Explore the Deep Sea
Life in the Deep
Mouthless, gutless, legless animals that rely on microbes for food.
There are many different types of tubeworm in the ocean. Some are found at cold seeps (where chemicals leach out of the seafloor in the absence of volcanic activity), some on decomposing whale carcasses, and some near volcanoes and vents in the deep ocean.
Each individual tubeworm consists of a soft body surrounded by a tough outer tube of whitish chitin (the same substance that makes up the shells of lobsters and crabs). This tube supports the inner body and protects it from predators (in some species, the tube is leathery, in other species, it is hard). Like plants, adult tubeworms are sessile: they are anchored to one spot, although their top end can move around in the water and can be withdrawn into the tube. Some tubeworms even have "roots": extensions of their body that extend into the sediment.
Tubeworms "eat" without a mouth
Unlike most other animals, a tubeworm lacks a mouth, gut and anus. Instead, it gets its food from millions of microbes living inside it (a bit like a plant gets its food from the choloroplasts which give it its green color). The tubeworm's body reflects the symbiotic (living together) relationship it has with its microbes:
- Instead of a gut, each tubeworm contains a trophosome (a nutritional organ)—a mass of green-brown spongy tissue where the microbes live inside specialized cells.
- The part of the tubeworm furthest from the surface where it is anchored is called the plume. The worm never leaves its tube completely, but it can poke its plume into the seawater above. This organ is specialized to harvest the chemicals the microbes need to manufacture food from seawater. The plume often looks red because it is filled with blood close to the surface (a bit like our lungs).
- At the end next to the seafloor, some tubeworms grow root-like structures. Like the plume, these appear to help the tubeworm absorb chemicals that its microbes use to manufacture food.
Not only can they live under immense pressures deep in the ocean, tubeworms living around volcanoes and vents can tolerate a wide range of temperatures. An individual tubeworm can often experience a range of tens of degrees over the length of its body (or a change in the same place on its body over the course of just a few seconds): from the background chill of most deep water (a few degrees above freezing), to warm fluids drifting out of vents in the seafloor.