  "I have been bitten by a sea snake and these guys are no joke! They have extremely powerful toxins that they need to overpower their fast and slippery prey." ~ Donald Schultz, Host of WILD RECON
|
BITING NEMO: Sea Snakes Pose More Danger to Fish than Humans
There's a big difference between a dangerous snake and a deadly snake, as any herpetologist will tell you. Members of the Hydrophiidae family — the sea snakes — are classic examples. Most reference books will dryly inform you that sea-snake venom is one of the most toxic chemicals in the world. Those same books will point to LD
50 lists, which rank the toxicity of venom and often show sea snakes defending three of the top five spots. The higher a snake is on such a list, the more deadly its venom. But does that mean the animal actually causes a significant number of human deaths? In the case of sea snakes, the answer is, reassuringly enough, no. No documented deaths from sea-snake bites have occurred in areas such as Australia and Sri Lanka where the animals are common.
Squirming Snake Islands
So why do sea snakes inspire so much fear? For one thing, their numbers are staggering. Some scientists believe that the yellow-bellied sea snake (
Pelamis platurus) is the most abundant reptile on Earth. Across the Pacific and Indian oceans, masses of these snakes form into huge, squirming islands. Fish approach these "islands," looking for protection or a quick meal, only to become meals themselves. It's sneaky, and sneaky is scary.
Despite their abundance, many of the 50 species of sea snakes remain mysteries to the scientific community. It's not clear when and where they give birth, what their diving capabilities are or how far a single snake can roam in its lifetime. What scientists do know is that these animals are wonderfully adapted to life in the open water. Evolution has turned sea snakes into swimming machines, with laterally compressed bodies and paddle-shaped tails. Valved nostrils keep water out. Special glands beneath the snake's tongue do the same with salt. And then there's the venom, made especially potent to ensure a sea snake's prey — fish — is immobilized before it can swim away.
Venom for Three
It's the venom, or the threat of having venom injected into our bodies through needle-sharp fangs, that makes our skin crawl. Doctors call this injection process envenomation, and even though 80 percent of sea-snake bites fail to deliver a full dose, those that do can have dire consequences. Complete envenomation by an adult sea snake introduces enough venom to kill three adult people. The venom contains both neurotoxins and myotoxins, nasty chemicals that wreak havoc on a victim's neuromuscular system. Working to block the transmission of impulses from the central nervous system to the muscles, neurotoxins cause widespread paralysis. Myotoxins attack the muscles, causing myoglobin, a protein that stores oxygen in the muscles, to accumulate in the bloodstream. Both types of toxins go to work quickly, with symptoms typically appearing within two hours of the bite. Within eight hours, myoglobin levels can reach levels that may lead to acute kidney failure and death.
Treatment for sea-snake bites involves intravenous delivery of sea-snake antivenom or, if that's not available, tiger-snake antivenom. One vial of sea-snake antivenom is equivalent to two to four vials of tiger-snake antivenom. And if neither of those are available, doctors will resort to polyvalent antivenom. Polyvalent describes an antiserum containing chemicals to counter the effects of many different venoms.
Of course, the odds are high you'll never need sea-snake antivenom. It's a different matter for fish that frequent the reefs of the Indian and Pacific oceans. For those animals, the sea snake is both dangerous and deadly.
Recommended HSW links: If you're feeling brave enough, learn about more fascinating creatures that bite at HowStuffWorks.com.
Are Komodo dragons' mouths deadlier than cobras' venom?
Do jellyfish have the deadliest venom in the world?
Can a platypus poison me?
How Snakes Work
