The mud creature that lives without oxygen

From Zoologger - 07 April 2010 - New Scientist

Assigned the genus Spinoloricus, the animal is less than a millimetre long. The other two new loriciferan species Danovaro found resemble water fleas, one given the genus name Rugiloricus and the other Pliciloricus. Some specimens contained an unfertilised egg.

The beasts live in conditions that would kill every other known animal. As well as lacking oxygen, the sediments are choked with salt and swamped with hydrogen sulphide gas.

None of the animals has mitochondria, the "power stations" that generate energy from oxygen in the cells of all oxygen-using organisms. Instead, they rely on structures called hydrogenosomes, which generate energy from molecules other than oxygen, including hydrogen sulphide.

Hydrogenosomes are well known in protozoa that live in oxygen-free environments, but the three new creatures are the first animals to be found that rely completely on them. One possibility is that the loriciferans acquired the hydrogenosomes from protozoa.