Maina, J.N., Maloiy, G.M.O. and Wood, C.M. 1998. Respiratory stratagems, mechanisms, and Mnorphology of the "lung" of a tropical swamp worm, Alma emini Mich. (Oligochaeta: Glossoscolecidae): A transmission and scanning electron microscope study, with field and laboratory observations.Journal of Zoology 245:483-495.
The African swamp worm, Alma emini, has evolved a unique and innovative respiratory strategy that allows it to occupy a seemingly uninhabitable habitat. What is this remarkable adaptation and how does it allow the worm to maintain aerobic metabolism in a virtually anoxic environment?
The swamps that Alma resides in are devoid of oxygen, highly reducing, and saturated by poisonous gases such as hydrogen sulfide and methane. Alma can survive in such a hostile place by having a respiratory structure analogous to the vertebrate lung. On the posterodorsal part of the body, Alma possesses a sort-of makeshift respiratory structure, which it mobilizes in contact with the air. This "lung", unique to the swamp worms, traps air and/or water so that the worm can breathe in the anoxic detritus matter of the African swamps.
The morphology of the "lung" was examined by electron microscopy and was characterized by a high degree of vascularization and a thick coat of mucus, not unlike human lungs. When the worm is not respiring the temporary lung is dismantled and exists as a tiny groove on its dorsal surface. Upon contact with the surface of the soil, the worm unfolds the "lung" and gas exchange occurs.
Alma can subsist in an anoxic habitat and still retain a capacity for aerobic metabolism by periodically surfacing and extracting oxygen directly from the atmosphere using a zipper-like "lung". This quintessential feature demonstrates how Alma is able to thrive in the most severe of habitats.
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