Island Escapes

Dangerous Animals of the Indian Ocean

Overview: The Western Indian Ocean

The western Indian Ocean includes some of the most beautiful destinations for dive tourism. It includes the coasts of central Somalia, Kenya, Tanzania, Mozambique and the central KwaZulu-Natal coast of South Africa. The islands of Pemba, Zanzibar, Mafia, Aldabra, Providence, the Seychelles, the Comores, Madagascar, Mauritius, La Reunion and Rodrigues are located within this region. These coastal nations and islands share biological and climatic features; it is a tropical area where the air temperature at sea level rarely falls below 20 degrees Celsius and seawater temperature is usually between 20 and 30 degrees Celsius.

Dive tourism has increased steeply here over the past few years. The attraction of the marine world has been brought into our homes via the media, and now that travel has become relatively easy and affordable, we want to discover the underwater world for ourselves. However, this world contains some dangers for the holiday-maker. In the following sections, some of the organisms that may be harmful are briefly described.

Some of the dangerous marine organisms described here are exclusively found in the western Indian Ocean region, while others are found in other areas of the Indo-Pacific and Pacific, as well.

Dos and Don’ts

WorldGuide continues its look at dangerous animals in the Indian Ocean with this list of ocean safety dos and don’ts.

Do get yourself a good marine identification guide

A good guide will help you familiarise yourself with the most-important marine organisms that you are likely to encounter. Not only will that make your dives more enjoyable, but it will also warn you about potentially harmful organisms. Richmond’s guide is an excellent, comprehensive guide and is highly recommended.
A Guide to the Seashores of Eastern Africa and the Western Indian Ocean Islands, SIDA. By Matthew D Richmond (1997).

Do pack a small medical kit

It is always a good idea to take along some disinfectant (alcohol), a diluted antiseptic solution (for example, a solution of 50 percent H2O2 [hydrogen peroxide] and 50 percent water), antihistamines, antibiotics, aspirin and a variety of plasters. A good sunblock is essential. On top of that I recommend that you start taking yeast capsules about a week before you leave and continue to take them daily. It will strengthen your gut flora and help you avoid getting diarrhoea.

Always obtain local advice regarding marine dangers before you enter the water. This advice might include which bays to avoid due to jellyfish, as well as information on dangerous tides, currents and sharks.

Wear rubber sandals or trainers when wading through shallow water. Shoes will protect your feet from being cut by coral or stung by marine organisms.

Don’t touch animals you don't know

This is the golden rule. It applies equally to both pretty shells and jellyfish washed up on the beach and organisms in the water.

Do not panic

Panicking is a common cause of accidents for divers, but it can also get you into serious trouble when you are swimming close to shore. If you run into difficulties, if you’re in pain, if you’ve been stung or bitten by a marine animal, try to keep calm. Similarly, try to calm down a victim of an accident.

Dangerous Animals in General

There are several distinct types of dangerous animals in the Indian Ocean. Marine animals compete for food and habitats and defend themselves from predators. They have developed a number of means to do so in the best way possible. Some are equipped with stinging cells, others with venomous spines, and the predators amongst them have developed strength and a good set of teeth. In the following sections, the most potentially dangerous groups of animals are briefly described, with suggestions on how to enjoy watching them without being hurt. It must be emphasised that it is quite possible that you will never encounter these animals on your dive trip, but if you’re lucky you may have the privilege. One of the most memorable experiences of any diver is to watch a shark quietly glide by. The beauty and elegance of this creature is awesome. If you simply observe, calmly, you will be enriched by your experiences.

The Stinging Kind

There is a variety of marine organisms in the Indian Ocean which can sting. The main groups to be aware of are the following: jellyfish and Portuguese men-of-war, rays, stone-, lion- and scorpionfish, cone shells.

The effect of a sting varies from one person to the next. Even relatively harmless jellyfish can cause an allergic reaction in some, whereas others just feel a slight temporary itch. There is some evidence that people who tend to develop allergies are more vulnerable, as are those who have been in contact with venomous marine creatures before and are consequently sensitised. But there are simple precautions that you can take to avoid being stung.


