The reason this is a significant achievement is that the DNA of living cells in the organism were "edited" to remove the pigmentation, thereby effectively changing the phenotype of an adult squid.
we determined whether a TDO-selective inhibitor (680C91) impeded pigmentation in developing embryos. The development of D. pealeii has been divided into 30 stages and eye pigmentation appears at ∼stage 25, while chromatophore pigmentation starts at stage 26 [21]. We added 680C91 to developing embryos at stage 20
Knocking out TDO in squid embryos efficiently eliminated pigmentation. By precisely timing CRISPR-Cas9 delivery during early development, the degree of pigmentation could be finely controlled.