The word heterotrophs is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 19
Highest Scoring Words With Friends™ Plays In The Letters heterotrophs
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Seven Letter Word Alert: (37 words)
heptose, heteros, hotpots, hotshot, hotspot, poorest, porters, pothers, potshot, potters, presort, pretest, protest, reports, reposer, reroots, reshoot, reshore, restore, retorts, rhetors, rooster, rooters, rosette, rotters, shooter, shorter, soother, spotter, stooper, strophe, tethers, thereto, tooters, torpors, treetop, trooper