Identification and Distribution of Some Monoamines in Tissues of the Sunflower Star, Pycnopodia Helianthoides (Echinodermata)

The distribution of some monoamines in the tissues of an echinoderm, the sunflower starfish, Pycnopodia helianthoides, has been investigated in order to ascertain whether monoamine levels are similar to those found in other Deuterostomia. Dopamine, noradrenaline and octopamine were present in the arm nerves at concentrations of 5954 ng/g, 2133 ng/g and 260 ng/g respectively. The octopamine/ noradrenaline ratio for the arm nerve was 0.12 and thus similar to the typical mammalian (deuteros‐tome) ratio rather than the higher invertebrate (protostome) ratio. Trace amounts of p‐tyramine, β‐phenylethylamine were also present. 5‐Hydroxytryptamine was not detected but tryptamine was present in high concentrations (1251 ng/g).