The word tetrapods 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: 13
Highest Scoring Words With Friends™ Play In The Letters tetrapods
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Seven Letter Word Alert: (25 words)
adopter, departs, deports, detorts, dotters, patters, petards, potters, protest, readopt, retoast, roasted, rotated, rotates, seaport, spatted, spatter, sported, spotted, spotter, started, tapster, teapots, toasted, toaster