The sheer number of jellyfish in the world’s oceans is on the rise, a direct consequence of the overfishing of their natural predators which include tuna, swordfish and marine turtles. Most jellyfish can cause painful stings by discharging their stinging capsules, which are armed with toxins. The stinging capsules are usually arrayed on their tentacles which they trail behind them. These tentacles can be very long. The tentacles of the dreaded box jellyfish – a species which, fortunately, is not found in the region – can attain lengths of several metres. The average length of tentacles of the species found in the western Indian Ocean is about 30 centimetres. If stung, the pain is typically severe, but of limited duration. Chiropsalmus sp. is probably the most dangerous species in the region. Its sting can lead to shock, difficulty in breathing, abdominal cramps, profuse sweating and can even ultimately lead to death, particularly in children. Its bell is approximately 14 centimetres wide and ten centimetres high and covered with stinging warts. There are up to nine tentacles on each corner of the bell. The animal is occasionally found in inshore waters.

The Sea Nettle (Chrysaora quinquecirrha) is a transparent to pale-pink jellyfish which grows up to 25 centimetres wide. It can be recognised by the sign of a compass on top of the bell. It has four separate mouth-arms, each up to 50 centimetres long, with frilled edges. Its sting can be severe.

The Portuguese Man-of-War (Physalia physalis), which you may see floating along the surface, is not a jellyfish. Rather, it is a colony of polyps, equipped with a gas float. The float can grow up to 15 centimetres, is of a bluish-purplish colour and has a crest. Its strings of batteries of nettle cells can be up to five metres long. Its sting is also severe.

Approximately 50 percent of the jellyfish species known from the region can sting severely. They are less venomous than the Chiropsalmus, but it still would be wise to keep an eye out for all of them. Jellyfish are hard to identify in the water, particularly by a non-specialist, so a good rule is not to enter waters where jellyfish are present.

Precautions and treatment

Divers will be protected from jellyfish stings by their wet suit.

When snorkelling it is a good idea to wear a long shirt and pants, or alternatively a thin Lycra suit (also termed “stinger suit”). In addition to protecting you from stings, such apparel will also provide protection against sunburn. Swimmers are the highest risk group for jellyfish stings. Do not swim in waters where there are jellyfish. A good indication are beaches where jellyfish have been washed onto the shore.

If stung, try to keep your calm and get back onto the boat or shore. Carefully remove the remaining tentacles with the help of forceps, a piece of wood or shell. Be very careful not to touch the tentacles! Even when the jellyfish is dead, the stinging cells on the tentacles continue to fire. Wash the affected area with normal household vinegar. (This renders the nettle cells inactive.) Remaining stinging cells, which may not be visible, should be removed by applying a cream or lather (from shaving foam, baking soda paste, talcum powder or flour) and then shaved off with a sharp edge like a ruler or a knife. Often sprinkling sand on the affected area and removing it by the same method will do the job as well. In severe cases, particularly if systemic symptoms start to occur, seek medical help.


There are more than nine species of stingrays in the region. They inhabit inshore areas and often bury themselves in the sand in shallow water.

Stingrays have a tail armed with one or two serrated spines equipped with venom. The spines are sharp, hard and bony, and the two grooves on the underside of each are filled with a venomous tissue. If approached, the ray sometimes displays threat behaviour by raising its tail. Rays won’t attack a human, but may use their spines to protect themselves if they are accidentally stepped on. The tail will flip up and the spine can become embedded in your foot or leg. Wounds may be lacerations or most frequently only a small cut.

Typically a sting will cause burning and intense pain which will increase within the following 30 to 60 minutes. The area around where the victim has been stung will start to swell up and to discolour – initially it will turn grey, then blue and finally red. Nausea, vomiting, diarrhoea, an increased heartbeat and panic attacks accompanied by profuse sweating might ensue.

Precautions and treatment

There is no known antidote.

Use suitable footwear and take care when walking in shallow water, over rocky seabeds and in coral areas.

Avoid swimming over the top of stingrays in shallow waters.

Do not handle injured animals.

If stung, rinse the affected area in fresh water and then immerse the wound in near-scalding water. This will relieve the pain and help to break down the venom.

Treat cuts for infection.

Do not attempt to remove the sting, but seek medical help, which will include removing the sting surgically.

