9 3 9 ▁establish ments ▁in ▁U g anda <0x0A> </s> ▁The ▁G ec arc in idae , ▁the ▁land ▁c rab s , ▁are ▁a ▁family ▁of ▁true ▁c rab s ▁that ▁are ▁adapted ▁for ▁terrest rial ▁existence . ▁Similar ▁to ▁all ▁other ▁c rab s , ▁land ▁c rab s ▁possess ▁a ▁series ▁of ▁g ills . ▁In ▁addition , ▁the ▁part ▁of ▁the ▁car ap ace ▁covering ▁the ▁g ills ▁is ▁infl ated ▁and ▁equ ipped ▁with ▁blood ▁vessels . ▁These ▁org ans ▁extract ▁o xygen ▁from ▁the ▁air , ▁analog ous ▁ ▁to ▁the ▁verte br ate ▁l ungs . ▁Ad ult ▁land ▁c rab s ▁are ▁terrest rial , ▁but ▁visit ▁the ▁sea ▁period ically , ▁where ▁they ▁bre ed ▁and ▁their ▁lar va e ▁develop . ▁Land ▁c rab s ▁are ▁tropical ▁om n iv ores ▁which ▁sometimes ▁cause ▁considerable ▁damage ▁to ▁cro ps . ▁Most ▁land ▁c rab s ▁have ▁one ▁of ▁their ▁cla ws ▁larger ▁than ▁the ▁other . ▁ ▁The ▁family ▁contains ▁these ▁gener a : ▁ ▁Card is oma ▁ ▁Disc op lax ▁ ▁Ep ig ra ps us ▁ ▁G ec arc inus ▁ ▁G ec ar co idea ▁ ▁Joh ng arth ia ▁ ▁See ▁also ▁Ses arm idae , ▁another ▁family ▁of ▁terrest rial ▁c rab s ▁Co en ob it idae , ▁terrest rial ▁herm it ▁c rab s ▁ ▁References ▁ ▁Enc arta ▁Reference ▁Library ▁Prem ium ▁ 2 0 0 5 ▁DVD . ▁ ▁Category : G