SEM (scanning electron microscope) micrographs of Palaeacanthocephala.

<p>(A) Proboscis of male <i>Rhadinorhynchus pristis</i> from <i>Gempylus serpens</i> (Indonesia, Indian Ocean) armed with regular hooks a and basal hook annulus. (B) Praesoma of female <i>R. lintoni</i> from <i>Selar crumenophthalmus</i> (Hawaii, Pacific) with irregular arrangement of trunk hooks. (C) Praesoma of <i>Gorgorhynchoides golvani</i> from <i>Platycephalus arenarius</i> (Indonesia, Indian Ocean) regular arrangement of surface hooks. (D) Habitus of <i>Serrasentis sagittifer</i> from <i>Platycephalus arenarius</i> (Indonesia, Indian Ocean) with hooks are transformed into strong plates arranged as combs. (E) Habitus of <i>Pomphorhynchus laevis</i> from <i>Platichthys flesus</i> (Baltic Sea) shows any trunk hooks on bulb, neck and trunk. (F) Praesoma of <i>Bolbosoma vasculosum</i> from <i>Lepturacanthus savala</i> (Indonesia, Indian Ocean) formed in the shape of a bulb, and armed with regular hooks which are arranged in two rings. Scale bars: A 400 µm, B, D, F, 200 µm, E 100 µm.