▁green ish ▁h ue ▁to ▁their ▁skin . ▁A ▁V ul can ' s ▁on - screen ▁blood ▁is ▁green ▁due ▁to ▁co pper - based ▁hem oc yan in . ▁V ul c ans ▁are ▁said ▁to ▁possess ▁an ▁inner ▁e y el id , ▁or ▁n ict it ating ▁memb rane , ▁which ▁protect s ▁their ▁vision ▁from ▁bright ▁light . ▁In ▁addition , ▁their ▁heart ▁is ▁located ▁on ▁the ▁right ▁side ▁of ▁the ▁tor so , ▁between ▁the ▁rib s ▁and ▁pel vis ; ▁as ▁Dr . ▁Mc Co y ▁once ▁says ▁about ▁Spo ck : ▁" He ▁is ▁luck y ▁that ▁his ▁heart ▁is ▁where ▁his ▁li ver ▁should ▁be , ▁or ▁he ' d ▁be ▁dead !" ▁ ▁Diet ▁V ul c ans ▁are ▁veget ari ans ▁by ▁choice ▁and ▁were ▁om n iv ores ▁in ▁ages ▁past . ▁It ▁is ▁a ▁V ul can ▁custom ▁for ▁guests ▁in ▁the ▁home ▁to ▁prepare ▁me als ▁for ▁their ▁hosts . ▁ ▁V ul c ans ▁are ▁said ▁to ▁not ▁drink ▁alco hol , ▁though ▁they ▁are ▁often ▁dep icted ▁as ▁doing ▁so . ▁ ▁In ▁an ▁episode ▁of ▁Star ▁Tre k : ▁Deep ▁Space ▁N ine , ▁Qu ark ▁all udes ▁to ▁V ul c ans ▁becoming ▁in eb ri ated ▁by ▁ing est ing ▁ch oc olate . ▁▁ ▁An ▁episode ▁of ▁Star ▁Tre k ▁Vo y ager ▁mentions ▁that ▁V ul can ▁coffee ▁is ▁poison ous ▁to ▁humans . ▁ ▁M ating ▁drive ▁ ▁Every ▁seven ▁years