Must every number of a species to reproduce in other for the survive?

No, every number of a species does not need to reproduce in order for the species to survive. In fact, some species may have populations that are very small, yet they are still able to survive and reproduce successfully. This is because reproduction is not the only factor that affects a species' survival. Other factors, such as the availability of food and water, the presence of predators, and the environment in which the species lives, also play a role in determining whether or not a species will survive.

In some cases, a species may be able to survive with a very small population size because it has a high reproductive rate. This means that even though there are only a few individuals in the population, they are able to produce enough offspring to sustain the population. In other cases, a species may be able to survive with a small population size because it is able to adapt to its environment. This means that the individuals in the population are able to change in ways that make them better suited to survive in their environment.

Ultimately, the number of individuals that a species needs to reproduce in order to survive will vary depending on the specific species and its environment. However, it is important to note that every number of a species does not need to reproduce in order for the species to survive.