Figure 1From: The hatching larva of the priapulid worm Halicryptus spinulosusA/B Adults with fully protruded introvert of the priapulid worms Halicryptus spinulosus (A) and Priapulus caudatus (B). Anterior is to the left in both cases. The posterior structure in A (arrow) is excrement, not a caudal appendage as seen in B (asterisk). C Simplified phylogeny of the Priapulida (after [19]). D Embryo of H. spinulosus one day before hatching. View on inner organs like the developing gut is inhibited by large amounts of yolk. Anterior is to the top.Back to article page