© Background image: Tracey Jennings
Here, each species – from the iconic thresher sharks to the endangered green sea turtles, and the rare, endemic Banggai cardinalfish—plays a vital role in maintaining the ecological balance and health of their habitats. Unfortunately, many of these marine creatures face significant threats such as overfishing, habitat destruction, and the broader impacts of climate change. Recognising the interconnectedness of marine life and the benefits of intact marine ecosystems is crucial. We showcase the critical roles of a wide array of marine species in our Marine Protected Areas and beyond, the pressures they face, and the conservation efforts needed to protect these species and ensure the resilience and recovery of coral reefs worldwide.
These species fulfill essential functions in sustaining the balance and health of their ecosystems. Whether they are serving as important predators or prey, or enhancing the structural integrity or functionality of the habitat, their contributions are vital for the resilience and productivity of the ecosystem.
Iconic species, well-known or holding symbolic value, captivate public interest and boost awareness about marine conservation. They often act as powerful ambassadors for their environments.
These species are at a significant risk of disappearing from the wild soon due to threats such as habitat destruction, pollution, climate change, overfishing, and the illegal wildlife trade. Protecting these species and their environments is essential to prevent their extinction and preserve biodiversity.
The IUCN Red List is a system used to classify the conservation status and extinction risk of species. It is recognised as the most authoritative guide to the status of biological diversity. The list is divided into nine categories, each indicating the level of extinction risk faced by different species.
The IUCN Red List is crucial for identifying species needing targeted recovery efforts and focusing the conservation agenda.
The Banggai cardinalfish is one of the rarest and most striking fish found in Indonesia’s Banggai Archipelago. Characterised by a silver body with black stripes and white spots, this small fish has become iconic among aquarium enthusiasts. Its popularity has led to overexploitation, and its restricted range makes it particularly vulnerable to extinction. Conservation efforts – including more sustainable aquarium trade practices and habitat protection – are imperative to ensure the survival of this species.
Parrotfish play a pivotal role in coral reef ecosystems, where they feed on algae, coral, and other invertebrates. Using their beak-like teeth, they scrape the algae off the coral, and in the process, they end up eating some coral as well, which they grind and digest. They then excrete the undigested coral as sand, which helps to create and maintain sandy beaches. By grazing on algae that compete with coral, they promote reef health and regeneration. However, parrotfish face threats from overfishing and habitat destruction, which in turn threatens the resilience and recovery of coral reefs around the world.
Green sea turtles are the second largest sea turtle species, with their name being derived from the greenish colour of their cartilage and fat. This is due to their diet consisting predominantly of seagrasses – in fact, they are the only herbivorous species of sea turtle. They are known to migrate over vast distances, and are vital to the diversity and productivity of marine ecosystems due to their contribution to the health of seagrass beds and coral reefs. Throughout their global range, they face threats from poaching, habitat loss, and climate change, and are often caught as bycatch in fisheries operations.
Hawksbill sea turtles, with their distinctive hawk-like beaks and beautifully patterned shells, are found on tropical reefs worldwide. They help to maintain the health of coral reefs by controlling sponge populations. However, this ancient marine species faces severe threats from the illegal wildlife trade and accidental capture in fishing nets. Habitat loss from coastal development and climate change also endangers them by reducing nesting sites and killing coral reefs they rely on for food. International cooperation is crucial for the conservation of hawksbill turtles. Advocates work to establish marine sanctuaries, while researchers collect data to raise local awareness and improve conservation strategies.
The Napoleon or humphead wrasse is a regal presence on coral reefs thanks to its striking appearance and imposing size. Found throughout the Indo-Pacific region, from the Red Sea to the central Pacific, this species preys on invertebrates that could otherwise harm coral formations. Their ability to eat toxic species such as crown-of-thorns starfish speaks to their ecological importance. Due to overfishing and habitat destruction, their numbers are declining – highlighting the need for international, collaborative conservation efforts.
Green humphead parrotfish act as coral reef architects – by consuming dead coral and excreting it as sand, they contribute to the creation of sandy beaches and the dispersal of coral larvae, thereby aiding in reef regeneration. Their large size and unique appearance make them an iconic species within our Marine Protected Areas and beyond. However, due to overfishing and habitat loss, their numbers are dwindling.
