Dangerous Sealife

Dangerous Sealife

© Copyright Congratulafins

Breathtaking scenery, various outdoor and water sports, and the opportunity to encounter wildlife attracts a lot of people to visit the beach every summer.

Sealives are fascinating to observe because they have evolved in all these different ways to adapt to different environments, defend from predators, and hunt for prey. Adaptations include poisons and venoms, sharp teeth and stings etc. Though not intended to harm humans, one might get hurt during an encounter if not aware. Hence the title “Dangerous”. We call them dangerous because the defence mechanisms of these species are powerful enough to inflict injuries on humans. Not because they are on a mission to hurt us. So don’t let this stop you from exploring the ocean, just a little bit of knowledge can help you avoid unpleasant injuries and experience nature more safely.

Close encounters with sealife can inflict two types of injuries: One type is physical bites, cuts, and bruises. The other type is chemical, where venoms or poisons get on or into human bodies. The simplest way to avoid injuries is to give sealives their space and not provoke them and to wear protective gear like rash guards and gloves to put a barrier between you and venomous substances.

Now that we’ve got the general idea, let’s take a closer look at the individual species and learn what is dangerous about each individual, how to avoid getting hurt, and what to do in each scenario.

Since most people think sharks are the most dangerous animal in the sea, let’s talk about them first and set the record straight:

There are over 500 species of sharks in the world, and more than 300 of them are under 3 foot long. The average length of all sharks is 4 ft. Smaller than an average adult. Therefore most sharks steer away from humans when they see us. Only 13 species of sharks are known to bite humans: Shark species that may bite include the Great White Shark (Carcharodon carcharias), Tiger shark (Galeocerdo cuvier) and Bull shark (Carcharhinus leucas). However, they happen rarely: there are on average 10 global cases of shark attack fatality annually.
On the contrary, shark encounters are often on the bucket list for many divers — and can be done safely: Stay calm, move slowly, and never harass a shark.

Other animals that bites:

Although triggerfish (Family Balistidae) have small mouths, their powerful jaws can inflict a very painful bite. A nesting female triggerfish will behave aggressively when they feel threatened. When you see an angry triggerfish frantically chasing you or charging at your fins, you probably have gotten too close to her nest. Swim away calmly and stay close to the bottom while doing so, because a triggerfish’s territory expands upwards.
The trigger fish in the picture is a clown triggerfish (Balistoides conspicillum).

Moray Eels:
Moray eels are the largest eel species. They can grow up to 3-4 meters long. Eels have a mouthful of fangs, and their bites can be incredibly painful because of the “pull back pattern”. Moray eels also have venom in their mouths, temporary paralysis of the bitten area can occur. If not cared for quickly and properly, these bites can easily become infected. Treatment: Clean the injured area with freshwater, attend the wounds, and pain control. In case of severe bites, seek medical attention immediately.
The moray eel in the picture is a Green Moray Eel (Gymnothorax prasinus).

Sea Snakes:
Sea snake (Subfamily Hydrophiinae) bites are rare, and most sea snakes’ fangs are not long enough to penetrate through a wetsuit. However, we want to mention it because their bites are highly venomous and can be a life-threatening medical emergency, and requires immediate medical care. The death rate for sea snake bites is 3%. Immediate treatment is to clean the wound with soap and freshwater(if available). Apply pressure bandage to the whole extremity involved in the bite to slow down the venom traveling to the heart.Try not to move the extremity involved if possible, and seek medical attention.
The sea snake in the picture is a Banded Sea Snake (Laticauda semifasciata).

Blue-ringed octopus:
All octopuses and cuttlefish, and some squids are venomous.
The blue-ringed octopuses (genus Hapalochlaena) are among the most venomous animals in all of the world's oceans. If bitten, call emergency services immediately. Lie down or stay as still as Apply an elastic bandage to the bitten area. Bandage the entire limb as tightly as possible and prepare to perform cardiopulmonary resuscitation (CPR) if needed.
The octopus in the picture is a Blue-ringed octopus (Octopus maculosus).

