle into narrow reef crevices. They have a swollen snout that is longer than that of any other hemiscyllidae shark and nasal barbels. The two relatively large, spineless dorsal fins are about the same size. The anal fin, far back on the underside, is in front of the caudal fin, and separated from it by a notch. These short. stubby, paired fins are used by many species for "walking" across the bottom. The dorsal and anal fins are set back on an extremely long thick tail. The maximum length of the species is about 3.6 feet.
Epaulette sharks are nocturnal ( hunt at night ) and feed mainly on small benthic invertebrates (worms, crab, shrimp and small shellfish ), possibly also small fishes. When eating animals with hard shells, the shark's spiky, sharp teeth flatten to form crushing plates. At night it roams the reef flats using its muscular leg-like paired fins to clamber about the reef and into crevices looking for prey. The epaulette shark has the amazing ability to survive low oxygen conditions by switching off non-essential brain functions; this is apparently an adaption for hunting in tide pools with low oxygen. When hunting buried prey it will shove its rostrum deep into the sand and move it slightly from side to side. Presumably, the nasal barbels have a sensory function. If so the shark could locate worms and crustaceans hiding under the sand by contacting them with the barbels. The epaulette shark may hunt cryptic prey within the staghorn coral beds by day and moves out to hunt in more exposed areas at night. The
Epaulette sharks are nocturnal ( hunt at night ) and feed mainly on small benthic invertebrates (worms, crab, shrimp and small shellfish ), possibly also small fishes. When eating animals with hard shells, the shark's spiky, sharp teeth flatten to form crushing plates. At night it roams the reef flats using its muscular leg-like paired fins to clamber about the reef and into crevices looking for prey. The epaulette shark has the amazing ability to survive low oxygen conditions by switching off non-essential brain functions; this is apparently an adaption for hunting in tide pools with low oxygen. When hunting buried prey it will shove its rostrum deep into the sand and move it slightly from side to side. Presumably, the nasal barbels have a sensory function. If so the shark could locate worms and crustaceans hiding under the sand by contacting them with the barbels. The epaulette shark may hunt cryptic prey within the staghorn coral beds by day and moves out to hunt in more exposed areas at night. The
Fish
Around 1625 of bony fish species including important commercial species such as coral trout are found on the Great Barrier Reef.
Coral trout belong to a family of fish known as the Serranidae. This family includes groupers and cods which are all characterised by having three spines on the gill cover and a large mouth lined with more than one row of teeth.
Coral trout are voracious fish eating predators (piscivores). Younger juvenile trout mostly eat crustaceans, especially prawns which live on or near the reef bottom. Adult coral trout feed upon a wide diversity of reef fish. The most common type of fish eaten is Damselfish (Family Pomacentridae), and the Spiny Chromis Damselfish (Acanthochromis polyacanthus) seems to be the favourite. Adult coral trout also eat juvenile coral trout. Individual fish usually feed once every 1-3 days, although some fish sometimes go for many days without feeding. A total of 90% of a single prey item will be digested within 24 hours.
The Common Coral Trout occurs in tropical marine waters of the Indo-West Pacific. In Australia it is known from north-western Western Australia, around the tropical north and south to the southern Great Barrier Reef, Queensland. - See more at: http://australianmuseum.net.au/Common-Coral-Trout-Plectropomus-leopardus/#sthash.ozzOoPkT.dpuf
Coral trout are voracious fish eating predators (piscivores). Younger juvenile trout mostly eat crustaceans, especially prawns which live on or near the reef bottom. Adult coral trout feed upon a wide diversity of reef fish. The most common type of fish eaten is Damselfish (Family Pomacentridae), and the Spiny Chromis Damselfish (Acanthochromis polyacanthus) seems to be the favourite. Adult coral trout also eat juvenile coral trout. Individual fish usually feed once every 1-3 days, although some fish sometimes go for many days without feeding. A total of 90% of a single prey item will be digested within 24 hours.
The Common Coral Trout occurs in tropical marine waters of the Indo-West Pacific. In Australia it is known from north-western Western Australia, around the tropical north and south to the southern Great Barrier Reef, Queensland. - See more at: http://australianmuseum.net.au/Common-Coral-Trout-Plectropomus-leopardus/#sthash.ozzOoPkT.dpuf
Echinoderms
There are about 630 species recorded along the Great Barrier Reef, with starfish perhaps being the most well known.
The feather starfish use this arms to filter the food from the passing currents and then pass it down to there mouth. Very different from the traditional starfish that feeds from the bottom and moves along the ground to feed. The feather star has “feet” called cirri that is uses to append itself to fan coral, or other perches where it can feed from a nice passing current.
They also have many more then the traditional 5 arms associated with a starfish. The amount of arms depend on the species and health of the starfish, most species have around 20 arms while some can have over 200. These arms are covered with a sticky substance which it uses to help catch the passing food and pass it down the stars mouth. It is important not to handle these stars as you can severely disrupt their feeding if they are man-handled.
They also have many more then the traditional 5 arms associated with a starfish. The amount of arms depend on the species and health of the starfish, most species have around 20 arms while some can have over 200. These arms are covered with a sticky substance which it uses to help catch the passing food and pass it down the stars mouth. It is important not to handle these stars as you can severely disrupt their feeding if they are man-handled.
Crustaceans
Around 1300 species, including a number that are commercially important (for example, some species of crabs and prawns).
