Preview of the book:

Treasures from the Sea for Medicine

Urinary tract pain due to the presence of a stone(s) can be excruciating. Even the strongest pain killers may not relieve this pain. Fortunately, the condition is not common in humans; but, a blob-like animal, the sea squirt (Figure 12) regularly accumulates calcium oxalate kidney stones, the type most common to humans.

Unlike humans, the sea squirt kidney is really a renal sac with no outlet, thus there is no chance of passing these stones. Nature instead has provided a mechanism whereby the calcium oxalate crystals are processed and recycled. Microorganisms seem to assist in the metabolism of the crystal concretions. Further, the renal-sac fluid contains more non-crystallized, i.e., dissolved, oxalate than human kidneys. There seems to be a chemical factor in the renal-sac fluid that is twenty times more powerful at inhibiting crystallization than anything in human urine. The isolation of this substance may help physicians prevent kidney stones. Mary Beth Saffo, of Arizona State University in west Phoenix, points out that a kidney stone researcher would never have looked inside a sea squirt.

Clams and other mollusks have many urinary tracts, and these are almost universally filled with stones. The most common inorganic constituent of their stones is calcium phosphate, also common in human stones. Perhaps mollusks, along with sea squirts, could be useful in studying urinary tract stone formation and prevention.