Stonefish, lionfish and scorpionfish

These species of fish possess venomous spines and/or fins. Stepping on or handling any of these shallow-water species can result in extremely painful wounds. A serious dose of venom from the stonefish can result in death within an hour. The pain is excruciating, immediate and can last for days. There are no antidotes for the poisons of the lionfish or the scorpionfish. Stonefish anti-venom has been produced by the Commonwealth Serum Laboratories in Melbourne, Australia, but the chances of finding it in the western Indian Ocean region are slim.

The stonefish (Synanceia verrucosa) and the raggy scorpionfish (Scorpaenopsis venosa) look similar on first sight, if you manage to spot them at all – they are extremely well camouflaged. The main danger is that these fish are so hard to see as they blend into the background.

The stonefish can grow up to 40 centimetres in length with a squat body and warty brown-to-red mottled skin. It has large fleshy pectoral fins and a row of 13 strong dorsal spines. The scorpionfish is smaller and can grow up to 18 centimetres long. It is mottled brown, red and white with numerous fleshy lobes around the head and sides towards the tail.

The Stonefish is found in shallow pools, on reef flats and on reef slopes. The raggy scorpionfish prefers sheltered reefs and coral patches. It is often found resting on corals and amongst algae.

The handsome lionfish (Pterois sp.) is also venomous, and you should not make an attempt to catch or handle it. It is very distinct in appearance with its long dorsal and pectoral fins. It prefers lagoons and coral reefs as a habitat and is often found in sheltered harbours. During the daylight hours, the Lionfish tends to hide. However, in the late afternoon it becomes active and can present a danger. It is especially important to warn children from playing close to sea walls and from reaching into sheltered areas where these fish may live.

Precautions and treatment

Wear suitable footwear.

Avoid touching any of these fish, either alive or dead.

If stung, the victim should be calmed, as any exertion will only spread the venom around the body faster.

Near-scalding water should be used to break down the venom.

The wound should be treated antiseptically.

If symptoms become systemic, cardio-pulmonary resuscitation (CPR) may be necessary.

Seek medical attention immediately.

Cone shells

Cone shells (Conus spp.) are characteristic cone-shaped shells with short spires and smooth surfaces. They are attractive and come in a large variety of colours and patterns.

Cone shells are carnivorous and prey on fish, molluscs and worms. They posses a venom-filled dart which they use to spear and paralyse their prey; the venom is a very powerful neuro-toxin which can be lethal to humans. When stung, symptoms include localised numbness, stiff limbs, blurred vision, swelling and paralysis which can progress to respiratory arrest.

Precautions and treatment

Do not pick up cone shells!

If someone has been stung, immobilise the affected body part and apply a tight compressive bandage directly onto the wound. (Ensure it is not so tight that it hinders circulation.)

Cardio-pulmonary resuscitation (CPR) or assisted ventilation may be necessary.

Seek qualified help immediately.

Animals that Bite

There are a number of predatory sea creatures in the Indian Ocean which have the potential to bite humans and inflict serious wounds. The main ones are: sharks, barracudas, moray eels and sea snakes.

This must be spelled out very clearly: There are very few predatory animals that will bite you without being provoked. This also applies to sharks, which have been demonised for centuries. Equipped with some knowledge about their behaviour, you may enjoy the privilege of sighting them without coming to any harm.


The majority of sharks, including the reef sharks that you are most likely to see, are generally harmless. They feed on small fish, benthic invertebrates or plankton. Shark attacks are very rare. Based on the International Shark Attack File, there have been an average of only six fatal attacks worldwide per year. Although there are remote areas of the world where a shark attack might go unreported, death by shark is sensational enough to come to wide attention, so you can have some confidence in this figure. But even if the number of fatal attacks were 20 percent higher, it would still be a very rare occurrence. The movie Jaws formed the public view that sharks kill humans. In fact, there are only a very few species which account for attacks on humans. Some of these species are found in the region discussed here, and you should be aware of them.

The most dangerous sharks in the region are the tiger shark (Galeocerdo cuvier), the mako sharks (Isurus oxyrhynchus) and the great white shark (Carcharadon carcharias).

The tiger shark can grow to a size of around six metres or more. It is named for its dark stripes on its grey back, which are pronounced in juveniles, but which become pale or disappear in large adults. Its very wide mouth, broad nose and barrel chest are distinctive. Adult tiger sharks spend their days beyond the reef edge at depths of up to approximately 150 metres, but at certain times of the year they also come inshore during the day. They are active at night, and enter shallow reefs and lagoons after dusk to feed. Generally tiger sharks are sluggish, but they can move quickly when feeding and should be treated carefully on the rare occasions when they are sighted. If you see one while diving, calmly leave the water, keeping it in sight at all times. It is uncommon and rarely seen.

