Flatworms have no need for circulatory and respiratory systems because they are able to actively diffuse oxygen through their skin and their body layout is such that they do not need to transport oxygen in order for it to get to their cells.
There was Colorado and Washington that legalized it, but the first is Colorado's prop 64 made legal for anyone over the age of 21 to possess it.
Answer:
decomposing and recycling organic materials in it's habitat.
When studying a complex biological phenomenon, it is required to look at the workings of the various systems associated with it. The research is a top-down approach of getting down to the very detail of the cells and molecules taking part in it. Example, a person finds it difficult to digest milk and vomits it on ingestion. As we go a level down, we identify the systems getting affected by the milk. Then, further down, the cells that take in digesting the milk are identified. The enzymes that break down the substances in the milk are identified. The gene regulation of this enzyme (lactase) is studied to check its regulation. This work of doing a top-down approach to find the signalling pathway within the cells to identify the problem with the working of lactase to digest milk, is a necessary approach.
