I do not believe mermaids exist because of the biological incompatibility of the two systems. There would firstly be duplication of organs from the human-fish combination. Secondly, the skeletal structures would clash and create more incompatibilities. Thirdly, the structure of a lung would not work. Gills would not be able to work with the body structures of a mermaid.
Also, a mermaid would need to have fragments of fish DNA. DNA has very strong barriers across species. It is difficult for anything larger than a bacteria to take in any DNA from another species. The fish DNA and making it apply to only the legs would be impractical. If a human was to evolve to live in water, it would not evolve into a mermaid.
It's often futile to try to convince people that they should adopt a particular political position, but if you try, make sure to appeal to logic. Try to eliminate as much emotion from your argument as possible.
Solar eclipses result from the Moon blocking the Sun relative to the Earth; thus Earth, Moon and Sun all lie on a line. Lunar eclipses work the same way in a different order: Moon, Earth and Sun all on a line.