The mako is an offshore species, so it is rarely encountered, but may be sighted by open-water divers. It can grow up to around four metres long and is spindle-shaped with a long conical snout, short pectoral fins and a crescent-shaped caudal fin. Makos are dangerous and have attacked divers. However, attacks on fishing boats, when an angry mako leaps into a boat after being caught on a fishing line, are more likely to occur.

The great white shark, which is also called the white shark or white pointer, usually prefers cooler waters, but occasionally enters tropical waters. Here it is rare. It can grow up to more than six metres long. It is a robust, torpedo-shaped, conical-snouted species with a normal assortment of dorsal, anal and paired fins. The upper and lower lobes of its tail are almost equal in size.

Great whites are responsible for the majority of unprovoked attacks on people in cool waters, and they can kill humans.

It is highly unlikely that you will see either a tiger shark, a mako or a great white. The most likely sharks that you will come across are reef sharks. They are shy and usually avoid divers, but if you stay in their territory for too long some species will display typical threat behaviour. Their usually elegant and smooth movements become jerky; they arch their backs and point their pectoral fins downwards. At the first signs of such a display you should retreat calmly while always keeping the shark in your sight.

Precautions and treatment

Sensible behaviour around sharks and other large fish can minimise the risk of attack.

Consult local people before entering unknown waters; do not swim in waters where sharks are known to be a problem (e.g., near abattoir outlets) or in muddy estuarine waters.

Do not carry dead or bleeding fish in the water, be cautious when spearfishing and leave the water if sharks come close or exhibit aggressive or unusual swimming motions (e.g., back arching in some reef sharks).

Don’t swim at dawn, dusk or at night, which is when sharks are most active.

Avoid swimming with an open wound or while menstruating, as sharks are attracted by blood and other bodily fluids.

Swim in groups, never alone.

Most importantly: do not panic. Most approaches by sharks are motivated by simple curiosity. Do not assume that you are in trouble.

If somebody is attacked, remove the victim from the water. Treat him or her for shock, stop any bleeding and treat cuts. Beware of secondary infections. In case of major wounds, seek medical advice immediately.


Barracudas (Sphyraena sp.) are elongate, silvery fish with two widely spaced dorsal fins, a pointed head with a large mouth and long knife-like teeth. The largest species is the great barracuda (Sphyraena barracuda) which can grow to a length of 1.90 metres. Other species attain a body length of around 75 centimetres to 1.50 metres. They are voracious predators of other fish. Most species school during the day.

There are differing opinions about the aggression of barracudas. In the Caribbean they are considered aggressive, whereas they are considered less aggressive in the Indian Ocean. Throughout the world barracuda attacks are rare. Barracudas will usually keep their distance from swimmers and divers unless they are attracted by anything shiny such a jewellery and dive knives. Then they will circle you curiously. They might try to have a go at the shining object, but it will usually be a half-hearted attempt.

Precautions and treatment

If you see a barracuda, conceal anything shiny that you may be wearing. This may include jewellery, a dive knife, etc.

If one tries to attack you, try to give it a short blow with your snorkel or anything else that you may have at hand.

If the attacks persist, consider terminating your dive and return to the boat.

Any wounds need to be treated antiseptically.

Moray eels

Moray eels are quite a common sight in tropical waters. They inhabit shallow lagoons and seaward reefs and hide in crevices during the day, allowing just their head to emerge. Their mouth is kept open to ventilate the gills, giving full view to their sharp teeth. At night they become active. An amazing sight during a night-dive is a large moray swimming by on its hunting spree, looking for fish and crustaceans. They are generally docile, but can get very aggressive if you come too close or even go so far as to stick your hand into their home. Moray feeding is a popular tourism attraction, but it has its risks. The problem is not only the strength of a moray’s jaws and the sharpness of its teeth, but also that its bite can lead to blood poisoning. It is thought that this is caused by the bacteria within its jaws.

