Outforia Quicktake: Key Takeaways
- Coral reefs are diverse ecosystems that house various marine life, providing shelter, food, and breeding grounds.
- Almost 25% of marine life depends on coral reefs; some examples of coral reef animals include corals, day octopus, red-banded coral shrimp, zebra moray, and green sea turtle.
- Coral reefs develop in warm shallow waters with an ideal temperature of 75°F (24°C) and can be found in more than 100 countries.
- The Great Barrier Reef, located off northeast Australia’s coast, is the world’s largest coral reef covering 133,000 sq miles (344,468 sq km) and is home to at least 9,000 marine species.
- Coral reefs face threats such as pollution, climate change, overfishing, and invasive species; from 2009 to 2018, the world lost 14% of its corals.
Coral reefs are very diverse ecosystems that provide many types of marine life with food, shelter, and other needs. Almost 25% of marine life depends on coral reefs. Fishes, corals, crustaceans, invertebrates, and many more animals live in coral reefs.
Have you ever wondered what kind of coral reef animals live in these super unique ecosystems? We’re going to take a look at what coral reefs are and what type of animals live in these incredible ecosystems.
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What is a Coral Reef?
Coral reefs are formed by large colonies of individual coral polyps. The exoskeletons that these small coral reef animals leave behind create the corals we see in reefs.
Coral reefs develop in subtropical and tropical waters. These ecosystems usually develop in warm shallow waters because some species that help build them need sunlight.
The ideal water temperature for coral reef development is about 75°F (24°C). If ocean temperatures get too high, it can be harmful to a reef.
According to the United Nations Environment Programme, coral reefs can be found in more than 100 countries and territories.
One of the most notable coral reefs is the Great Barrier Reef found off the coast of northeast Australia. Located in the Coral Sea, the Great Barrier Reef is the largest coral reef in the entire world. It covers about 133,000 square miles (344,468 sq km) of the sea.
The Great Barrier Reef is home to at least 9,000 marine species. It’s made up of more than 2,000 individual coral reef systems and hundreds of coral species.
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Types of Coral Reef Animals
Millions of marine species depend on coral reefs at some point throughout their lifespan.
Coral reefs provide many benefits to marine animals, such as food sources, breeding grounds, and habitat.
If we compiled a list of all the marine animals known to live in coral reefs, it’d seem like this list would go on forever! Instead, we’ve chosen some common and unique coral reef animals to explore.
Coral is the heart of coral reefs. Despite looking like sea plants, corals are actually animals. Individual coral polyps live in large, close-knit colonies that create coral reefs. Individual coral polyps are very small and soft.
Coral polyps form a hard exoskeleton made of calcium carbonate on the outside of their bodies. This hard exoskeleton is what we see when looking at hard, stony corals. The exoskeletons continue to pile up as coral polyps create them.
The exoskeletons remain even after the coral polyp dies. It takes coral polyp colonies hundreds to thousands of years to build up.
A special algae called zooxanthellae gives corals its vibrant colors. Zooxanthellae goes through photosynthesis, which benefits coral polyps by providing nutrients and oxygen.
The algae and coral polyps have a mutualistic relationship. Coral polyps provide zooxanthellae with carbon dioxide. Zooxanthellae can turn coral into various colors of green, brown, and red. Coral itself can be transparent or purple, blue, or mauve.
2. Day Octopus
The day octopus inhabits coral reefs in the Indo-Pacific region. Its range extends from the east coast of Africa to Hawaii. These medium-large cephalopods are closely related to squids and cuttlefish.
Most octopuses are active at night, which is when they hunt for food. As their name suggests, day octopuses lurk around coral reefs during the day in search of food.
Like most octopuses, the day octopus has the ability to change color and texture to hide from predators. These camouflage experts can take on a variety of shapes and colors to imitate objects or blend into their background.
3. Red-banded Coral Shrimp
The red-banded coral shrimp is widely distributed in many different oceans. It can be found in coral reef habitats in tropical waters. It lives in fairly shallow waters, ranging from 2-210 meters (6.6-689 feet) in depth.
