scanning electron microscopy of proboscis of cathayacanthus spinitruncatus
the notable feature of acanthocephala presence of anterior, protrudible proboscis covered spiny hooks (hence common name: thorny headed worm). proboscis bears rings of recurved hooks arranged in horizontal rows, , means of these hooks animal attaches tissues of host. hooks may of 2 or 3 shapes, usually, longer, more slender hooks arranged along length of proboscis, several rows of more sturdy, shorter nasal hooks around base of proboscis. proboscis used pierce gut wall of final host, , hold parasite fast while completes life cycle.
like body, proboscis hollow, , cavity separated body cavity septum or proboscis sheath. traversing cavity of proboscis muscle-strands inserted tip of proboscis @ 1 end , septum @ other. contraction causes proboscis invaginated cavity. whole proboscis apparatus can be, @ least partially, withdrawn body cavity, , effected 2 retractor muscles run posterior aspect of septum body wall.
some of acanthocephalans (perforating acanthocephalans) can insert proboscis in intestine of host , open way abdominal cavity.
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