Entry+2

Some of the environmental pressures that could be driving natural selection in my eco-zone are the separation of the tide-pool from the ocean, the close proximity of the crabs and Blennies, and the growth rate of the algae. The distance between the tide-pool and the ocean determines how likely it is that the Blennies will receive fresh ocean water for their tide-pool. If the tide-pool were much farther inland, it would become stagnant and eventually evaporate, killing all remaining Blennys and algae. As it is however, the tide-pool is located within a yard of the shoreline, and about two yards from the stones where the crabs reside. Blennies who are physically capable may be able to wriggle to another tide-pool if the original tide-pool should evaporate. Those who do not have the strength, persay the runt of the litter, may perish, and the runty gene will not be passed on. This neighboring mass of stones harbors at least three different crabs that I was able to glimpse, and the empty, dried up tide-pools in the vicinity also house other crabs, one of which I was able to photograph. The short distance between the crabs and the Blennies infers that the crabs do not have to travel very far to feed. However, I suspect that there is some competition or cannibalism amongst the crabs; for there was an empty limb carapace segment lying within the stones. Perhaps weak, old, or incapacitated crabs are eaten by the other crabs. Or perhaps it is their corpses that are eaten. Whatever the case, those crabs that are most suited for fishing for Blennies in tide-pools will acquire the most food and chances for survival. Crabs who are not well-suited, or are too large to hunt for Blennies in the crevices in the rocks must find another food source or kick the bucket.

The growth rate of the algae determines how much food supply there is for the Blennies, and how long that population of algae will survive. The more algae, the more excrement, and thereby, the more new algae. If the amount of algae mass is not large enough, the algae may be totally consumed by the Blennies, and the Blennies will starve. A limited supply of algae will be largely consumed by the most powerful and speediest Blennies, thereby refining the population to the fittest Blennies in the tide-pool. A deficiency in algae amount may also cause the algae to evolve new adaptations in order to survive in its environment. Speciation may occur for the benefit of the algae.