This shrimp is named for its intricately patterned color of red and white bands on its body. Red-banded coral shrimp help keep a coral reef healthy because of their diet.
They feed on parasites and injured tissue. They also clean food particles off of coral reef fishes, such as morays and groupers. They have a mutualistic relationship with the fish they clean.
4. Zebra Moray
The zebra moray is a type of eel named for its zebra-like stripes along its body. Zebra morays inhabit holes and crevices in coral reefs.
They hide during the day and venture out at night to hunt for food. They mainly feed on crustaceans, mollusks, and sea urchins.
Zebra morays are native to coral reefs in the Red Sea, North Pacific Ocean, and Caribbean Sea. Zebra morays differ from other moray eels because they don’t have pointed teeth. Instead, their teeth are more flat. This allows them to easily munch on their hard-shelled prey.
5. Pygmy Seahorse
Pygmy seahorses live amongst gorgonian corals in the Indo-West Pacific Ocean. They have a very unique look.
Some individuals have intricate dark markings all over their body over a light pink to white background color. Others can be light pink, cream, orange, or red. They have vibrant round knob-like bulbs called tubercles on their body.
Pygmy seahorses are very small. Individuals can range from 0.5-1.06 inches (1.3-2.7 cm) in length.
The very first pygmy seahorse discovered was the bargibant’s pygmy seahorse in 1969. This species has the ability to change color based on the gorgonian coral it’s living in.
6. Spotfin Lionfish
The exotic spotfin lionfish is considered an invasive species in many coral reef systems. It’s native to the Indo-Pacific region. They’ve managed to find their way in the western North Atlantic and Caribbean, where it’s considered invasive.
The spotfin lionfish is named for its striking pattern of vertical bands along its body. It has pointy spines that stick out around the body, which contain venom. Spotfin lionfish are often kept in aquariums as an exotic pet.
Despite being out-sized by many other coral reef animals, the spotfin lionfish is considered a top predator in the ecosystem.
The green sea turtle is a widely distributed species found in a variety of subtropical and temperate bodies of water around the world.
It’s considered endangered in the central South and West Pacific. It’s listed as a threatened species under the Endangered Species Act (ESA) throughout most of its range.
Green sea turtles get their name from their green skin. These sea turtles snack on a lot of seagrass and algae, which gives them their green color.
Green sea turtles are large marine reptiles that can reach up to 350 pounds! Thanks to these sea turtles, seagrass beds stay trimmed and healthy.
8. Crown-of-Thorns Starfish
Crown-of-thorns starfish are invertebrates that live in coral reefs, where they snack on their favorite food. These starfish love to eat coral as adults.
Due to their diet and explosive population growth, crown-of-thorn starfish are becoming harmful to coral reefs. They’re becoming a huge problem for the Great Barrier Reef.
These giant starfish can have more than 20 arms. They’re named for the spiky thorns they possess all over their body, which have a toxin in them.
There are at least four crown-of-thorn starfish species identified, which live in different bodies of water. Two species live in the North and South Indian Ocean, while the others live in the Red Sea and Pacific.
Giant triton snails and starry pufferfish aren’t deterred by the toxic spikes and are predators to the species.
9. Sea Urchins
Sea urchins are spiky, round invertebrates. Many sea urchin species are beneficial to coral reef systems. They eat a variety of things, including harmful algae that can build up on coral. An abundance of harmful algae can overwhelm coral. Sea urchins help keep it at bay.
A study on the long-spined sea urchin stated that in early 2022, the population suffered a drastic 98% decline in Florida and Caribbean waters. This rapid decline can have a negative impact on the already struggling corals in the region.
Sea urchins were originally thought to have a lifespan of about 7-10 years. However, some species may live more than 100 years!
10. Sea Sponges
Contributing to the vibrancy of coral reefs are sea sponges. Some may be more colorful than others, but these porous coral reef animals can range from bright yellow and orange to red and violet.
Sea sponges help keep coral reef systems healthy by acting as natural water filters. Their porous bodies can suck in water and filter bacteria from food particles. They’ve been around for hundreds of millions of years. There are more than 8,000 sea sponge species recognized.