There are several species of moray in the region. One is the masked moray (Gymnothorax breedeni), which is considered aggressive. It grows up to 75 centimetres in length, and the black marks behind the eye and on the corner of the mouth are distinctive. The much larger honeycomb moray (Gymnothorax favagineus) is also occasionally seen and can grow up to three metres. It is covered in large black spots on a white base, creating a kind of honeycomb pattern. The zebra moray (Echidna zebra) attains a length of around 1.50 metres. It has a robust, compressed body, blackish-brown in colour with numerous narrow, yellowish, vertical bars.

Precautions and treatment

Do not put your hands or arms into any crevices, as they might be the home of a moray.

Some morays are aggressive even if they are not defending their territory. If you encounter a free-swimming one, give it plenty of space to escape. Do not try to corner it.

Any bites should be disinfected and treated for secondary infection.

Sea Snakes

Sea snakes are quite commonly seen in Australasia, but rarely encountered in the western Indian Ocean.

Sea snakes are back-fanged and have such tiny mouths that their potential to bite a human is limited. On the Great Barrier Reef in Australia, dive students are advised to keep their fingers pressed together or to make a fist and to place their mask strap over their ear lobes when sea snakes are around. The rationale behind this is that fingertips and earlobes are a manageable target for a sea snake.

The venom of sea snakes is very powerful and is amongst the most effective in the animal world. If enough venom is injected into a human, death can result. Symptoms usually develop within eight hours and include paralysis, weakness, blurred vision and respiratory difficulties.

Precautions and treatment

Many sea snakes are very curious and may approach you and even wrap themselves around your dive tank, your arm or leg. This will cause no harm, and you should remain calm and wait until they’ve satisfied their curiosity.

It is wise to cover your ears with the strap of your mask and to keep your hands in fists to cancel out the possibility of being bitten there.

If bitten, immobilise the affected part of the body and apply a tight compression bandage directly on the wound. Do not remove the compress until the victim is in hospital care.

Anti-venom is the definitive treatment.

Poisonous Fish

WorldGuide continues its look at dangerous animals in the Indian Ocean with this investigation of poisonous creatures.

Pufferfish and boxfish

A number of reef fish are poisonous in that they possess toxins which make them unpalatable. Toxicity may be due to substances produced by the fish itself, or to substances ingested with other organisms. Pufferfish and boxfish have highly toxic skin and viscera, a characteristic which protects them from predation. The toxin, tetrodoxin, is among the most powerful poisons known and is responsible for many fatalities throughout the world. It is not detectable and persists after cooking or freeze drying. The Japanese cherish the Fugu, a genus of pufferfish, despite this toxicity – or in fact because of it. Specially licenced chefs can prepare and sell such fish to the public. Small amounts of the poison, which is contained mainly in the liver and the ovaries, produce an especially desired tingling sensation to the tongue. Every year a number of people die because they underestimate the amount of poison in these fish parts.

Precautions and treatment

Refrain from eating pufferfish and boxfish. There is no specific treatment.


Ciguatera is a prevalent form of serious fish poisoning. It is a toxin that may be present in a wide variety of fishes, but reaches its highest concentrations in the piscivorous fishes at the top of the food chain. It does not affect the fish themselves, but can cause extreme harm and even death in humans if the fish is eaten. Symptoms occur 15 minutes to 24 hours following ingestion and can vary from a tingling of the lips and extremities, rashes and/or headaches in the mildest cases to reversal of the sensations of hot and cold, abdominal pains, muscular weakness, vomiting, diarrhoea, shortness of breath and even cardiac arrest. There is no known cure, and its greatest danger is the unpredictability of its occurrence in food fish.

The toxin is produced by a species of small, bottom-dwelling, single-celled alga, the dinoflagellate Gambierdiscus toxicus, which colonises damaged reefs, rocks and filamentous algae. Gambierdiscus is grazed on by herbivorous fish which are in turn eaten by piscivores. Since the toxin is not metabolised, it accumulates in the flesh and particularly in the liver and the reproductive organs. Each time a predator eats a small fish, it consumes its victim’s lifetime supply of the toxin. Consequently the higher the fish is in the food chain and the older it is, the more toxin it will contain.

