Some sponges produce toxins that harm other sponges. what is the best explanation for why they do this?

Sponges are the members of the phylum Porifera. They have cellular level of body organization and they are sedentary. The space, food and other resources are limited. This leads to lot of competition for space among the sponges. Some of the sponges produce toxins to stop other sponges from settling down nearby or very close to another one. Toxins secreted by sponges provide a competitive advantage.

Sponges are known to produce and release certain toxins. The release of the toxins serve many purposes, such as the defending themselves against the pathogens and other parasites. But these chemicals are also known to harm other sponges, which serves another purpose of their production. The space in the coral reefs is quite limited, and hence, to avoid the settling of the other sponges too close to themselves, and to eliminate competition, the sponges release these toxins.

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.