Annelida Phylum
The earthworm’s integument is in control of many life processes. First, it is responsible for letting oxygen into the blood. This is done by absorbing oxygen from its surroundings and allowing it diffuse into the blood that passes through the skin layer. The earthworm’s outer layer is always moist because of a special mucous which come from glands in its skin. This mucous is important because it enables microbes to permeate the skin, as well as lining the tunnels it creates and keeping them more solid, which allows for better aeration of the soil. The skin is also sensitive to light, touch, and chemicals and allows the worm to better understand its surroundings. The integumentary system of the earthworm is also essential in allowing it to move, because of a sac in its skin called the setigerous sac which controls the setae. These are bristles which stick out of the worm and allow it to anchor part of its body while it contracts or stretches the other, giving it the ability to move.
The picture above is that of a leech, another member of the Annelida phylum with a similar integumentary system as the earthworm. These skins have a cellular epidermis that secretes a thickened, non-living transparent cuticle; cilia present in many forms. Setae is absent in this specific species but is often present within this phylum.
These are rag worms, another exquisite member of the Annelida Phylum. This species contains the same characteristics as worms and leeches, the reason that it is placed in the Annelida phylum. These are simple sponge organisms as you can see, the external defenses or skin are similar and have the same purposes.