Explore life on the coral life and learn more about the taxonomy, behaviour and threats facing those living things that have the reef as their home.
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Kingdom Animal (Animalia)
Phylum Chordate (Chordata)
Class Bony fish (Osteichthyes)
Species Bolbometopon muricatum
This distinctive fish has a vertical forehead and huge teeth for ramming into and then eating corals, and is also sometimes called the humpheaded or double-headed parrotfish. They grow slowly and can live for up to 40 years. They are found in groups, and sleep as groups too, often in the shelter of caves or shipwrecks.
Size: They grow to over 1m in length.
Feeding: They live off algae and live corals, eating over 5 tonnes a year, and are primarily hunted by sharks, as well as humans.
Habitat: Bumphead parrotfish live around reefs and lagoons of the Indian and Pacific oceans, to a depth of around 30m.
Threats: They face no specific threats other than those that face the coral reef ecosystem in general, but can suffer from overfishing.
XL Catlin Seaview Survey
Kingdom Animal (Animalia)Phylum Chordate (Chordata)Class Bony fish (Osteichthyes)Species Scarus psittacus
The parrotfish is a common sight on the fore reef in many areas of the Great Barrier Reef. Parrotfish play an important role on the coral reef by keeping down algal growths and creating the conditions for a healthy reef. They get their name from their distinctive 'beak' and the sound of their scraping the reef for food is very distinctive.
Size: They grow to between 30cm and 60cm.
Feeding: They live off algae growing on the reef and are primarily hunted by sharks, as well as humans.
Habitat: Parrotfish live around reefs and lagoons of the Indian and Pacific oceans as well as the Caribbean, to a depth of around 30m.
Threats: With declining numbers of commonly hunted species such as snapper, the parrotfish is being harmed by overfishing in many regions.
Kingdom Animal (Animalia)Phylum Arthropod (Arthropoda)Class Crustacean (Crustacea)Subclass Copepoda
A copepod is a small marine animal. It is a crustacean, and is related to lobsters, shrimps and crabs. Copepods are plankton, animals (zooplankton) and plants (phytoplankton) that are carried by ocean currents rather than making their own way in the world. The word copepod comes from two Greek words kope- oar and pod- foot. These are the oar-footed creatures and they are the most abundant animal on this planet.
Size: Copepods are typically 1mm to 2mm long.
Feeding: Copepods are essential for the marine food chain. They are secondary producers, eating algae and turning this into the more complex building blocks needed for larger marine life, such as filter feeders.
Habitat: Throughout the oceans from pole to pole.
Threats: Copepods are susceptible to a decrease in the pH of the oceans from the process of ocean acidification.
Wikipedia / Uwe Kils
Kingdom Animal (Animalia)Phylum Chordate (Chordata)Class Sharks & rays (Chondrichthyes)Species Mobula alfredi
Mantas are large graceful fish, that often look like they are flying through the water with their large pectoral fins. They are filter feeders, using lobes either side of their mouth to funnel plankton towards them. Mantas are often found visiting cleaning stations, where fish such as the cleaner wrasse nibble parasites and dead skin found on the manta's gills and skin.
Size: Reef mantas reach 5.5 metres wide.
Feeding: Mantas are filter feeders, eating plankton and fish larvae. The mantas main predators are large sharks and orcas (killer whales).
Habitat: Typically found throughout tropical and subtropical waters.
Threats: They are slow swimmers near the surface and often become entangled in fishing gear.
Kingdom Animal (Animalia)Phylum CnidariaClass AnthozoaSpecies Acropora cervicornis
Staghorn coral is a branching stony coral. Such hard corals are actually colonies of tiny polyps, a small animal much like the sea anemone. The polyps form a carbonate shelter and as the polyps reproduce asexually, these carbonate structures grow as long branches. Hard corals are essential in creating the 3D reef habitat that supports so many different species.
Size: Branches range from a few centimetres to over 2m.
Feeding: Hard corals receive energy from their symbiotic relationship with zooxanthellae. The polyps also catch plankton such as copepods.
Habitat: Back and fore reef habitats at a depth of 0-30m.
Threats: Staghorn coral is susceptible to damage from changes in salinity, pH level and sediment in the water and especially from increases in sea temperature which can cause bleaching. Locally, threats include storm damage and being eaten by the crown-of-thorns starfish.
Kingdom Animal (Animalia)Phylum Chordate (Chordata)Class Bony fish (Osteicthyes)Species Cheilinus undulatus
The Maori wrasse is one of the largest reef fish and the largest of the wrasse family. They are voracious predators, eating anything from molluscs to echinoderms and crustaceans, as well as small fish. They are one of the few species to eat the Crown-of-thorns starfish.
Size: They can grow up to 2m in length.
Feeding: They feed on molluscs, crustaceans and echinoderms. They have few natural predators.
