The phylum of Platyhemlinthes or better known as the flat worms are a very simple type of animal. What a flat worm is most known for is its method of digesting food. Actually, it doesn't digest food at all. Instead it diffuses it's food into it's body. That is why a flat worm is FLAT because in order for the flat worm to transfer it's food throughout its body, the cells must be close to the body. This is why throughout its evolutionary form the Platyhelminthes has retained a flat shape. Larger flat worms rely on their guts (not a gut feeling) in order to transfer food throughout the entire body. An example of a flat worm is the parasitic Fluke or the Planarian. My favorite flat worm is the tapeworm which literally digests your food for you.
Platyhelminthes do not have a skeletal system. Literally, the flat worm is entirely supported by cells. The cells are connected through connected tissues and the collagen fibers found in these cells act as a type of skeleton. These fibers help support the flat worm, just enough so that gravity doesn't crush it completely.
It is hard to trace the evolutionary trail left behind by flat worms because there is practically no fossil record of any flat worms. There have been only a few cases that have shown fossils, but there has only been baby flat worm fossils found. Sadly, there is no definite theory on how the flat worm has evolved into what it is today.
Platyhelminthes do not have a skeletal system. Literally, the flat worm is entirely supported by cells. The cells are connected through connected tissues and the collagen fibers found in these cells act as a type of skeleton. These fibers help support the flat worm, just enough so that gravity doesn't crush it completely.
It is hard to trace the evolutionary trail left behind by flat worms because there is practically no fossil record of any flat worms. There have been only a few cases that have shown fossils, but there has only been baby flat worm fossils found. Sadly, there is no definite theory on how the flat worm has evolved into what it is today.