The giant shipworm:
from a ship wreck pirate to a deep see creature
“It might well be monstrous, but that does not mean that it isn’t marvelous.” (President of the Ugly Animals Preservation Society).
Purely this quote made me so happy. First of all, there is a society fighting for ugly animals – how great is that? But wait until you hear what creature their president was talking about. Turns out the world went crazy about a giant shipworm (Kuphus polythalamia) that has just been described and filmed while being flopped out of its tube for the first time. And giant shipworms are marvelous indeed: They are neither worms (they’re a type of mussel), nor are they interested in ships (more on that below). But they are certainly gigantic, at up to a whopping 155cm, pitch black, and live in shell-type tubes which they build from their own secretes. These tubes are buried in mud, with only a small part sticking out into the water. Okay, that’s cool and all…is that why they’re marvelous? Hold on to your shipworms, it’s only getting better. They’re giants in what is a pretty nutrient-poor environment. How do they sustain their body length, tubes and all? Well, they employ hydrogen sulfide. Not only that, they do so without much of a digestive tract!
The giant shipworm has two appendages that stick out of the tube and function as water pipes – one in, one out. The magic happens in between, where the worm is populated by specific bacteria which filter out the gas from volcanic vents to produce the energy necessary to keep their host alive. How would such a system even develop? Well, here’s the thing: no other shipworm has that same system. In fact, the old-school, non-giant shipworm cousins (who are in fact interested in ships, specifically those of the rotten-wood type) feed off wood. Some have some bacteria in their gills to help them do it, sure. In exchange, the bacteria in these worms get some carbon so everyone benefits. But none of these cousins completely rely on bacterial energy production. The giant shipworm has basically outsourced the entirety of its digestive process to bacteria who don’t need carbon from their host but rather produce carbon for it. Even though it remains a mystery how this species developed, this paper has a theory suggesting that “normal run-of-the-mill shipworms” sank under water while happily digging into pieces of wood (maybe from a ship wreck?). Instead of simple dying, one of these sturdy worms continued munching under water and adapted to the new environment. Slowly, a new species of ship worm emerged.