The following 2 cephalopods don’t have venomous bites, but are also venomous:
Striped pajama squids (Sepioloidea lineolata) excrete toxic slime when threatened to protect themselves.
Flamboyant cuttlefish (Metasepia pfefferi) is not only venomus but also the only cuttlefish to have deadly poisonous flesh.

The best defense from being bitten is to stay aware of your surroundings and ensure animals have their space. Never approach and never touch. Also, be careful where you put your hands. Gloves, and wetsuits can also offer you some protection.

General rules to treat a marine bite: Rinse wounds with clean water, control bleeding, seek medical treatment.
All bites have a high potential for infection and should be evaluated by a doctor.

Now, let’s talk about stings:

Stingrays are shy and peaceful. They do not represent a threat unless startled or threatened.. Most injuries occur in shallow murky waters when people accidentally step on them. Stingrays’ defense mechanism consists of a serrated barb at the end of its tail with venom glands located at the base of the barb. To prevent getting stung, be more mindful when walking in the sand. Avoid walking barefoot in shallow or murky waters. Immediate treatment is to clean the wound with freshwater, and control the bleeding. Seek medical attention immediately. If that is not possible, soaking the wound in hot water (upper limit of 113°F/45°C) for 30 to 90 minutes can alleviate the pain.
The stingray in the picture is a Bluespotted ribbontail ray (Taeniura lymma).

Sea Urchins:
Sea urchins are abundantly found on shallow rocky marine coastlines. The primary hazard associated with sea urchins is contact with their spines.The spines can penetrate boots and wetsuits, puncture the skin and break off. They are also hollow and fragile, making extraction of broken spines from the skin difficult. Very few species of sea urchins such as the Flower sea urchin (Toxopneustes pileolus) contain venom. Hot water immersion may help denature superficial toxins. Immediate treatment is to remove any superficial spines with hands or tweezers. Spines embedded deeper should be handled by medical professionals. Wash the area thoroughly and gently. Apply antiseptic or antibiotic but do not close the wound with tape or glue. Medical evaluation is highly recommended. The sea urchin in the picture is a Black Sea Urchin (Black Sea Urchin).

Crown-of-thorns sea stars:
Crown-of-thorns sea stars get their name from looking like a large crown made of thorns. The sharp, thorn-like spines can easily pierce through skin and release potent venom. Treat sting by soaking the wound in hot water, remove stings, and seek medical attention.

Bristle Worms:
Bristle worms (Order Phyllodocida) can be found on rocky beaches. Although not aggressive, they may bite when handled, and the bristles or spines can penetrate the skin when touched.The spines penetrate the skin like cactus spines and can be difficult to remove. Treatment: Remove bristles with adhesive tape or tweezers. Rinse wound with 5% acetic acid (Vinegar) or 70% isopropyl alcohol (rubbing alcohol). If there are signs of infection, consult a healthcare professional.
The bristle worm in the picture is an Orange Fireworm (Eurythoe complanata)

Pufferfish and Porcupine fish:
Pufferfish (Tetraodontidae) and porcupine fish (Diodontidae) belongs to Family Diodontidae. They will puff up and erect the stings when threatened. Pufferfish are also poisonous, containing tetrodotoxin, a potent neurotoxin, in the ovaries, liver, intestines, and skin of the fish. Poisoning occurs from eating pufferfish meat.
The puffer in the picture is A Long-spine porcupinefish ( Diodon holocanthus).

Fish with venomous stings include: lionfish (Genus Pterois), scorpion fish (Genus Scorpaenopsis), striped eel catfish (Plotosus lineatus), and basket fish (Genus Siganus). Treatment is to clean the wound in freshwater, stop bleeding, and soak the wound in hot water (upper limit of 113°F/45°C) for 30 to 90 minutes.
The lion fish in the picture is a Zebra Lionfish (Dendrochirus zebra), the scorpeon fish in the picture is Scorpaena neglecta, the basket fish in the picture is a Rabbitfish (Siganus fuscescens).

