Answer;
REM sleep
Xander is probably experiencing REM sleep.
Explanation;
-REM sleep is a stage of sleep that is characterized by low muscle tone, rapid eye movements and dreams. It is present in all mammals and has unique physiologic properties that distinguish it from non-REM sleep.
-It is believed that the chemical and electrical activity that regulate this sleep phase originate in the brain stem, and this is most notably characterized by a combination of an abundance of acetylcholine (a neurotransmitter), and the almost complete absence of serotonin, histamine, and norepinephrine.
Cells are so small so the surface area and volume of them can be proportional to each other. This helps with the efficiency of the cell's absorption and waste expulsion processes. Also by the cell's smallness, communication from the nucleus to other organelles is fast and the cell can be regulated while the conditions for diffusion are still ideal.
1. Biogeography
2. The fossil record
3. Embryology
4. Genetics
5. Observable evolution on small timescales
d, planarians avoid light
