They have a cell membrane, they contain cytoplasm and can replicate themselves through the manner of mitosis.
The first invertebrates to show both segmentation and a complete digestive system belong to the phylum Annelida that includes earthworms, leech, sandworms, etc.
These segmented worms have complete digestive system which is also known as tube-within a tube. These can be found in freshwater, marine water or can even be terrestrial.
In scientific equations<span>, </span>photosynthesis<span> takes carbon dioxide from the air, water and sunlight to create sugar. After this happens, oxygen is released back into the air. Cellular </span>respiration<span> takes these same sugars and combines them with oxygen to release the energy as ATP.</span>