Precautions and treatment

The occurrence of ciguatera varies from region to region. Some species seem to be prone to it more than others. Unfortunately, knowledge on which species are risky and which aren’t is sketchy. In the western Indian Ocean region, the red snapper (Lutjanus bohar) and moray eels are the most frequently implicated species and should never be eaten. A good rule of thumb is to avoid eating large fish in areas where ciguatera is known to exist.

It is wise to observe local practice: If the local population avoids eating a particular species of fish, you should avoid it as well.

If you are out fishing on a private yacht, do not assume that the crew will be able to offer expert advice on your catch.

If symptoms of poisoning occur, induce vomiting immediately, apply antihistamine injections and seek intensive medical care.

Other Dangers

WorldGuide continues its look at dangerous animals in the Indian Ocean with this survey of a number of miscellaneous organisms which have the potential to harm you. Whilst they are not as dangerous as those mentioned in the previous sections, they can still cause serious discomfort. The main ones are: corals, fire corals, hydroids, swimmer’s itch, sponges, biting worms and fire worms, octopuses, sea urchins, crown-of-thorns starfish, rabbitfish, catfish and surgeonfish.


Corals belong to the phylum of Cnidaria. This phylum also includes hydroids and the larger jellyfish. One unique and characteristic feature of all cnidarians is the presence of cnidae. These are specialised cells – stinging cells – which are mainly used in defence or to catch prey.

That scratches and cuts by corals are painful and take a long time to heal is due to these stinging cells.

Precautions and treatment

Do not touch corals.

If you get scratched or cut, wash the affected area with vinegar.

Fire corals

Fire corals (Millepora sp.) are not corals at all, although they look like them with their branching calcareous skeletons. They belong to the class of hydrozoans, are found on most coral reefs and can form extensive colonies of up to two metres in diameter. They display various growth forms – from fine branching domes, to encrusting sheet-like or laminar characteristics. They are brownish, greenish or grey, often with a pale-yellow hue.

Fire corals can produce a painful localised welt when they are brushed against. This welt disappears rapidly, usually after one to two hours, unless the victim is particularly sensitive to it; for example if he or she has been exposed to fire coral before or tends to develop allergic reactions.

Precautions and treatment

Do not touch anything that looks like a coral.

Treat welts with vinegar-soaked bandages.


Feather and stinging hydroids look like delicate feathery trees and can grow up to one metre tall. They prefer to grow on hard substrates, such as rocks or coral. Upon contact with these organisms your skin will burn and itch. Sometimes blisters may develop.

Precautions and treatment

Do not touch hydroids. If stung, cover the affected areas with vinegar-soaked bandages.

Swimmer’s itch

In shallow, sheltered water you may occasionally experience a stinging sensation on your skin. It is not quite clear what exactly causes it, but it is thought that larval stages of medusae and hydroids are involved. There are usually no after-effects, but occasionally an itch can persist and a rash can develop.

Prevention and treatment

Always wear a stinger suit when snorkelling.

If you develop a persisting rash, apply a local antihistamine ointment to the affected area.


Many sponges induce dermatological reactions and rashes. Sponge spicules, which are a feature of several species, are particularly nasty, causing severe irritation if they remain embedded in the skin. Sponges of the genus Biemna are known to cause swelling, inflammation and intense itching which can last for days.

Precautions and treatment

Do not touch sponges.

If you’ve come into contact with one, wash the affected area with vinegar and apply “Tiger Balm” or “Deep Heat”. Use Sellotape to remove any embedded spicules and apply hydrocortisone and antihistamine if an irritation persists.

Biting worms and fire worms

Some predatory polychaete (meaning “many bristle”) worms which are armed with fangs can bite. Others, known as fire worms, are covered in dense, fine spines which can easily become embedded in the skin and may produce a burning sensation and rash. When turning over stones or walking barefooted you may come in contact with these worms.

Precautions and treatment

Wear suitable footwear.

Avoid touching any polychaetes.

If you’ve come into contact with a biting worm, apply disinfectant.

If you’ve come into contact with a fire worm, remove the bristles with Sellotape and apply vinegar.


The octopus can deliver a painful bite.

Precautions and treatment

If you have no experience with octopuses, do not handle live ones.

If you are bitten, clean the affected area with soap and water, apply disinfectant and a loose bandage or dressing, which should be changed regularly.

If swelling and reddening worsens and lymph glands swell, seek medical advice for appropriate antibiotic treatment (e.g. Amoxicillin, Co-trimoxazole). Stay out of the water until healing is complete.