Habitat: Reefs throughout the Indian and Pacific oceans, from the shallows to a depth of 100m.
Threats: They are vulnerable to overfishing and pollution, e.g. cyanide fishing.
Kingdom Animal (Animalia)Phylum Arthropod (Arthropoda)Class Crustacean (Crustacea)Order Stomatopoda
Mantis shrimps are marine crustaceans. They are aggressive and typically solitary creatures. They kill their prey in two different ways, by spearing or smashing with their large front claws. Some species are 'spearers' impaling their prey and other are 'smashers', striking their victims and stunning or killing them. Their smash is so powerful and fast it can create a sonic boom and there are reports of mantis shrimps kept in aquaria breaking the glass.
Size: Mantis shrimps grow to between 1cm and 40cm long.
Feeding: 'Spearers' prefer animals without a hard shell such as small fish. 'Smashers' prey on crabs, snails and other molluscs. They are preyed upon by larger fish.
Habitat: Mantis shrimps live in crevices in the coral or rock in lagoons and also burrow in the sand.
Threats: They face no known threats, except those that threaten the coral reef ecosystem as a whole.
Kingdom Animal (Animalia)Phylum Chordate (Chordata)Class Sharks & rays (Chondrichthyes)Species Galeocerdo cuvier
One of the largest sharks in the world, the tiger shark is one of the apex predators on the Great Barrier Reef. It gets its name from the dark vertical stripes along its sides that resemble a tiger's stripes. It is a solitary creature, mainly hunting at night.
Size: Adult tiger sharks commonly grow to between 3m and 4.2m long, and can grow over 5m in length.
Feeding: They are voracious predators and not very picky, eating anything from fish to turtles, squid, marine mammals, human rubbish and car number plates.
Habitat: Mainly throughout tropical and subtropical waters worldwide, and are often found close to the coast.
Threats: They are vulnerable to fishing due to their slow growth and long lifespan.
Kingdom Animal (Animalia)Phylum Echinoderm (Echinodermata)Class Holothuroidea
Sea cucumbers are a diverse and common type of echinoderm, found all along the Great Barrier Reef. Amongst sea cucumbers, a number of species have some quite surprising habits. Many sea cucumbers reproduce asexually, splitting in half to form two complete individuals. A favourite defence mechanism to avoid being eaten by fish, is to shoot their guts and internal organs out of their anus. This photo shows the same sea cucumber mirrored, breathing in and out through its anus.
Size: Adults typically range from 10cm to 30cm in length.
Feeding: Most sea cucumbers sift through the sediment for plankton and decaying organic matter. They are eaten by a range of fish.
Habitat: Found on coral reefs, the intertidal zone and in deep water.
Threats: Edible species of sea cucumber (yes - they are widely considered delicious!), known as beche-de-mer are under threat from overfishing.
Kingdom Protist (Protista)Phylum Brown algae (Phaeophyta)Class PhaeophyceaeGenus Sargassum
Sargassum includes some of almost 2,000 species of brown algae. It is a type of seaweed which grows thickly, attached to rocks in shallow waters as well as floating with the ocean currents (known as 'planktonic'). Its fronds have small globe-shaped compartments filled with gas. This helps it float near the sea's surface to enable photosynthesis. It plays a dual role by helping to form habitats as well as providing a food.
Size: A few centimetres to up to 12 metres in warmer waters.
Feeding: It absorbs sunlight through photosynthesis and is eaten by smaller, herbivorous fish and sea urchins.
Habitat: Temperate and tropical waters
Threats: Pollution can affect their ability to build proteins.
Wikipedia / Graça Gaspar
Kingdom Protist (Protista)Phylum Red algae (Rhodophyta)Class RhodophyceaeGenus Porolithon
Porolithon are pinkish algae which build and strengthen coral reefs. They live on rock, binding materials together and forming a calcified layer beneath them to protect the reef crest from the impact of waves and storms, and are known as 'reef cement'. They also convert nutrients into food for other species and generate oxygen.
Size: From microscopic up to 25cm.
Feeding: They absorb sunlight through photosynthesis and provide a food source for smaller, herbivorous fish.
Habitat: Primarily reef crests, as well as the inner and outer reef, in warm and tropical waters.
Threats: They are under threat from ocean acidification which makes it harder for the formation of their carbonate structures. Pollution and higher water temperatures also have an impact.
Kingdom Animal (Animalia)Phylum Chordate (Chordata)Class Bony fish (Osteichthyes)Genus Labroides
Cleaner wrasses are fish which specialise in cleaning other, larger fish. This symbiotic relationship allows larger fish to stay clean, and provides a food source for the wrasse. The cleaner wrasses congregate in 'cleaning' areas, where bigger fish visit to be groomed by the wrasses, which swim into their mouths and gills to ensure everything is clean. They are also capable of changing sex.
