Explore the Deep Sea
Life in the Deep
A rich variety of creatures can be found around hydrothermal vents in the deep ocean.
Deep-sea mussels and clams
Like tubeworms, several deep-sea mussel and clam species living near deep-sea vents contain in their tissues symbiotic microbes which manufacture food for them. The body structure of these animals differs from related species of shallower waters: the deep-sea vent species typically have bigger gills, and some have smaller guts. The gills hold the microbes: larger gills mean more microbes, hence less need for a digestive system. But species which retain functional guts can live for a short time even if vent fluids stop jetting from the seafloor. This could help them survive near vents which are fitfully active.
Shrimp are found in many deep-sea vent sites. Sometimes (e.g. in the mid-Atlantic), thousands or even millions teem in a small area. The shrimp eat microbes living free on the rocks and in the water column; they also play host to other, "symbiotic" microbes that manufacture food for the shrimp. In turn, other animals eat the shrimp—including other species of shrimp, fish, crabs, and anemones.
Several different barnacle species have been discovered near deep-sea vents. Some species are "living fossils" that evolved over a hundred million years ago (before the dinosaurs went extinct). In several species, adult barnacles grow on stalks attached to rocks; in other species (e.g. Neolepas zevinae, in the Pacific Ocean) individuals grow on top of one another, forming low "hedges." Barnacles are not known to contain symbiotic microbes—rather, they filter their microscopic food out of the water.
Crabs and lobsters
Crabs and lobsters feed on other organisms found around deep-sea vents. Some eat tubeworms, mussels, clams or shrimps; others eat microbes. Some species of crab are very noticeable in photographs of the seafloor because they are whitish and fairly large. Crabs are often among the first animals to colonize newly-formed vents.
Even more animals
Snails, limpets, octopus, fish, copepods, amphipods, anemones and many other types of animal are found around some deep-sea vents. As with the other groups of animals found in the deep sea, exactly which species we encounter depends where we are: what ocean we are in, what depth we are at, and the composition of the seawater.