ilt . ▁Ant rob ia ▁cul ver i ▁is ▁using ▁a ▁solid ▁rock ▁bottom , ▁and ▁the ▁species ▁is ▁usually ▁observed ▁on ▁the ▁unders ur face ▁of ▁rocks ▁and ▁gra vel ▁of ▁various ▁sizes . ▁ ▁Observ ations ▁between ▁March ▁and ▁August ▁ 2 0 0 1 ▁suggest ▁that ▁Ant rob ia ▁cul ver i ▁is ▁now ▁restricted ▁to ▁ 2 3 ▁m ▁of ▁available ▁stream ▁habitat ▁or ▁approximately ▁ 5 ▁percent ▁of ▁the ▁ 4 5 7 ▁meters ▁of ▁accessible ▁suitable ▁habitat . ▁ ▁Species ▁such ▁as ▁the ▁T umb ling ▁Creek ▁c aves n ail , ▁which ▁spend ▁all ▁of ▁their ▁life ▁cycle ▁in ▁sub ter rane an ▁waters , ▁are ▁highly ▁vulner able ▁to ▁changes ▁in ▁the ▁quality ▁and ▁quantity ▁of ▁that ▁water . ▁ ▁Fe eding ▁hab its ▁ ▁Although ▁little ▁is ▁known ▁regarding ▁the ▁bi ology ▁of ▁this ▁c aves n ail , ▁it ▁is ▁believed ▁that ▁the ▁species ▁fe eds ▁on ▁aqu atic ▁micro fa una ▁( i . e ., ▁the ▁micro scop ic , ▁b acter ial ▁film ▁or ▁“ bio film " ▁which ▁does ▁appear ▁to ▁be ▁ing ested ▁by ▁the ▁c aves n ail ). ▁Because ▁T umb ling ▁Creek ▁c aves n ails ▁are ▁usually ▁concentr ated ▁in ▁those ▁sections ▁of ▁T umb ling ▁Creek ▁C ave ▁which ▁are ▁adjacent ▁to ▁large ▁depos its ▁of ▁bat ▁gu ano , ▁it ▁has ▁been ▁suggested ▁that ▁Ant rob ia ▁cul ver i ▁is ▁indirect ly ▁dependent ▁upon ▁these ▁depos its ▁for ▁food . ▁