Largest organisms photosynthetic unicellular and multicellular protists that are related to land plants. The thallus of the unicellular mermaid's wineglass, "Acetabularia", can grow to several inches (perhaps 0.1 to 0.2 m) in length. The fronds of the similarly unicellular, and invasive "Caulerpa taxifolia" can grow up to a foot (0.3 m) long. A member of the order Cetacea, the blue whale ("Balaenoptera musculus"), is thought to be the largest animal ever to have lived. The maximum recorded weight was 190 metric tonnes for a specimen measuring , whereas longer ones, up to , have been recorded but not weighed. The African bush
The Long Earth (series) greater details. All share one similarity: on none are there, or have there ever been, "Homo sapiens" - although the same cannot be said for earlier hominid species, especially "Homo habilis". The books explore the theme of how humanity might develop when freed from resource constraints: one example Pratchett has cited is that wars result from lack of land, and he was curious as to what would happen if there was no shortage of land or other resources. The Long Earth (series) The Long Earth is a collaborative science fiction work by British authors Terry Pratchett and Stephen Baxter. Both