Thresher sharks, with their elongated tails that can be as long as the shark’s body itself, are one of the ocean’s most mesmerising species. They use their impressive tails to stun prey, making them effective and efficient hunters. However, they are increasingly vulnerable to threats, including bycatch and targeted fishing for their valuable fins. The loss of thresher sharks could disrupt marine food chains, leading to unforeseen consequences for ocean ecosystems. Protecting them is not only a question of conserving a unique species, but also of maintaining the balance and health of marine environments.
The scalloped hammerhead shark, with its distinctive head (the shape of which is believed to enhance its sensory capabilities) is found in warm waters around the world. Highly migratory, the scalloped hammerhead travels long distances to feed and breed. It is a social species, forming large schools of up to hundreds of individuals. As apex predators, they help maintain the balance of marine life; however, their populations are in decline due to overfishing, particularly for the shark fin trade, and habitat degradation.
The great hammerhead shark is one of the ocean’s most distinctive and misunderstood creatures. With its immediately recognisable head and imposing size, it has a greatly exaggerated reputation for aggression towards humans. These solitary and nomadic tropical water predators play a vital role in controlling prey populations, thereby contributing to the health of marine ecosystems. Great hammerheads are increasingly vulnerable due to overfishing and the shark fin trade.
Blacktip reef sharks, with their distinctive, black-tipped fins, play a vital role in coral reef ecosystems. They keep fish populations healthy by preying on weak and sick individuals, thus preventing the spread of disease and ensuring species diversity. Their relatively small size and curious nature make them a favourite among snorkelers and divers. These sharks face threats from habitat destruction and the fin trade. Efforts to protect their habitats and regulate fishing practices are crucial for their survival and the overall health of reef ecosystems.
Whitetip reef sharks are known for their nocturnal hunting habits which play a key role in controlling the population of nocturnal prey species and ensuring a balanced ecosystem. Unlike other requiem sharks, they can pump water over their gills and lie still on the seafloor. Their slender bodies allow them to navigate through tight spaces in the reef as they hunt for food. However, the decline in their populations due to fishing pressures and habitat loss is alarming.
Grey reef sharks are crucial for the health of coral reefs, acting as apex predators and maintaining the balance of marine life. Despite their modest size, they often dominate over other shark species. Their sleek, powerful form is a common sight in tropical ocean waters, and their presence is a sign of a healthy, thriving ecosystem. Unfortunately, their populations are declining due to overfishing, bycatch, and the degradation of coral reef habitats.
The walking shark, or Raja Ampat epaulette shark, represents one of nature’s most fascinating adaptations. Found primarily in the waters of Indonesia, particularly around the Raja Ampat Islands, this species uses its fins to ‘walk’ along the ocean floor rather than swimming. This unique mode of locomotion allows it to hunt for small fish and invertebrates among coral reefs and tide pools. Found primarily in coastal waters, they prey on small crustaceans and control the populations of other organisms. Habitat degradation due to pollution, coastal development, and unsustainable fishing practices pose severe threats to walking sharks, while their slow rates of reproduction limit their ability to recover from population declines. The aquarium trade further threatens these sharks, making conservation measures, including marine protected areas (MPAs) and sustainable fishing practices, crucial to safeguarding the future of this species.
The pearl bubble coral is a unique species, distinguished by its pearl-like vesicles that inflate during the day to capture sunlight for its symbiotic algae, and retract at night to reveal its feeding tentacles. This fascinating behaviour not only showcases the coral’s adaptability but also its critical role in the nutrient cycles of coral reef ecosystems. The pearl bubble coral provides shelter and nourishment to a variety of marine organisms, contributing to the complex web of life that defines coral reefs. However, it is vulnerable to the effects of climate change, such as coral bleaching, as well as pollution and physical disturbance from human activities.
