▁ 7 5   mm ▁long . ▁This ▁species ▁has ▁ro str um ▁be ars ▁ 7 - 9 ▁teeth ▁d ors ally ▁and ▁ 5 - 8 ▁vent r ally . ▁ ▁Ju ven ile ▁and ▁adult ▁pra wn s ▁are ▁om n iv orous ▁and ▁feed ▁on ▁alg ae , ▁pl ank ton ic ▁organ isms , ▁small ▁mus cle ▁pieces ▁of ▁their ▁own ▁kind ▁or ▁fish . ▁Post ▁lar va e ▁pra wn s ▁feed ▁on ▁pure ▁animal ▁di et ▁than ▁on ▁mixed ▁di et ▁of ▁alg ae ▁and ▁nau p li i . ▁ ▁Be havior ▁Pra wn s ▁of ▁different ▁sizes ▁do ▁not ▁attack ▁each ▁other . ▁When ▁pra wn s ▁die ▁or ▁become ▁weak , ▁others ▁may ▁attack ▁and ▁make ▁them ▁into ▁their ▁me al . ▁ ▁References ▁ ▁Category : P ala em ono idea ▁Category : F resh water ▁cr ust ace ans ▁of ▁Asia ▁Category : Cr ust ace ans ▁described ▁in ▁ 1 8 3 7 <0x0A> </s> ▁A que ous ▁ge och em istry ▁studies ▁the ▁role ▁of ▁various ▁elements ▁in ▁waters h eds , ▁including ▁co pper , ▁sul fur , ▁and ▁mer cur y . ▁Research ers ▁in ▁this ▁field ▁also ▁study ▁how ▁element al ▁flux es ▁are ▁ex changed ▁through ▁interactions ▁between ▁the ▁atmosphere , ▁the ▁earth ▁or ▁soil ▁( ter rest rial ▁interactions ) ▁and ▁bodies ▁of ▁water ▁( aqu atic ▁interactions ). ▁ ▁Work ▁in ▁the ▁field ▁of ▁a que ous ▁ge och em istry ▁has ▁also