A few years ago, a very difficult question was put forward to marine experts; how many species of animals and plants live in the ocean? In the year 2000, a huge census of marine life was put forward, combining the expertise of thousands of marine scientists from 82 different countries. The result: an estimated 230,000 known marine species that have been described as “unique”. Now this was a few years ago, and that number has risen steadily over the past 17 years. Even one of Bunaken’s most famous residents, the Hippocamuspontohi, had yet to be discovered at the time of the census. And most scientists believe this is just a fraction of the total marine species, considering how 95% of the ocean is yet to be explored.
Marine creatures come in all kinds of shapes and sizes, from tiny pygmy seahorses, adorable hairy squat lobsters, colourful Christmas tree worms, to whales larger than a double decker bus. While the ocean is full of bizarre and unique creatures, there are others which could be described as sinister, grotesque, or even terrifying…
There is a large class of marine creatures, known as Polychaete (more commonly referred to as ‘fire worm’, or ‘bristle worm’), with over 10,000 recorded species, however most divers have either never heard of them or know very little about them. Within this class, there is a creature that you could describe as rather ghastly, and it could easily be the star of some Hollywood sci-fi/horror flick.
The Eunice aphroditois, more commonly referred to as the Bobbit Worm, is a large, predatory segmented worm, that dwells in burrows on the ocean floor throughout many parts of the tropics. They use their five antennae to sense where their next victims are, striking in less time than it takes you to blink, slicing through their prey with scissor like fangs and dragging them underground. Apart from their impressive ambush attack, bobbit worms are noted for their unusually large body length. The average length one metre, however there have been specimens discovered in the waters of Australia and Japan that have measured a colossal three metres!
Bobbit worms, like all other polychaete, have harpoon-shaped bristles that can release a toxin that can cause severe irritation to skin. The bobbit worms bristles can even cause permanent numbness if handled. These are merely used for defence, and to allow them to grip whilst crawling over the substrate. Their bite is also venomous, injecting a toxin that stuns their prey, allowing the bobbit worm to catch food much larger than itself.
The species colouration can range from gold-red to dark brown, and lit up with a flashlight, they will reflect a brilliant rainbow pattern. Aside from the five antenna and enormous jaws, they are easy to recognise as the 4th segment is either white, or a paler colour than the rest. As they like to live in sand or rubble, they are most commonly encountered whilst muck diving, and usually at night. There are always exceptions to the rule however, and just recently, one of our guests, John Madsen, along with dive guide Danny, were extremely lucky to encounter a fully grown bobbit worm freely wandering over the reef in the middle of the day. Luckily, John had his camera with him, and was kind enough to share the incredible footage with us.
There is a popular myth surrounding the bobbit worm, that after mating, the female will cut off the male’s penis and feed it to her young. This is supposedly how they got their common name, referring to an incident in the early 1990s, where a woman named Lorena Bobbitt did something similar to an abusive husband. The myth, however interesting it might be, remains just a story, as bobbit worm reproduction is far less interesting. In fact, the worms do not have a penis, and reproduce via ‘broadcast spawning’, where sperm and eggs are released into the waterand fertilisation takes place externally. Individuals may never even encounter a member of their own species, and scientists believe that they reach sexual maturity when they reach around 100mm in length.
While they may not be the ideal inhabitant for an aquarium, they have interestingly been found devastating fish collections after being introduced by mistake. Because coral and rocks for aquariums are frequently collected from reefs, occasionally a juvenile bobbit worm may be amongst one of those rocks, and transferred accidently into an aquarium. There was a famous case at a public aquarium in Newquay, England, where one specimen was eventually discovered after years of mysterious fish disappearances, injuries, and coral damage. The four-foot worm was named Barry, before being moved into his own tank.
Here at Siladen, bobbit worms are quite an unusual sighting, and to see them out of their homes in the middle of the day is unheard of. Our dive team have over 30,000 dives between them around Bunaken Marine Park, and none of them have ever seen anything like what John and Danny were lucky to spot. If you would like to see one of these frightful critters on your next trip to Siladen, your best bet would be to join as many night dives as possible, and head over to muck diving slopes of North Sulawesi. Just don’t get too close!