Galaxea spp. are known for their long, sweeping tentacles and dense clusters of star-like polyps. These hard corals plays a significant role in reef-building, contributing to the structural integrity of coral reefs which provide essential habitats for a diverse range of marine life. They thrive in clear, saltwater environments and are generally found at depths around 15 meters, although they can range from 1 to 30 meters deep. Like many coral species, Galaxea spp. face threats from land-based pollution, unsustainable fishing practices, temperature fluctuations leading to coral bleaching, ocean acidification, and physical damage from human activities. Protecting these corals requires climate change mitigation and the implementation of effective marine conservation strategies.
Acroporids, with their intricate branches, are the most diverse shallow-water genus. There are at least 150 recognised species. Acroporids are foundational species of tropical reefs found in the Indo-Pacific, Caribbean, and Red Sea regions, creating complex habitats that support a vast array of marine life. These corals are cornerstones of biodiversity, providing shelter and nursery grounds for numerous fish and invertebrate species. However, they are among the most vulnerable to threats such as coral bleaching, ocean acidification, and physical damage. The preservation of acroporid corals is crucial for the resilience of reef ecosystems and the protection of the marine diversity they support.
Groupers are a diverse family of fish known for their robust size and significant role within marine ecosystems globally, from the Caribbean to the Indo-Pacific. As predators, they help maintain the balance of marine life by controlling populations of smaller fish. However, their slow growth rate and late maturity make them vulnerable to overfishing. More sustainable fishing practices are needed to ensure healthy population sizes and the ecological equilibrium of their habitats.
The giant trevally, a formidable predator known for its strength and size, uses novel hunting strategies, such as shadowing monk seals, using sharks to ambush prey, and leaping out of the water. Renowned for its explosive bursts of speed in pursuit of prey, the giant trevally plays a crucial role in maintaining the balance of marine ecosystems, regulating the populations of prey species and contributing to ecological stability.
Sweetlips are known for their large, fleshy mouths and distinctive colour patterns that can change throughout their development. Belonging to the grunt family of fishes, they make a significant contribution to coral reef biodiversity and ecological balance by preying on smaller marine organisms. They feed mostly at night, and their diet is typically made up of crustaceans, molluscs, and worms. However, they are vulnerable to overfishing, and depend on healthy coral reefs for survival.
The brindled grouper, also known as the giant grouper, is the largest bony fish found on coral reefs and displays striking camouflage patterns. Found in Indo-Pacific waters, it plays a pivotal role in reef ecosystems as a predator, preventing overgrazing of the reef by other fish species. The brindled grouper faces threats from overfishing, habitat destruction, and pollution.
Coral groupers, with their striking patterns and colours, are prized inhabitants of coral reefs across the Indo-Pacific region. As predators, they play a vital role in maintaining the health and diversity of reef ecosystems by controlling populations of smaller fish. However, their beauty and highly valued meat have led to overfishing, placing many species at risk.
Manta rays, with their graceful movements and impressive wingspans, are among the ocean’s most compelling inhabitants. Found in tropical, subtropical, and temperate waters around the world, they are an important strand in the food web of the ocean, as they are filter feeders that help remove excess organic matter and bacteria. They are also much sought-after by divers and snorkelers. Despite their ecological importance and popularity among ecotourists, they are threatened by targeted fishing, bycatch, and habitat loss.
The Indian Ocean humpback dolphin, characterised by its distinctive hump, frequents the shallow coastal waters of the Indian Ocean from South Africa to India, including the waters around Zanzibar. It is one of the most endangered dolphins in the world, facing threats from habitat loss, fishing gear entanglement, pollution, and hunting, making its status precarious.
Octopuses are masterful escape artists, known for their intelligence, ability to change colour, shape, and texture, and remarkable problem-solving skills. Inhabiting diverse marine environments globally, from shallow reefs to the deep sea, they play a key role in the food web as both predators and prey. Due to their capacity for adaptation and their enigmatic nature, octopuses have long captivated scientists and divers alike.
The sperm whale, the largest of the toothed whales, is revered by many cultures for its intelligence, sociability, and exceptional diving abilities. Capable of reaching great depths in search of giant squid, fish, and other prey, sperm whales play a significant role in marine ecosystems by influencing the vertical distribution of nutrients between different ocean layers. Found in all deep oceans, from the Equator to the Arctic and Antarctic Oceans, sperm whales face threats from whaling, ship strikes, entanglement in fishing gear, and pollution.