Size: Most species of cleaner wrasse are small, no bigger than 20cm long.
Feeding: They feed off the dead tissue and parasites of the fish they clean but have few predators, as larger fish prefer the longer term benefits of cleaning rather than a quick snack!
Habitat: They live mainly around coral reefs of the Indian and Pacific oceans, as well as in South East Asia and around the Red Sea.
Threats: They face no specific threats except those that threaten the coral reef ecosystem as a whole.
Kingdom Animal (Animalia)Phylum Chordate (Chordata)Class Bony fish (Osteichthyes)Family Carapidae
Pearlfish are tiny fish which live inside invertebrates, including starfish, clams and sea cucumbers. They enter their host's body cavity via their anus and live there, protected from predators and with a ready source of nutrients. Most species of pearlfish live at peace with their host, but others are parasitic, eating them. They have translucent bodies, and tend to go hunting for prey at night.
Size: From a few centimetres long to 20cm.
Feeding: Small invertebrates and crustaceans, or some feed off the organs of their host. They are eaten by larger fish.
Habitat: They live in tropical waters of the Atlantic, Indian and Pacific oceans, to a depth of 2,000m but more usually in shallow waters of less than 30m.
Threats: They face no specific threats other than those that face the coral reef ecosystem in general.
Kingdom Animal (Animalia)Phylum Chordate (Chordata)Class Bony fish (Osteichtheyes)Species Amphiprion ocellaris
There are 30 different species of anemonefish, so called as they have a symbiotic relationship with anemones. The anemone provides shelter from predators and provides the fish with a food source. The fish protect the anemone from predators, as well as provide it with nutrients from waste matter. Anemonefish are born as males and become female as they mature.
Size: Typically between 10cm-20cm long.
Feeding: They eat zooplankton such as copepods, and are hunted by larger fish.
Habitat: Shallow reefs and lagoons of the Indian and Pacific oceans, including the Great Barrier Reef and Red Sea.
Threats: Anemonefish are popular aquarium fish. The release of the Disney film 'Finding Nemo' in 2003 saw a sharp increase in demand which saw false clownfish populations decline.
Kingdom Animal (Animalia)Phylum Mollusc (Mollusc)Class Gastropod (Gastropoda)Order Nudibranchia
Nudibranchs are a type of mollusc and some of the most colourful animals on the Great Barrier Reef. Often referred to as 'sea slugs', these animals have a variety of different defence mechanisms to avoid being eaten, from storing poisonous cells from anemones they eat, to camouflage and also appearing as bright and colourful as possible to scare of would-be predators.
Size: Nudibranchs range from 2cm to 60cm long.
Feeding: Nudibranchs eat sea anemones and jellyfish. Some species are also cannibalistic. They are eaten by large fish such as wrasse.
Habitat: They live in the warm shallows of coral reefs.
Threats: They can be threatened by eutrophication caused by run-off from coastal areas, as well as fishing techniques such as dredging and bottom trawling.
Kingdom Animal (Animalia)Phylum Segmented worms (Annelida)Class PolychaetaSpecies Spirobranchus corniculatus
Christmas tree worms are a type of worm known as polychaetes. This refers to the little 'chaeta' or feet they have along their sides. The distinctive feature of the Christmas tree worm is the two crowns shaped like Christmas trees. These are used to strain the water for small particles of food, which are then transported in mucus to the mouth at the base of the crown.
Size: Christmas tree worms have a huge range of size from a few millimetres up to 3 metres.
Feeding: Christmas tree worms filter the seawater for plankton. They are eaten mainly by fish
Habitat: The Christmas tree worm larvae settle on damaged coral polyps and create a burrow. Preference is shown for large coral 'bommies' or mounds.
Threats: Because of their dependence on live coral, anything that threatens the coral, impacts Christmas tree worms.
Kingdom Animal (Animalia)Phylum Chordate (Chordata)Class Reptile (Reptilia)Species Chelonis mydas
Green turtles are one of the six species of sea turtle that are found on the Great Barrier Reef. In the non-breeding season, turtles from the Great Barrier Reef travel as far as Fiji and Indonesia. Green turtles lay their eggs in pits they dig on beaches on islands and cays. Female turtles return to the beaches where they hatched to lay their eggs.
Size: Adult green turtles usually have a carapace (shell) between 80cm and 120cm long.
Feeding: Green turtles feed mainly on algae and seagrass. They are eaten by humans and larger sharks.
Habitat: Green turtles are found throughout tropical and subtropical oceans, returning to beaches to nest and they feed on coral reefs and seagrass meadows.
Threats: Green turtles face a number of human impacts, from being caught in fishing nets to having their nesting sites destroyed by developments. They can also be killed by boat strikes.