Sea sponges and corals have some similarities in the way they resemble plants, but are actually marine animals.
11. Caribbean Spiny Lobster
Caribbean spiny lobsters are named for the pointy spikes they possess on their body. Along with their hard shell, the spikes help protect them from predators.
These lobsters can be found in the western Atlantic, Gulf of Mexico, and the Caribbean Sea. They live in a variety of habitats, including coral reefs, coastal waters, mangroves, and the open ocean.
They hide in holes or crevices during the day and hunt for food at night. Juveniles will eat smaller prey and plant matter. Adults are mainly carnivorous, feeding on various sea snails, clams, and crustaceans.
Caribbean spiny lobsters are threatened by overfishing because their meat is highly sought after.
12. Queen Conch
Queen conches are herbivores that feed on various plant matter, such as algae. Their range extends from the subtropical waters of the Florida Keys to the Gulf of Mexico, the Caribbean Sea, and Bermuda.
Queen conches mostly live in seagrass beds or algal flats, but they’re also associated with coral reefs.
Queen conches are highly valuable in the Caribbean and harvested for their meat. In September 2022, the National Oceanic and Atmospheric Administration submitted a proposal to encourage the queen conch to be listed as a threatened species under the ESA.
13. Bluespotted Stingray
The bluespotted stingray is easily recognizable by its beautiful blue spots scattered across its body. These stingrays can easily be confused with the bluespotted ribbontail ray, which has more blue spots and a rounder body.
Bluespotted stingrays live in coral reefs in the Indo-West Pacific region. They’re common along the northern coast of Australia and found in the Great Barrier Reef. They help other coral reef fishes by ridding them of parasites.
These stingrays typically travel into shallow waters in large groups to feed. Their favorite food is mollusks, but they also eat crustaceans. They retreat to deeper waters during low tide.
14. Regal Blue Tang
The regal blue tang is a tropical fish found in the Great Barrier Reef and the Indo-West Pacific.
These fish are commonly seen in pet stores and aquariums. You may also recognize it from the movies Finding Nemo and Finding Dory.
Regal blue tangs are often mistaken for blue tangs, which are only found in the coral reefs of the Caribbean Sea. Blue tang adults are almost completely blue. Juveniles are yellow. Regal blue tangs are royal blue and black with yellow fins.
The spiny fins on the top of this fish are venomous. They mainly eat zooplankton.
15. Reef Stonefish
The reef stonefish is a species of stonefish belonging to the subfamily Synanceiinae.
These fish belong to the family Scorpaenidae, which includes several venomous fish species. The reef stonefish is considered highly venomous.
It’s named for its unique look, which resembles stone that allows them to blend in with rocks or stony corals. They often remain hidden around coral or rocks waiting to capture prey. Their diet mainly consists of various coral reef fishes and invertebrates.
Reef stonefish are native to the Indo-Pacific. They can be found in the Great Barrier Reef and other coral reef systems in the Red Sea and East Africa.
16. Yellow-headed Jawfish
Yellow-headed jawfish are small iridescent fish that live in the coral reefs of the western Atlantic and Caribbean Sea. Their habitat is located along coral reef edges where there’s little protection.
To hide from predators, they create burrows in the sand. They’re named for their yellow head and wide mouth. Yellow-headed jawfish use their wide mouth to scoop up sand and rocks to dig their burrows.
These fish live in large colonies of 50 individuals or more. Their burrows can be up to 12 inches (30.5 cm) deep. They mainly feed on zooplankton and small reef fishes.
17. Leafy Sea Dragons
The leafy sea dragon is a very unique-looking species closely related to pipefish and seahorses. They’re named for their appearance, as they have fins that look like leaves hanging from their body. The shape of their body looks like a dragon.
Leafy sea dragons have a long-snout, similar to a seahorse. They reach about 14 inches (35 cm) in length.
Their appearance helps them blend in with sea plant matter, such as seaweed. Leafy sea dragons live in coastal waters in rocky reef habitats found around Western and South Australia.
Leafy sea dragons love to eat mysid shrimp. They’re constantly eating because they don’t have a stomach.