The longheaded eagle ray, with its distinctive elongated snout and graceful flight-like movements, is a captivating sight in the coastal waters of the Indo-Pacific region. It plays a crucial role in the health of marine ecosystems, helping to control populations of bottom-dwelling invertebrates. It is an iconic species, as it is one of the most elegant rays, and is much sought-after by divers and snorkelers. Unfortunately, it is also threatened by habitat loss, bycatch, and targeted fishing.
Jacks, with their streamlined bodies and swift swimming abilities, are vital components of tropical and subtropical marine and estuarine ecosystems around the world. Their presence is indicative of healthy, vibrant ecosystems. However, like many marine species, jacks face pressures from overfishing and habitat degradation, highlighting the need for sustainable management of marine resources to ensure the sustainability of ocean ecosystems.
The potato grouper is a majestic and solitary hunter, often found lurking in the depths of coral reefs and rocky outcrops. As an apex predator, it plays a critical role in maintaining the balance of marine ecosystems by regulating the populations of smaller fish. Unfortunately, its size and the quality of its meat make it a target for spearfishers and commercial fisheries, leading to a significant decline in its population in many parts of its range.
Snappers, a group of reef and pelagic fish, are both economically and ecologically important. They play a significant role in maintaining the balance of marine ecosystems and are vital for commercial and subsistence fisheries. However, they face pressure from overfishing and habitat loss. Sustainable management and conservation of snapper populations are critical for maintaining the health of marine ecosystems and ensuring food security.
Moorish idols are known for their eye-catching black, white, and yellow bands and elongated dorsal fin. They have a unique, disc-shaped body, a tubular snout, and small bony protrusions above their eyes. They are a popular species among both divers and aquarium enthusiasts, and are considered a symbol of happiness and fidelity in some cultures. Their presence on coral reefs is a reliable barometer of ecosystem health, and their conservation is vital for the biodiversity and resilience of coral communities because they help control algae and serve as a food source for reef predators.
Despite their diminutive size, blue-ringed octopuses are among the most venomous of all marine creatures. They are found in tidal pools and on coral reefs throughout the Pacific and Indian Oceans, down to depths of around 50m. Bue-ringed octopuses spend most of their time hiding in crevices, relying on their effective camouflage and piling up rocks outside their lairs to safeguard themselves from predators. If provoked, they rapidly change colour, becoming bright yellow with iridescent blue rings – a warning that it pays to take note of. The bite of these octopuses carries a potent neurotoxin which causes paralysis, and can be fatal to humans. Mouth to mouth resuscitation can be effective in the event of a bite.
Sea anemones are the jewels of the ocean floor; their vibrant colours and flowing tentacles creating mesmerising displays in reef environments. These animals have stinging cells, which they use to capture and paralyse prey such as fish, crustaceans, and worms. However, they also serve as protective habitats for a variety of marine species, including the iconic clownfish, which is immune to the stings and uses the anemone as a shelter and a food source. Found in oceans worldwide, sea anemones contribute to the structural complexity and ecological richness of marine habitats.
The ethereal ghost pipefish are usually found in seagrass beds, coral reefs, or on sandy seafloors, where they excel in mimicking their surroundings. These close relatives of seahorses blend in seamlessly – a survival strategy that fascinates divers and marine biologists alike and contributes to their resilience to threats.
Disco clams illuminate the ocean floor with their unique flashing light displays. Also known as electric flame scallops, the edges of these small marine bivalves flicker like a disco ball, a phenomenon caused not by bioluminescence but rather by reflective tissue on the edge of their mantle, which they can move rapidly to create a strobe-like effect. They use these lights to communicate, attract mates, and deter predators. Disco clams are important for their role in nutrient cycling and enhancing the water quality of coral reefs. They assist in removing excess organic matter and bacteria, and contribute to the reef’s integrity and ability to support a wide variety of marine life.
