▁are ▁located ▁in ▁the ▁ne ct os ome ▁where ▁they ▁can ▁coordinate ▁the ▁sw imming ▁of ▁colon ies . ▁The ▁ne ct op hor es ▁have ▁also ▁been ▁observed ▁in ▁working ▁in ▁conj unction ▁with ▁re product ive ▁structures ▁in ▁order ▁to ▁provide ▁prop ulsion ▁during ▁col ony ▁det achment . ▁B ract s ▁B ract s ▁are ▁zo oid s ▁that ▁are ▁unique ▁to ▁the ▁si phon op hor ae ▁order . ▁They ▁function ▁in ▁protection ▁and ▁maintain ing ▁a ▁neutral ▁bu oy ancy . ▁However , ▁b ract s ▁are ▁not ▁present ▁in ▁all ▁species ▁of ▁si phon oph ore . ▁Gast ro zo oid s ▁Gast ro zo oid s ▁are ▁poly ps ▁that ▁have ▁evol ved ▁a ▁function ▁to ▁assist ▁in ▁the ▁feed ing ▁of ▁si phon op hor es . ▁Pal p ons ▁Pal p ons ▁are ▁modified ▁g astro zo oid s ▁that ▁function ▁in ▁dig estion ▁by ▁reg ulating ▁the ▁circul ation ▁of ▁g astro vas cular ▁flu ids . ▁Gon op hor es ▁Gon op hor es ▁are ▁zo oid s ▁that ▁are ▁involved ▁in ▁the ▁re product ive ▁processes ▁of ▁the ▁si phon op hor es . ▁P neum at op hor es ▁The ▁presence ▁of ▁p neum at op hor es ▁character izes ▁the ▁sub groups ▁C yst on ect ae ▁and ▁Phys on ect ae . ▁They ▁are ▁gas - filled ▁flo ats ▁that ▁are ▁located ▁at ▁the ▁anterior ▁end ▁of ▁the ▁colon ies ▁in ▁these ▁species . ▁They ▁function ▁to ▁help