Earthworms are part of the Phylum Annelida which includes marine worms and leeches. There are no native earthworms in the Hawaiian Islands, but introduced earthworms are now common here. It is not yet known how many species can be found in Hawai'i or when they were introduced.

Earthworms do not have eyes or ears, but are very sensitive to heat , light , and touch. Earthworms burrow down into the cool , moist soil to avoid getting dehydrated. Tiny bristles cover the body of the worm and help it grip the soil as it travels underground. It is not yet known what species of earthworms can be found in Hamakua Marsh. Wetlands birds that are known to eat earthworms are the 'Alae'ula, Koloa and the 'Alae Ke'okeo,