Did the first organisms have one or more cells?

Answer 1

Yes, there are many organisms that are composed of a single cell.

Answer 2

Recall that the first organisms were made up of single cells. Most organisms living today are single-celled. However, more and more species have developed more and more complex cells and structures over time.

Answer 3

There is no way to answer your question until we create a time machine. There were no people there, so no way to tell which was first. It is likely that it was a simple bacteria, but we do not know WHICH bacteria.

Answer 4

Likely, they were some sort of colony-organism, like Volvox today. Such organisms will exist as single cells for most of the time, but form colonies, aggregates of many thousands of cells, when under stress, for instance from predation or lack of food.

Answer 5

Yes, there are many organisms that are composed of a single cell.

Answer 6

Sponges, jellyfish, worms.