Yes, DECAPOD is a Scrabble word!

Letter values in Scrabble US: D 2, E 1, C 3, A 1, P 3, O 1, D 2.

Is it a valid word?

DECAPOD is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

crustaceans characteristically having five pairs of locomotor appendages each joined to a segment of the thorax
cephalopods having eight short tentacles plus two long ones

Also: decapod crustacean.