, ▁and ▁their ▁emb ry os ▁do ▁not ▁under go ▁spir al ▁cle av age ▁as ▁in ▁most ▁other ▁proto st om es . ▁An c estr ally , ▁the ▁group ▁exhib ited ▁s cler ot ized ▁teeth ▁within ▁the ▁for eg ut , ▁and ▁a ▁ring ▁of ▁sp ines ▁around ▁the ▁mouth ▁opening , ▁though ▁these ▁features ▁have ▁been ▁second arily ▁lost ▁in ▁certain ▁groups . ▁ ▁Ph y log eny ▁▁ ▁The ▁E cd y so zo a ▁include ▁the ▁following ▁ph y la : ▁Ar th rop oda , ▁O nych op hora , ▁T ard igr ada , ▁Kin or h yn cha , ▁Pri ap ul ida , ▁Lor ic if era , ▁N emat oda , ▁and ▁N emat om or pha . ▁A ▁few ▁other ▁groups , ▁such ▁as ▁the ▁g astro tr ich s , ▁have ▁been ▁considered ▁possible ▁members ▁but ▁lack ▁the ▁main ▁characters ▁of ▁the ▁group , ▁and ▁are ▁now ▁placed ▁elsewhere . ▁The ▁Ar th rop oda , ▁O nych op hora , ▁and ▁T ard igr ada ▁have ▁been ▁grouped ▁together ▁as ▁the ▁Pan arth rop oda ▁because ▁they ▁are ▁distinguished ▁by ▁segment ed ▁body ▁plans . ▁D unn ▁et ▁al . ▁in ▁ 2 0 0 8 ▁suggested ▁that ▁the ▁tard igr ada ▁could ▁be ▁grouped ▁along ▁with ▁the ▁n emat odes , ▁leaving ▁O nych op hora ▁as ▁the ▁sister ▁group ▁to ▁the ▁ar th rop ods . ▁The ▁non - pan arth rop od ▁members ▁of ▁E cd