Surgeonfish (Family Acanthuridae) has spines near the tail that can inflict cuts or lacerations. The surgeonfish in the picture is a palette surgeonfish (Paracanthurus hepatus).
Three-striped tiger fish (Terapon jarbua) has sharp spines on its gill covers, which can wound a careless handler.

Cone snails (Genus Conus) have conical shells with beautiful color patterns. People often pick them up because they are beautiful. Cone snails possess a harpoon-like tooth capable of injecting a potent neurotoxin that can be dangerous to humans therefore is best not to touch them. If bitten, clean the wound in freshwater, apply the pressure immobilization technique and immediately seek medical attention.
The cone snail in the picture is a Textile Cone Snail (Conus textile).

Some of the most beautiful and seemingly harmless marine invertebrates are among the most hazardous.Snorkelers and divers may unintentionally come into contact with free-swimming jellyfish, hydrozoans or touch hydroids and fire coral. They are armed with stinging cells generally known as nematocysts.

For jellyfish stings, immediately flood the entire stung area with lots of vinegar for at least 30 seconds. DO NOT use fresh water. If pain relief is required, apply a cold pack only after vinegar
has been applied. Urgently seek medical aid at a hospital if symptoms are severe.
The jellyfish in the picture is a box jellyfish (Carybdea brevipedalia).

Sea slugs:
The Blue Dragon Nudibranch and other Aeolid Sea Slugs eat jellyfish and collect it’s venom to store in their own skin and release the venom when they are in danger.
The sea slug in the picture is a Blue Dragon Nudibranch (Glaucus atlanticus).

Portuguese man-of-war:
Portuguese man-of-war (Physalia physalis) is characterized by blue gas-filled bladders and long tentacles that drift on the surface of the ocean. Though it looks like a jellyfish, it is hydrozoans and is more closely related to fire coral. It is actually a colony composed of up to four different types of polyps. If stung, avoid rubbing the area. Remove the tentacles with tools. Once the tentacles and any remnants have been removed, flush the area with seawater (NEVER use freshwater!). Immerse the affected area in hot water (upper limit of 113°F/45°C) for 30 to 90 minutes. Immediately seek medical evaluation.
The fish that lives in it is a Man-of-war fish (Nomeus gronovii).

Fire Corals and Hydroids:
Fire coral (Genus Millepora) looks like coral, it is a member of the class Hydrozoa and more closely related to jellyfish and other stinging anemones. Hydroids (Genus Aglaophenia) look like tiny ferns or feathers. Fire coral and hydroid stings are irritating but not lethal. Use seawater to rinse off the stings and apply rubbing alcohol or ice for pain relief.

Sea Anemones:
Sea Anemone Stings release a poisonous chemical into the human skin through their spine, which can affect the human body.Some sea Anemones to look out for are Armed Anemone (Dofleinia armata), and Tube-Dwelling Anemone (Cerianthus membranaceus). Treatment consists of washing the affected areas with soap and water followed by a vigorous rinse.

Mantis shrimp:
Mantis shrimp pack the strongest punch of any creature in the animal kingdom, with peak impact forces up to 1501 N. The peacock mantis shrimp also has the world's fastest feeding strike of any animal. They also have sharp spines that stab. Fishermen consider the mantis shrimp dangerous and avoid direct contact with them. There are frequent reports of human injuries caused by these crustaceans. They are not dangerous as long as you don’t touch them.
The mantis shrimp in the picture is a Peacock Mantis Shrimp (Odontodactylus scyllarus).

Sources Cited


Trigger Fish:

Sea Snake

Blue-Ringed Octopus:

Sea creature bites:


Crown-of-thorn Sea Star:


Sea Slug:

Fire Coral:


Mantis shrimp:


Sea creature stings:

Link to download DAN’s dive medical reference book “Hazardous Marine Life”:

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