Explore the Deep Sea
Life in the Deep
Tiny but very important for life around hydrothermal vents
Microbes at the base of the deep-sea food chain
Microbes are single-celled organisms. But though they're small, they are hugely important in the deep ocean, where they are found in countless billions. Thanks to microbes, we find a teeming abundance of animals around many volcanoes and vents on the seafloor. Microbes provide food for deep-sea animals in two ways:
- Some microbes are eaten. Certain types of animal, such as deep-sea shrimp and snails, graze on microbes living free in the water or on rocks.
- Some sorts of microbe live inside animals, such as tubeworms and mussels, and manufacture food for them. Certain kinds of animal, such as tubeworms, derive all their food from these symbiotic bacteria ("symbiotic" means "living together"). They provide the microbes with a place to live and the chemical ingredients to make sugars and other nutrients. In return, the microbes provide the animals with much of the food they make.
Two main kinds of microbe live in the deep sea: bacteria and archaea.
- Bacteria are found in huge numbers all over the Earth—inside your gut, on the highest mountain tops, at the bottom of the sea. While some types of bacteria can cause disease in humans, most kinds don't cause disease, and many are positively beneficial to us.
- Archaea resemble bacteria in shape and size so closely that they used to be classed as bacteria. But detailed study of their genetics and chemical makeup has revealed that they are only very distantly related to bacteria. Like bacteria, they are found in an astonishing range of places—even inside some rocks hundreds of feet deep (where they are carried by fluids trickling through tiny fissures).
» More about the discovery of an acid-loving deep sea member of the Archaea
Amazing heat resistance
Certain species of microbe found around deep-ocean volcanoes and vents have evolved the ability to withstand temperatures that would kill humans and most other organisms. Around deep-sea vents, certain microbes can grow at temperatures of up to 115°C (240°F). Many scientists think that some day we will discover microbes that can thrive in temperatures up to 145°C (295°F).
Some microbes manufacture their own food
Microbes can be classed into two main groups depending on their food source.
- The first group (heterotrophs, or "eaters of other things") "eat" by breaking down organic compounds found in the environment around them (e.g. detritus in the soil).
- The second group (autotrophs, or "self feeders") make their own food. They extract carbon from carbon dioxide in the environment around them, and use it to build more complex, organic molecules like sugars—which they can feed on. Some species (the photoautotrophs) get the energy to do this from sunlight (by photosynthesis). Other microbe species (the chemoautotrophs) get energy from breaking down chemicals in the environment around them (by chemosynthesis). There is no light in the deep sea, but certain chemoautotrophic microbes obtain energy by oxidising chemicals found in vent fluids…more about hydrothermal vents.