ore ▁species ▁was ▁slow ▁in ▁the ▁ 1 8 th ▁century , ▁as ▁only ▁four ▁additional ▁species ▁were ▁found . ▁During ▁the ▁ 1 9 th ▁century , ▁ 5 6 ▁new ▁species ▁were ▁observed ▁due ▁to ▁research ▁voy ages ▁conducted ▁by ▁European ▁powers . ▁The ▁majority ▁of ▁new ▁species ▁found ▁during ▁this ▁time ▁period ▁were ▁collected ▁in ▁coast al , ▁surface ▁waters . ▁During ▁the ▁HMS ▁Ch allen ger ▁expedition , ▁various ▁species ▁of ▁si phon op hor es ▁were ▁collected . ▁Ernst ▁H ae ck el ▁attempted ▁to ▁conduct ▁a ▁write ▁up ▁of ▁all ▁of ▁the ▁species ▁of ▁si phon op hor es ▁collected ▁on ▁this ▁expedition . ▁He ▁introduced ▁ 4 6 ▁" new ▁species "; ▁however , ▁his ▁work ▁was ▁heavily ▁crit iqu ed ▁because ▁some ▁of ▁the ▁species ▁that ▁he ▁identified ▁were ▁eventually ▁found ▁not ▁to ▁be ▁si phon op hor es . ▁Non eth eless , ▁some ▁of ▁his ▁descri ptions ▁and ▁figures ▁( p ict ured ▁below ) ▁are ▁considered ▁useful ▁by ▁modern ▁bi olog ists . ▁A ▁rate ▁of ▁about ▁ 1 0 ▁new ▁species ▁discover ies ▁per ▁de cade ▁was ▁observed ▁during ▁the ▁ 2 0 th ▁century . ▁Consider ed ▁the ▁most ▁important ▁research er ▁of ▁si phon op hor es , ▁A .   K . ▁Tot ton ▁introduced ▁ 2 3 ▁new ▁species ▁of ▁si phon op hor es ▁during ▁the ▁mid ▁ 2 0 th ▁century . ▁ ▁On ▁April ▁ 6 , ▁ 2 0 2 0 ▁the ▁Schmidt