Spores of fungus, <em>Candida albicans</em> b/w Spores of fungus, <em>Candida albicans</em>

Spores of fungus, Candida albicans

The long strands are the tubular filaments (hyphae) that have developed from the fungal spores. Yeast cells (rounded, yellow) are budding from the ends of the hyphae (red). Candida albicans causes the infection known as candidiasis which affects the moist mucous membranes of the body, such as skin folds, mouth, respiratory tract and vagina. Oral and vaginal conditions are known as thrush.

Archaea

Archaea can be spherical, rod, spiral, lobed, rectangular or irregular in shape. An unusual flat, square-shaped species that lives in salty pools has also been discovered. Some exist as single cells, others form filaments or clusters. Until the 1970s this group of microbes was classified as bacteria.

  • <em>Sulfolobus</em>

    Sulfolobus

    Sulfolobus is an extremophile that is found in hot springs and thrives in acidic and sulphur-rich environments.

    © Eye Of Science / Science Photo Library

  • <em>Methanosarcina rumen</em>

    Methanosarcina rumen (green with red cell walls).

    Methanosarcina rumen is anaerobic, and is found in places with little or no oxygen. It is a methane- producing organism that digests decaying organic matter. It is found in the rumen of a group of animals called ruminants such as cattle and sheep.

    © Eye Of Science / Science Photo Library

  • <em>Staphylothermus marinus</em>

    Staphylothermus marinus

    Staphylothermus marinus is an extremophile found in deep ocean hydrothermal vents, thriving on volcanic sulphur and surviving in water temperatures of up to 98°C.

    © Wolfgang Baumeister / Science Photo Library

  • <em>Halococcus salifodinae</em>

    Halococcus salifodinae

    Halococcus salifodinae is found in water with high concentrations of salt. These high salt concentrations would be deadly to most other forms of life, and so H. salifodinae is also known as an extremophile.

    © Eye Of Science / Science Photo Library

  • <em>Methanococcoides burtonii</em>

    Methanococcoides burtonii

    Methanococcoides burtonii is an extremophile and was discovered in 1992 in Ace Lake, Antarctica, and can survive in temperatures as low as -2.5 °C.

    © Dr Keith Wheeler / Science Photo Library

Many archaea have been found living in extreme environments, for example at high pressures, salt concentrations or temperatures, and have been nicknamed extremophiles. Their cell wall differs in structure from that of bacteria and is thought to be more stable in extreme conditions, helping to explain why some archaea can live in many of the most hostile environments on Earth.

Examples of archaea habitats are boiling hot springs and geysers such as those found in Yellow Stone Park, USA and ice such as the Artic and Antarctic oceans which remain frozen for most of the year.