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Is there a living thing that does not move?
Question Date: 2013-08-18
Answer 1:

That´s an interesting question. There are lots of organisms that are sessile--- meaning that they don´t move-at least after they´ve reached a certain point in their life. For example, lots of plants release seeds that move by wind, water, or by catching a ride with animals (for example the fluffy seeds of dandelions or the bristly seeds of thistle), but once they land in a spot where they can grow, they put out roots and don´t move for the rest of their lives (they too might release seeds that can move away from the parent plant though). Similarly, many marine organisms, like oysters and sponges (to name a few) move through the water by drifting early in their life (this is called a `pelagic stage´) but once they settle in an area, like a rocky sea surface, they will attach for life. That´s how features like oyster beds and coral reefs form!

Answer 2:

There are some living organisms that don't move. Two examples are adult barnacles and coral!


Answer 3:

In the field of biology, we have defined a set of requirements that characterize what a living thing is. One of the requirements is that living things respond to stimuli, and usually this means motion. Essentially all living things move, even if they move very slowly (like plants growing toward the sun), or rarely (like coral, which only moves when its survival is threatened by danger or lack of food), or only during one phase of their lifetime (like female scale insects, which crawl as juveniles, but become immobile as adults). There may be exceptions out there because Earth is a wild place and organisms exist that defy our efforts to categorize and organize them, but it's safe to say that most all living things move.

Answer 4:

Good question! For an organism to move, it must have specialized parts designed to give it motion. For example, in small bacteria, there might be flagella (microscopic tails) or hairs that can be triggered to flex or rotate in order to produce motion. In larger animals like humans, specialized tissue called muscle can contract and expand, permitting rotation and movement at a macroscopic level. So by these definitions, there could be many things that do not move. A great majority of plants, for instance, lack specialized tissue to move. But plants are okay with that, because while most organisms need to move to find and collect food, a plant’s big “food” source is the Sun, and it’s always in the sky so plants don’t need to move!

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