The relationship between seaweed diet and purple ink production in Aplysia dactylomela rang, 1828 from Northeastern Brazil

Journal of Shellfisheries Research, August, 2004 by Luis Ernesto Arruda Bezerra, Ana Fontenele Urano Carvalho, Luciana Aires Barreira, Vanessa Lucia Rodrigues Nogueira, Jose Roberto Feitosa Silva, Ilka Maria Vasconselos, Vania Maria Maciel Melo

CONCLUSIONS

The sea hare A. dactylomela, and possibly other Aplysia species, needs to consume red seaweeds to be able to secrete the purple ink. The pigment is from algal origin; whereas, the proteins are not. The protein content and composition seem to be always the same, regardless of the seaweed species consumed.

TABLE 1.
Chemical analysis of the purple ink from Aplysia dactylomela.

Components                     % Dry Basis

Total protein (N x 6.25)   64.87 [  or -] 2.56
Reduced carbohydrate        9.07 [  or -] 1.84
Lipid                       2.20 [  or -] 0.40
Ash                         2.72 [  or -] 0.20

Values are means [  or -] standard deviation of at least
triplicate analyses.

TABLE 2.
Amino acid composition of purple ink of Aplysia dactylomela

   Amino       g of Amino Acid in
Acid Residue   100 g of Dry Matter

    Ala                6.03
    Arg                5.07
    Asx               11.77
    Cys                1.43
    Glx               11.95
    Gly                6.48
    His                1.12
    Ile                3.68
    Leu                7.10
    Lys                4.70
    Met                1.55
    Phe                4.55
    Pro                8.98
    Ser                5.78
    Thr                7.54
    Trp                ND
    Tyr                5.46
    Val                7.59

ND = not determined.

ACKNOWLEDGMENTS

The authors thank PET/CAPES for a BS fellowship to L.E.A. Bezerra, CNPq for grants received and to the students R.C.N. Amorim, J.E.A. Beserra-Jr, and M. Thadeo for their assistance during the field work.

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