Lately a National Geographic expedition to the bottom of the 6 mile deep Mariana Trench was said by the media to have found to have discovered the world’s largest xenophyophores 6 miles down (they can get nearly a foot across but shaped like a plate – see Stannophyllum venosum). But these are not quite unicellular organisms – indeed they are more interesting – and they have had their DNA sequenced (a major accomplishment given the large numbers of bacteria and other micro-organisms living around them).
Xenophyophores were discovered nearly a hundred years ago (they are abundant, carpeting the ocean floor in some places), but each year we learn a bit more about these creatures that come in different shapes and sizes and can live in the harshest conditions. They make do by eating sediment, even if it contains heavy metals like uranium. “Xenophyophore” means “bearer of foreign objects”, and refers to the external test of the organism, which it constructs by cementing together objects it collects from the sediment around it – sand grains, for instance, or shells of other organisms – using a polysaccharide cement – a secretion of a kind of organic cement with which to build their bodies.
Xenophyophores are not quite unicellular but have instead a coenocytic or hyphal organization, with numerous nuclei scattered throughout long branching cytoplasmic tubes. Like early humans who used their feces for glue for the huts, the xenos also sequester their fecal pellets so they may be used in the building of their skeleton. The science folks determine different species by the way they arrange the foreign particles in the skeleton (called the “test” in some write-ups) and the proportion of foreign particles to cement or fecal pellets.
So if you wondered if humans invented the idea of holding the walls of our huts together with dung, nope – we got the idea long before we became humans. But we have improved on the idea, as bush warbler droppings are today a traditional human skincare product in the Far East. No – really – they are so used 🙂 – I am so proud of resisting the use of the standard phrasing “No S – – t” in this sentence 🙂