It may seem like a moment in a science fiction movie. In a fierce battle, a creature loses an arm but, then, grows another one to take its place. However, this is not science fiction. It is scientific fact. Some fish and amphibians, such as salamanders, can regrow lost limbs and organs. As mammals evolved they lost the ability to regrow, or regenerate, parts of their body. However, experiments show that it may be possible to regain that ability. Tropical freshwater zebrafish are popular pets. They are also popular as lab animals. Their embryos are clear, or translucent. They can regrow damaged fins, skin and hearts. Zebrafish are also genetically similar to humans. In 2013, the website Sci-News reported that researchers had found that 70 per cent of “protein-coding human genes” are related to genes found in the zebrafish. The report also said that researchers at the Wellcome Trust Sanger Institute in Britain also found that 84 per cent of genes known to be connected to human disease have a zebrafish counterpart. These researchers published their findings in the scientific journal Nature.