18. Marine Angelfish
Marine angelfish are tropical fishes that live in the coral reefs of the Atlantic and Indo-West Pacific. There are several different species that belong to the family Pomacanthidae. Many individuals are brightly colored, with bold stripes or spots all over.
Angelfish are very popular in the aquarium trade and usually seen in pet stores. Their diet widely varies between species. Some individuals feed on zooplankton, while others feed on algae, invertebrates, or sea sponges.
Species that have bright, electric colors can help deter predators, as it fools them into thinking these fish are toxic.
Clownfish are common aquarium fish found in the Indo-Pacific region. They live in coastal and outer reefs and lagoons. Clownfish are easily recognizable by their bright orange background color and prominent white stripes.
Clownfish have a mutualistic relationship with the stinging sea anemones they live in. The sea anemones provide clownfish with shelter and protection from other fish who get stung by the anemone’s nematocyst stinging cells.
As clownfish feed, they provide their host anemones with food from leftover particles.
Clownfish are covered in a layer of mucus, which the nematocysts of stinging sea anemones don’t recognize as food. This is why clownfish can live amongst these sea anemones without getting stung.
20. Gray Reef Shark
The gray reef shark is one of many reef shark species that depend on coral reefs for food. They live along the coasts of islands and continents in the Indo-Pacific and West Pacific Oceans.
Grey reef sharks are found in subtropical and tropical waters in habitats near coral reefs and coral atolls. They visit coral reefs to feed on various reef fishes, crustaceans, and cephalopods.
Grey reef sharks are considered aggressive and pose a threat to humans. However, their aggression is mostly triggered by feeling threatened.
According to the International Shark Attack File, grey reef sharks are responsible for 8 confirmed non-fatal unprovoked attacks in modern history.
21. Caribbean Reef Shark
Caribbean reef sharks are native to the Caribbean Sea and surrounding tropical bodies of water. Their range extends from the Atlantic coast of South Florida, the Gulf of Mexico and Caribbean Sea south to the eastern coast of South America.
Caribbean reef sharks are one of the most common sharks roaming the Caribbean waters. They live around coral reefs in the region. They feed on bony coral reef fishes.
Although they’re a common inshore species, there are very few confirmed Caribbean reef shark attacks on record.
They’re medium-large sharks that can reach up to 9 ft (2.7 m) in length. Although not considered highly aggressive, their size should be respected.
22. Broad-barred Goby
The broad-barred goby fish is found in the Indo-West Pacific region, including the Great Barrier Reef. There are many different types of saltwater goby fish that live in coral reef habitats.
Broad-barred goby fish are usually light green with intricate red to red-orange stripes and squiggles on the top half of the body and head. These fish help coral reefs by eating harmful seaweeds that can overwhelm the corals.
Researchers discovered that corals have the ability to send goby fish chemical signals to let them know they need help. Some goby species will eat away at the harmful seaweed, while others species trim it down without consuming it.
Some reef gobies will eat mucus and algae build-up on corals. This symbiotic relationship allows corals to stay healthy and in return, provides gobies with shelter or food.
23. Bearded Fireworm
The bearded fireworm looks like a large, fuzzy sea caterpillar. They belong to the family Amphinomidae, which includes bristle worm species.
Bearded fireworms are fairly large, reaching up to 14 inches (35.6 cm) in length. The bristles that cover bearded fireworms contain venom.
These sea worms can be found in coral reefs in the western Atlantic and around Ascension Island. Bearded fireworms can be harmful to corals because they feed on them. They also eat crustaceans and sea anemones.
24. Flamboyant Cuttlefish
There are several types of cuttlefish that live in coral reefs. The flamboyant cuttlefish is found in coral reefs in the Indo-Pacific region, including the Great Barrier Reef. Cuttlefish belong to the cephalopod group. They’re closely related to octopuses and squids.
Like many cephalopod species, cuttlefish have special characteristics that give them color-changing abilities.
According to Museum Victoria marine biologist Mark Norman, flamboyant cuttlefish are highly toxic. The flamboyant cuttlefish is the only cuttlefish species known to have highly toxic venom.
