Genetic studies have shown that genes directing anterior-most development are expressed along ambulacra in the center of starfish rays, with the next-most-anterior genes expressed in the surrounding fringe of tube feet. Genes related to the beginning of the trunk are expressed at the ray margins, but trunk genes are only expressed in interior tissue rather than on the body surface. This means that a starfish body can more-or-less be considered to consist only of a head.
Genetic studies have shown that genes directing anterior-most development are expressed along ambulacra in the center of starfish rays with the next-most-anterior genes expressed in the surrounding fringe of tube feet Genes related to the beginning of the trunk are expressed at the ray margins but trunk genes are only expressed in interior tissue rather than on the body surface This means that a starfish body can more-or-less be considered to consist only of a head