Crustaceans are defined by having a body covered with a protective shell composed of a horny substance called chiton. This material acts as an external skeleton and is very strong. To enable mobility, the shell has many divisions called “somites”, which allows flexibility.
Crustaceans have a number of jointed legs, two pairs of antennae and often a pair of ‘nippers’. The body has three parts: a head, a middle region (thorax) and a tail region (abdomen). Often the head and thorax are joined together and covered by a single shell called a carapace (such as in the local mud crabs).
Most crustaceans are nocturnal (active at night), and spend the day buried in the sand, or hiding under coral ledges. They feed on a wide variety of food, including plant and animal matter, and some will feed on detritus alone.
Due to their outer shell, they have developed a cunning strategy to grow. When the inside soft tissue has filled out the outer shell, the animal will “break out” of its confines and lie low for a few days until its new shell has hardened. This process is called ecdysis. If a crustacean should happen to lose a limb or claw (which happens often when they are fighting over territory), they have an amazing ability to regrow a new one.
Crustaceans have a number of jointed legs, two pairs of antennae and often a pair of ‘nippers’. The body has three parts: a head, a middle region (thorax) and a tail region (abdomen). Often the head and thorax are joined together and covered by a single shell called a carapace (such as in the local mud crabs).
Most crustaceans are nocturnal (active at night), and spend the day buried in the sand, or hiding under coral ledges. They feed on a wide variety of food, including plant and animal matter, and some will feed on detritus alone.
Due to their outer shell, they have developed a cunning strategy to grow. When the inside soft tissue has filled out the outer shell, the animal will “break out” of its confines and lie low for a few days until its new shell has hardened. This process is called ecdysis. If a crustacean should happen to lose a limb or claw (which happens often when they are fighting over territory), they have an amazing ability to regrow a new one.
Molluscs
More than 3000 species known from the Great Barrier Reef. This group includes clams, oysters, squid, octopus, cuttlefish, nautilus, nudibranchs, chitons and snails.
Octopuses have dispensed with shells altogether, except for the related female Argonaut, which produces a nautilus-like shell as an egg capsule. Although the octopus cannot jet around quickly if necessary they prefer to walk on their eight arms and lurk inconspicuously in rock and coral crevices. Like squids they are able to squirt black ink into the water creating a visual, and possibly scent, screen while they make a swift escape. Both animals can also change colour, to camouflage themselves or to communicate.
The blue ringed octopus is a small mollusk organism that could fit into the palm of your hand. Killed by way of fear or harvested for one or both of its powerful muscular- neurotoxins, this deceptive little critter produces a potent toxin known as Tetrodotoxin, which is uses in self-defence. Tetrodotoxin is also found in pufferfish and cone snails. This toxin is actually produced by bacteria that live in the salivary glands of the octopus.
The blue ringed octopus is a small mollusk organism that could fit into the palm of your hand. Killed by way of fear or harvested for one or both of its powerful muscular- neurotoxins, this deceptive little critter produces a potent toxin known as Tetrodotoxin, which is uses in self-defence. Tetrodotoxin is also found in pufferfish and cone snails. This toxin is actually produced by bacteria that live in the salivary glands of the octopus.
Hard Corals
The signature group of the Great Barrier Reef with more than 450 species known.
Hard corals act as building blocks for the Reef. They form when colonies of coral polyps produce limestone skeletons to support themselves.
In most cases, a hard coral consists of hundreds, thousands or even millions of individual coral polyps living together as a colony.They have six (or multiples of six) smooth tentacles.
Common types of hard coral on the Reef include brain coral and staghorn coral.
In most cases, a hard coral consists of hundreds, thousands or even millions of individual coral polyps living together as a colony.They have six (or multiples of six) smooth tentacles.
Common types of hard coral on the Reef include brain coral and staghorn coral.
Soft Corals and sea pens
At least 150 species known from the Great Barrier Reef. With their swaying bodies and jelly like feel, soft corals bodies are made up of a large number of polyps connected by fleshy tissue.
Soft corals are flexible because they lack a solid skeleton which means they are often mistaken for plants.
Instead they are supported by tiny limestone spike-like structures called spicules.
Apart from their swaying bodies and jelly-like feel, soft corals also have eight tentacles on each polyp. The tentacles have a feathery appearance, whereas hard corals have smooth tentacles.
A number of animals, such as different species of fish, prawns and sea slugs, like to make their home in the branches of soft corals. Often, these animals are camouflaged by having the identical colour pattern to the soft coral that they live on.
Soft corals are always in danger of being eaten by other animals such as fish, snails and crustaceans. They fight back by producing chemicals in their tissues that make them distasteful or even poisonous to those animals. Soft corals also have spiky spicules which function like thorns on a rose bush.
Instead they are supported by tiny limestone spike-like structures called spicules.
Apart from their swaying bodies and jelly-like feel, soft corals also have eight tentacles on each polyp. The tentacles have a feathery appearance, whereas hard corals have smooth tentacles.
A number of animals, such as different species of fish, prawns and sea slugs, like to make their home in the branches of soft corals. Often, these animals are camouflaged by having the identical colour pattern to the soft coral that they live on.
Soft corals are always in danger of being eaten by other animals such as fish, snails and crustaceans. They fight back by producing chemicals in their tissues that make them distasteful or even poisonous to those animals. Soft corals also have spiky spicules which function like thorns on a rose bush.