These cephalopods are most active during the day. They feed on various small reef fishes and crustaceans.
Parrotfish are brightly-colored tropical fish that live in coral reefs around the world. There are more than 70 parrotfish species.
Parrotfish can be both harmful and helpful to coral reefs. Some species eat algae off of coral. Parrotfish also like to snack on the exoskeletons of hard corals, coral polyps, and even zooxanthellae.
These fish have a hard beak in the form of teeth that allows them to munch on hard corals. Although they feed on coral, their diet of algae on coral is essential to keep coral reef systems healthy.
Types of Coral Reefs
There are different types of coral reefs found around the world. Coral reefs are mainly distinguished by how they form and where they’re located. There are three main types of coral reefs recognized, which include:
- Fringing reefs
- Barrier reefs
- Coral atolls
Fringing coral reefs surround land masses and develop directly from shorelines out to sea.
Fringing coral reefs are the most common type of coral reef in the world. Reef systems found in Hawaii and most of the Caribbean are examples of fringing reefs.
Barrier reefs form similarly to fringing coral reefs. The main difference is barrier reefs have a deep body of water that separates the reef from shorelines. These coral reef systems are common in the Indo-Pacific region and the Caribbean Sea.
Coral atolls are unique because they form as a result of the gradual sinking of volcanic islands over millions of years. The coral reefs slowly develop around a volcanic island. The coral reef remains as the volcanic island sinks over time.
A coral atoll forms when the volcanic island is completely submerged and leaves a lagoon in the center.
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Threats to Coral Reefs
Coral reefs face many threats as a result of natural and human activity. According to the Global Coral Reef Monitoring Network’s 2020 coral reef status report, the world has lost 14% of its corals from 2009-2018.
Some of the main threats to coral reef systems include:
- Climate change
- Invasive species
Pollution and climate change threats are largely fueled by human activities. Coral reefs are fragile ecosystems that need special environmental conditions to develop. Since it takes coral reefs a long time to develop, they can be wiped out before they have time to recover.
Climate change can lead to rising sea levels and warming ocean temperatures. Coral reefs are vulnerable to coral bleaching. This phenomenon occurs when coral turns white as a result of higher than normal water temperatures.
There are many different types of pollutants that can harm coral reefs. Pollution can come in the form of sedimentation, runoff, and marine plastic and other trash. This can not only harm corals, but also the coral reef animals living in the ecosystem.
Invasive species introduced to coral reefs can destroy coral. Coral reef animals are also threatened by invasive species.
Coral Reef Animals FAQ
What is the most common animal in coral reefs?
Corals are the most common animals found in coral reefs. These plant-like animals are what make up entire coral reef systems. Individual coral reef polyps are responsible for building the hard exoskeletons that cover the actual corals.
There are thousands of types of coral found in coral reefs. The two main categories include hard coral and soft-bodied coral. Many hard corals are a type of stony coral.
Why is coral reef important to animals?
Coral reefs are very productive ecosystems that provide a wide variety of marine life with habitat, protection, food, and breeding grounds. Many coral reef animals have positive symbiotic relationships with coral and other coral reef creatures.
Other marine animals that don’t live in coral reefs can also benefit from the diverse ecosystem. For example, sharks don’t live in coral reefs but they visit them in search of food. Marine life and humans would suffer if all the coral reefs died out.
How many coral reefs are there left in the world?
Coral reefs make up less than 0.5% of the entire ocean floor. According to the World Resources Institute, Australia accounts for 16-20% of the world’s coral reef coverage. Australia is also home to the largest coral reef, the Great Barrier Reef.
Indonesia also has extensive coral reef systems. The exact number of coral reefs in the entire world is unknown. But based on World Population Review data, there’s more than 100.
What animal looks like a coral reef?
There are many species that have features that resemble objects and animals found in coral reefs.
The leafy sea dragon can easily blend in with seaweed with their leafy-like fins. The reef stonefish is a master of disguise because it looks like a stone sitting still on the seafloor.
Octopuses have the ability to blend in with their surroundings and imitate the appearance of objects. They have special color-changing abilities to match their background. They can also change their texture to blend in with their environment.