It is not required to be an insect or even an invertebrate for something to be considered a worm.
Examples include the earthworm, though it is often called a segmented worm because of the segments along its body. These worms are still very close relatives of ours and other species in our form, in that they share many similar structures such as:
- An unsegmented head using bristles, paired antennae and multiple sensory organs.
- Roughly the same body structure including a nerve cord with ganglia, three main regions (head/thorax/abdomen), and seven sets of body appendages out from there.
- The ability to regenerate lost body parts.
- coelom or fluid filled space between the gut and the outer body wall.
- The presence of an outer skin which can be shed or broken to allow growth.
There are many examples though, including the common earthworms that are very closely related to us in terms of genetics, structure ,and behavior. This is clearly evident due to their regeneration abilities, segmented bodies similar to ours, multiple sensory organs, and the presence of a nerve cord with ganglia.
While it is not required to be an invertebrate or even an insect for something to be considered a worm, it is still interesting that worms share so many similarities with other organisms such as humans considering how much they can differ. Oh yeah, and they’re gross.
