When people find out that you are a diver, many of them probably ask you the same question: “Aren’t you afraid of being eaten by a shark?” While your answer will vary depending on your experience and your appreciation for these large predators, you’re most likely aware that while sharks can be a menace, they are rarely the cause of diving accidents. Instead, more divers are injured by small, yet dangerous species that might not even appear to be threatening. Here are some of those most commonly encountered.
Octopus and Squid
While octopus and squid do not attack people, they can bite if provoked. While most species are capable of releasing a mild venom, the beautiful Blue Ringed Octopus is deadly to humans. Found mainly in tidepool environments and shallow reefs in the Pacific Ocean, all the way from Japan to Australia, with heavy concentrations around New South Wales and South Australia, this little octopus grows to a maximum size of just 8 inches. Although it is a highly prized subject for underwater photography, and grows even more beautiful and brilliant when provoked, it releases the neurotoxin maculotoxin, which causes respiratory failure. There is no known antivenin.
Stonefish
The most toxic of all fish species, Stonefish have sharp dorsal fins that are strong enough to penetrate leather and plastic. These fantastically camouflaged fish, which are just about a foot long, won’t attack you – in order to be the unlucky recipient of their venomous sting, you have to grab one, step on one, or otherwise come in contact with one. If this happens though, be prepared for the consequences – left untreated, the sting of a stonefish can cause a huge area of swelling which can lead to tissue death, often resulting in the need for amputation. If you are stung by a stonefish, seek immediate medical treatment.
Scorpionfish
If you dive reefs or wrecks, you are probably familiar with scorpionfish. In all, there are more than 300 different scorpionfish species, many of which disguise themselves to look like rocks or clumps of coral. They have venomous spines, and although their stings are not as dangerous as those of the stonefish, you need to seek medical treatment if stung.
Stingrays
Although most stingrays are large, with their stingers reaching a length of fourteen inches in some cases, there are some smaller stingray species as well. With the Histrix or teacup stingray and the Scobina stingray reaching disc sizes of about a foot, and sometimes smaller, these little creatures are capable of dealing a nasty wallop. While not large enough to cause a fatal injury like the one that killed Steve Irwin in 2006, small stingrays can still cause very painful injuries. The swelling can last for months, and the pain is excruciating. Avoid harassing rays, and shuffle your feet when you’re entering sandy areas, to allow the rays to move out of the way.
Surgeonfish
Beautiful tropical fish that come in about 80 different shapes, sizes and colors, Surgeonfish are equipped with venomous spines. Nowhere near as dangerous as other venomous species, they should still be left alone. Tangs and Unicornfish are both types of surgeonfish. Depending on species, these lovely but poisonous fish grow to be between 6 and 16 inches long.
Crown of Thorns Starfish
Usually found in deeper reef environments and sometimes found on wrecks, the Crown of Thorns starfish should never be handled. Its spines are venomous, causing pain and swelling, bleeding, and in the worst cases, swollen lymph nodes. If spines are not removed immediately, symptoms can continue for as long as several months. These starfish can be found in a variety of colors, and grow no larger than about 25 centimeters across. They’re impossible to miss – their entire bodies are covered in sharp spines that are capable of piercing gloves, wetsuits, and other equipment.
Sea Urchins
Lovely to look at, and beautiful as photographic subjects, sea urchins are sometimes venomous. Their spines deliver a dreadful sting, and if you are on the receiving end, you could find yourself in a surgical suite having spines removed. Never try to pull sea urchin spines out by hand, as you may cause an injury to worsen. Instead, seek emergency treatment.
Sea Worms
There are lots of different types of sea worms living in a variety of underwater environments. Many of these, particularly the more colorful types which are found living under rocks and in coral reefs in the Caribbean and other warm water environments, can cause stinging and painful rashes. If you accidentally come into contact with one, seek medical attention. You may end up with a prescription for antihistamines.
Glaucus, or Lizard Nudibranch
Just one of the many toxic species of nudibranch, the Glaucus Nudibranch is usually between 1 and 3 centimeters long, and delivers a painful sting similar to that of a sea anemone or stinging jellyfish. These beautiful nudis are blue on their dorsal sides and white on their undersides. Take lots of photos, but never, ever touch one.
Fire Coral
One more reason you should never reach out to touch coral of any kind, Fire Coral can look almost identical to other coral species. It is colorful, with invisible tentacles that bear nematocysts like so many other dangerous species do; the effects of coming into fire coral range from stinging to severe pain, and in cases where people have allowed large portions of their bodies to come into contact with fire coral, hours of excruciating nausea and vomiting have followed.
Mantis Shrimp
Mantis shrimp are quite large for shrimp, with the largest recorded specimen coming in at 15 inches long. Named for their resemblance to praying mantises, these shrimp are aggressive when provoked, which has earned them the nickname “thumb splitter”. Their tiny claws are so strong that they have been known to break aquarium glass, and they are capable of inflicting gashes so deep that stitches are required.
While these are only some of the most commonly encountered small, dangerous species, there are many others. Corals, anemones, and sponges, all of which are found at popular dive sites worldwide, are capable of inflicting painful injuries, yet without them, diving would be nowhere near as magical as it is. By learning more about the creatures whose world you visit when you dive, and by keeping your hands and other body parts to yourself, you can enjoy viewing all these incredible animals, and prevent injury, while at the same time practicing good conservation tactics.