The FEW includes the term in the volume of 'inconnus' though a derivation from TANTUS 13/i,85b and PES 8,293a seems likely. DMLBS lists a similar compound multipes (1855a) with 'shrimp' being one sense. The compound many-foot is attested from 1600 in English (OED many a., pron. and n.). The OED also notes the Latin form tautopodia (OED tautopody n.: a prosody term for indicating a single metrical foot) to which the form could be related.