You would expect an earthworm to have no exoskeleton because as you see it is very flexible and soft. Organisms with such have body parts that are divided and an earthworm do not have any visible parts on them also having an exoskeleton would not allow an organism to move like an earthworm does.
In secondary succession, the pioneer species are plants that are adapted to exploit disturbances rather than bare rock. They typically include plants such as grasses, birch trees, and fireweed. Organic matter from the pioneer species improves the soil so other trees and plants can move into the area.
The energy pyramid describes decomposers compared to energy lost as heat. Primary producers start at 100% and it decreases to 10% at primary consumers, 1% at secondary, .1% at third level, and .01% at apex.
The biomass pyramid describes the total mass of an organism and as a biomass moves up, the overall mass is losing volume. This means it decreases as it moves from the bottom to the top.
