Snails at vents – how many are there, and what do they feed on?

by Jan Steger

Soon after the discovery of lush life at deep-sea vents, it became clear that snails are very common in this fascinating ecosystem. Today, we know more than 150 different species from vents all around the world, and new exciting discoveries are made every year. Many of these snails do not occur anywhere else in the deep sea, and some live only in small areas. Such species may be endangered by future deep-sea mining. Within their remote habitats, however, certain snails such as vent limpets can be very common – up to 400,000 individuals were counted on a single square meter! This is possible only because vents provide large amounts of food to their inhabitants-they are flourishing oases of life in the vast deep sea. Scientists found that many snails feed on bacteria growing on the seafloor, and some can even filter food particles from the water. A few are carnivores that prey on other animals, or they consume animals that died. Unlike the mussels we encounter during the dives, snail primarily relying on symbiotic bacteria for nutrition are missing in our area, but occur in the south-west Pacific and Indian Oceans. During our expedition, we will explore different active and inactive areas on the volcano, and are looking forward to what kinds of exotic snails we will be able to collect and study.