Some vent animals, like limpets, clams, and mussels feed directly on bacteria. Other animals, such as octopi, prey on those that eat bacteria. Vent crabs act as both predator and scavenger. Some of the most successful vent animals, tube worms and giant clams, form symbiotic relationships with chemosynthetic bacteria . The bacteria live within the animals' tissues and provide a built-in food supply.
Tube worms have no mouth, gut, or anus.
Nutrients are absorbed directly into tissues. Two species of tube worms inhabit hydrothermal vent s. The smaller of the two, Tevnia jerichonana , which grow at a rate of 30 centimeters per year, are among the first animals to colonize and dominate the vent ecosystem . Over 300 new species of animals have been discovered at vents. Many are found nowhere else on earth, and could not exist outside the conditions at vents.