Sea urchins

The most common incident involving a marine creature in the region is stepping onto a sea urchin. In most cases, the spines break off in the skin and are hard to remove. If they cannot be removed they can be uncomfortable, but usually dissolve in the skin within a few weeks. Pain is very localised and lasts up to 20 minutes. Contact with the few toxic species is much more dangerous. Skin contact with Asthenosoma sp. and Toxopneustes sp. causes venom discharge which is extremely painful and can lead to numbness, general paralysis and respiratory distress.

Asthenosoma varium is a distinctive sea urchin which is usually found on shallow reefs. It has a test (body) of around 15 centimetres in diameter. The length of the spines is around 3.5 centimetres, and its body is covered in short secondary spines, each tipped with a small contractile poison sac; it has a few scattered longer primary spines, as well. The secondary spines may bundle together into five or six small, squarish blocks resulting in a distinctive geometrical pattern radiating from the upper central area. This sea urchin is mostly nocturnal. Toxopneustes pileolus, which is also found on shallow reefs, but also in seagrass beds, is similarly easy to identify. The diameter of its test is around 15 centimetres and the length of its spines is up to three centimetres. The short spines are red at the base, with green and white tips. The test is pink, low and circular. The stalk of the pedicellariae is about three times the spine length and topped with a three-bladed, flower-like pedicellariae up to four milliimetres across when fully opened. These have poisonous sacs attached containing a poison which is potentially lethal to humans.

Precautions and treatment

Wear suitable footwear when walking in the sea, especially in lagoons with rocks and corals.

If you’ve been pricked by toxic species, immerse the affected area in near-scalding water (just below 50 C). This will help to break down the poison by de-naturing the poisonous proteins. It also contributes to pain relief.

The local people apply the sap (milk) from young, unripe papayas, which acts as an astringent.

Cardiopulmonary resuscitation (CPR) may be necessary.

Seek medical attention immediately.

Crown-of-thorns starfish

The numerous spines covering Acanthaster planci are venomous and the spines themselves can persist in the skin for months. This starfish is unmistakeable. The starfish can grow up to 70 centimetres in diameter and has a spiny, circular body with 20 to 30 short arms. Its colour is variable – it is often red and green or various shades of red and pink. The adults feed voraciously on living coral, can occur in high densities and can be responsible for large areas of dead coral.

Precautions and treatment

Do not handle the starfish.

If you’ve been in contact with one, remove the easily extractable spines and use near-scalding water to break down the venom.

Surgeonfish, rabbitfish and catfish

There are over 30 species of surgeonfish in the region. They have an oval body with a small mouth and tough skin with tiny scales. The sharp spine on the base of the caudal (tail) peduncle is clearly visible.

Surgeonfish are numerous, for example, in the Maldives. When you are swimming or snorkelling, this type of fish will keep its distance. However, should you or your children feed the fish with bread as some tourists do, you may cause a feeding frenzy to break out. If you are in the water at the same time, the fish may brush up against you and injure you with their razor-sharp spines. Another danger arises if you are fishing and manage to hook a surgeonfish. Be sure to exercise great caution when removing your catch from the line – watch out for its spine.

Rabbitfish and catfish have poisonous dorsal spines that inflict painful wounds when live or dead fish are handled. The tail peduncle of surgeonfish is armed with an extremely sharp, moveable spine, partially covered by skin. It can cause lacerations.

Rabbitfish have oval bodies with very small scales and smooth skin. Siganus sutor, the whitespotted rabbitfish, can grow up to 45 centimetres. Its colour is uniform olive-green in the water; it turns brown when it is removed from the sea, and black bars and numerous white spots then become visible. Found in inshore areas, especially seagrass beds, it grazes on algae and seagrass.

Catfish have elongated bodies and eight barbels around their mouth. Their second dorsal, caudal and anal fins run together. They are found in shallow estuaries and coastal waters and on coral reefs, and juveniles can form dense aggregations of hundreds of individuals.

Precautions and treatment

Be extremely careful when handling live or dead fish.

If pricked or cut, immerse the affected area in near-scalding water.

Vinegar is effective against catfish wounds and may relieve rabbitfish wounds.

Surgeonfish wounds should be irrigated with fresh water and dressed lightly.