Notes on an American Cave Flatworm, Sphalloplana Percaeca (Packard)

Observations on the biology of cave planarians of the United States

“…Because most caves have a very high relative humidity, cave planarians can probably live out of water for some time. Buchanan (1936) noted in his behavioral studies on S. percoeca that «when agitated the animals showed a tendency to leave the water and creep about above the water level. «I have noticed the same tendency, and pometimes the worms leave the water without being agitated.…”

“…Buchanan (1936) suggested that it is "probable that the flatworms are located on the nether side of rocks because they are deposited there by water currents and because the same currents deposit under the rocks the materials which furnish their subsistence». I have never observed their showing any preference for the nether sides of rocks, nor is there any indication the worms are often carried downstream by currents.…”

“…Those found in relatively warm water are usually tolerant to cold temperatures as well, but worms normally living in cold water are seldom tolerant to warm temperatures. Buchanan (1936) kept two S. percoeca at 24°C for 3 hours without injurious effect. Although I did not perform extensive experiments, I found that some species (especially stream dwellers such as S. priceiJ cannot live very long at temperatures much above 14°C.…”

“…Both Buchanan (1936) and McRitchie (1959) noted that a brief exposure to strong sunlight resulted in writhing and eventually in death and disintegration of species of Sphalloplana.…”

“…13,18,24,25,26,27). Hyman (1937) suggested that the adhesive organ of Sphalloplana is probably used in food capture, but most investigators who have examined live cave planarians have had no success in feeding them (e.g., Buchanan, 1936;Mitchell, 1968). As mentioned, most of the time I fed my cave planarian cultures on dried blood because of convenience.…”