Dugongs are herbivorous marine mammals, and can grow up to 3 metres in length. They play a crucial role in maintaining healthy seagrass beds – vital habitats that support diverse marine life and act as carbon sinks. Facing threats from habitat degradation, entanglement in fishing gear, collisions with boats, and hunting, the decline in dugong numbers highlights the need for concerted conservation efforts to protect these gentle marine mammals and the critical habitats they depend on.
There are approximately 40 species of triggerfish, and they are known for their bold colours, distinctive shapes, and role as reef architects. Found across tropical and subtropical waters, these resourceful fish contribute to the balance of reef ecosystems by controlling populations of sea urchins that would otherwise degrade reef structures. Triggerfish move rocks and debris as they create nesting sites; consequently, they play an important role in the ecosystem’s sediment dynamics.
Mantis shrimps are known for their vibrant colours and extraordinary hunting abilities, including their lightning-fast strikes. Inhabiting tropical and subtropical waters, these creatures play a vital role in the marine food chain. Mantis shrimp also have the most complex eyes in the animal kingdom, with 12 to 16 types of photoreceptors, compared to humans’ three. They can see ultraviolet and polarised light, and they have trinocular vision, meaning they can perceive depth with each eye. They also have independent eye movements, which allow them to scan their surroundings with high accuracy. Their unique behaviours and complex eyesight challenge our understanding of the natural world, offering insights into the evolution of sensory perception.
Swordfishes are large, highly migratory predatory fish characterised by a long, flat, pointed bill. They inhabit the tropical and temperate regions of the Atlantic, Pacific, and Indian Oceans. Swordfish are known for their speed and agility, and they rely also on their exceptional vision to capture the fish and squid they feed on. They prefer ocean temperatures between 18-22°C. However, swordfish larvae are often found in waters warmer than 24°C. Interestingly, they possess a specialised tissue behind their eyes that produces its own heat, protecting their eyes and brain from rapid temperature changes. Swordfish face threats from overfishing, habitat destruction, and climate change.
These members of the anglerfish family are experts in mimicry and are usually found on or near the bottom in tropical and subtropical waters. Their ability to camouflage themselves as coral or rocks makes them formidable ambush predators. Frogfish have a modified dorsal fin that acts as a lure to attract prey. They also have a large mouth that can swallow their prey whole. These creatures exemplify the incredible adaptations marine species have adopted to survive.
The vibrant communities of fusiliers, butterflyfish, and damselfish are a draw for ecotourism and exemplify the dynamic life of coral reefs. Fusiliers dart through the water in shimmering schools, butterflyfish graze on coral polyps, and damselfish defend their algae farms with vigour. Each species plays a critical role in the reef’s ecology, from maintaining coral health to ensuring algae levels are kept in balance.
The false percula clownfish forms a symbiotic bond with anemones, a relationship that is crucial for their survival. These iconic fish with their vibrant orange and white markings are immune to the stinging cells of their hosts, and they use the anemones as a shelter and a food source. In turn, they protect the anemones from predators and parasites, and provide nutrients from their waste.
Gobies, one of the most diverse marine fish families, are usually found in shallow waters. These small, often brightly coloured fish, thrive in a variety of habitats, including coral reefs, seagrass beds, mangroves, and estuaries. By cycling nutrients, providing food for predators, and engaging in fascinating symbiotic relationships with other species, they play a significant ecological role.
Known for their ability to inflate into a ball when threatened, puffer fish are a diverse group of species that play a significant role in marine ecosystems. Puffer fish play a vital role in marine ecosystems by preying on harmful invertebrates and controlling algae growth. However, their populations are at risk due to habitat loss, pollution, and overfishing – they are considered a delicacy in some cultures despite the presence of potentially lethal toxins in incorrectly prepared fish.
The pygmy seahorses comprise several species of tiny seahorses found in Southeast Asia within the Coral Triangle area. The Bargibant’s pygmy seahorse always lives on gorgonian corals (sea fans), spending its entire adult life on a single coral. Barely the size of a pencil eraser, its coloration, which can be pink, yellow, lavender, or brown, matches the coral it inhabits. Their existence hinges on the health of coral reefs, which are increasingly threatened by human activities and climate change.