Kingdom Animal (Animalia)Phylum CnidariaClass AnthozoaOrder Actiniaria
Anemones are a type of polyp, the same animal that forms corals. They are usually found as single polyps, but can also form colonies. They have tentacles formed around an oval body which have stinging capsules, nematocysts, at their ends, to immobilise their prey. They have a symbiotic relationship with some species of fish, which use the anemones as a refuge and are not stung. In return, these fish protect the anemone from predators.
Size: Anemones range from 1cm across to over 1m in diameter.
Feeding: Sea anemones eat small fish and shrimp. They are eaten by nudibranchs, some sea stars and fish.
Habitat: They usually live on the hard bottom of the sea and are found in most tropical and temperate coastal areas.
Threats: There are no known threats to sea anemones other than the general threats to the coral ecosystem. It can be affected by outbreaks of the crown-of-thorns starfish, when they have run out of hard coral to eat.
Kingdom Animal (Animalia)Phylum Echinoderm (Echinodermata)Class Sea star (Asteroidea)Species Acanthaster planci
The crown-of-thorns starfish is one of the most studied echinoderms on the Great Barrier Reef, because of the effects that periodic population outbreaks have on coral reefs. It is an unusual species in that it is a specialist corallivore. Outbreaks can result in coral cover being reduced to below 1-5%. The outbreaks end when there is no more coral to eat. Some outbreaks occur due to increased nutrients being washed into the sea from nearby farmland.
Size: Adults are usually 20cm to 40cm in diameter.
Feeding: Crown-of-thorns starfish feed on hard corals and occasionally soft corals and anemones. They are eaten by few species, such as the trigger fish and a marine snail, Triton's trumpet.
Habitat: Coral reefs.
Threats: There are no known threats to the crown-of-thorns starfish, but populations die out when they run out of food.
Kingdom Animal (Animalia)Phylum Mollusc (Mollusca)Class Gastropod (Gastropoda)Species Charonia tritonis
Triton's trumpet is a large predatory sea snail. This mollusc is one of the few species that eats the crown-of-thorns starfish, as it has become immune to its toxins. One of the largest sea snails, they also feed on other starfish and sea urchins. They immobilise their prey by injecting them with a paralysing agent in their saliva.
Size: Adults grow to between 10cm and 35cm long.
Feeding: Triton's trumpet feeds on sea urchins and starfish.
Threats: Like all organisms with a carbonate structure or shell, Triton's trumpet can be affected by ocean acidification. In some areas, the collection of shells for ornaments can be a threat.
Kingdom Animal (Animalia)Phylum CnidariaClass AnthozoaFamily Poritidae
Poritidae is a family of hard corals that can form these large coral mounds, known as 'bommies'. Such hard corals are actually colonies of tiny polyps, a small animal much like the sea anemone. The polyps form a carbonate shelter and as the polyps reproduce asexually, these carbonate structures grow. Hard corals are essential in creating the 3D reef habitat that supports so many different species. They grow very slowly at a rate of 1-2cm a year.
Size: These mounds can range up to 8m high and 5m across.
Feeding: Hard corals receive energy from their symbiotic relationship with zooxanthellae. The polyps also catch plankton such as copepods with their stinging tentacles.
Habitat: The 'bommies' favour lagoons and proximity to the reef slope.
Threats: Hard corals are susceptible to damage from changes in pH level and especially from increases in sea temperature which can cause bleaching. Locally threats include pollution from run-off and being eaten by the crown-of-thorns starfish.
Kingdom Bacteria (Monera)Phylum Cyanobacteria
Cyanobacteria are microorganisms, bacteria which fix nitrogen and carbon. They also produce oxygen through photosynthesis, enabling other species to live in the surrounding environment. Some live within protists (e.g. algae) or sponges, providing energy to the host, or form part of lichens in the slpash zone of rocky shore environments.
Size: Microscopic, although in aquatic environments can creat 'blooms' which can be seen from space!
Feeding: They obtain energy from the sun through photosynthesis. They supply nutrients to other forms of algae and form an important part of the food web.
Habitat: All land and aquatic environments across the entire planet.
Wikipedia / Matthewjparker - Eigenes Werk
Kingdom Animal (Animalia)Phylum Echinoderm (Echinodermata)Class Sea Urchin (Echinoidea)
Sea urchins are a type of echinoderm, related to starfish and sea cucumbers. Most sea urchins hide during the day to avoid predators. They also have poisonous spines to protect them. Sea urchins are mainly herbivorous eating the algae that grows on the coral reef. They play an important role in making sure that the coral reef is not overrun by seaweed.
Size: Adults typically range from 6cm to 12cm in diameter, not including the spines.
Feeding: Most sea urchins eat algae. They are preyed upon by snails such as Triton's trumpet and also by some crabs, rays and sharks.
Habitat: Found on coral reefs, sand flats and seagrass beds.
Threats: Sea urchin larvae are extremely sensitive to ocean acidification as well as threats to the coral ecosystem.