Giant clams are the largest bivalve molluscs, with some specimens reaching over 1.3 metres in length and weighing over 200 kilograms. By harbouring symbiotic algae, they contribute significantly to the productivity of reef environments through the creation of a relationship that not only nourishes them but also assists in carbon fixing. Their magnificent size and the spectrum of colours they display make them iconic, and attracts divers and marine enthusiasts. However, giant clams face grave threats from overharvesting and the illegal trade in their shells and meat, alongside habitat destruction.
Azure damselfish, with their vibrant blue and gold hues, add an extra pop of colour to coral reefs. By feeding on algae, they prevent excessive growth that could otherwise smother corals. Despite their small size, azure damselfish are territorial and can be quite assertive. Unfortunately, this colourful species faces challenges from habitat degradation and climate change.
Surgeonfish are integral to coral reef health, thanks to their diet of algae, which if left unchecked, can smother corals and disrupt the delicate ecological balance. They are named for the unique scalpel-like spines on either side of their tail, which they use as a defence mechanism. With their vibrant colours and active nature, they are a favourite among divers and snorkelers. However, they are vulnerable to collection for the aquarium trade and habitat degradation.
The leaf sheep sea slug has an endearing resemblance to a cartoon sheep, and is one of the few creatures able to incorporate chloroplasts from the algae it eats into its own cells. This enables the leaf sheep to photosynthesise, and as a result, it is sometimes referred to as the “solar-powered sea slug”. Inhabiting the shallow waters of the Indo-Pacific, this tiny creature underscores the importance of preserving marine habitats, not only for their intrinsic value, but also for the role they play in broader ecological networks, where even the smallest components perform vital functions.
Barracudas, known for their fearsome appearance and lightning-fast speed, are iconic predators of tropical and subtropical waters. Their sleek, torpedo-shaped bodies enable them to dart through the water, ambushing prey with precision. Barracudas play a crucial role in maintaining the health of fish populations and the overall balance of marine ecosystems.
The Critically Endangered largetooth sawfish, distinguished by its long, toothed rostrum, inhabits tropical and subtropical waters, including coastal regions, rivers, and mangroves. It is an iconic and ancient species, and possesses cultural and spiritual significance for many people. It uses its saw-like snout to slash at and stun prey such as fish, crustaceans, and molluscs, but also to defend itself from predators, such as crocodiles and sharks. Once widespread, sawfish populations have declined dramatically due to habitat loss, bycatch, pollution, and overfishing, especially for their fins, which are used for shark fin soup. Conservation measures are vital not only for the species itself, but also for maintaining the health of the ecosystems these cartilaginous fish inhabit.
Blue marlin are among the largest and most sought-after fish in the ocean, known for their cobalt-blue colour and spear-shaped upper jaw. They can reach up to 4.2 meters in length and weigh more than 900 kilograms. Females live up to 27 years in the wild, and males up to 18 years. They are found in the tropical and temperate waters of the Atlantic, Pacific, and Indian Oceans. Blue marlin feed on mackerel and tuna, but will also dive deep to eat squid. As apex predators, they help regulate the populations of other species, which in turn maintains the health and stability of the oceanic food web.
The black marlin is one of the largest bony fish, reaching lengths of up to 4.65 metres and weighing as much as 700 kilograms, with a typical lifespan of 10 years. They are among the fastest fish in the ocean, reaching speeds of 22 mph. They feed mostly on fish, such as tuna, mackerel, and flying fish, as well as squid and octopus. Across their range, they face threats from overfishing (due to their coveted status as a sportfishing trophy) and habitat destruction.
Striped marlin are large, oceanic fish known for their bluish stripes and long, pointed bill. Found in tropical and subtropical regions of the Pacific and Indian Oceans, they feed on fish and cephalopods. They use their bill to slash through schools of fish, coordinating attacks in groups.
Also known as the yellow-lipped sea krait, these sea snakes are named for the striking black vertical bars on their white bodies. While spending much of their time in the waters around corals reefs of the eastern Indian Ocean and western Pacific oceans, these sea snakes come ashore to breed and lay their eggs. They have powerful venom which is used to paralyse prey (eels are a favourite food) which is then swallowed whole. These snakes appear to pose little threat to humans, and will usually bite only when provoked.
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