surrounds sucker ring Suckers of decapodiforms have two types of hard, horny rings. One, the inner ring, lies around the inner walls of the acetabulum and often bears teeth. The other, the outer ring, is composed of numerous platelets and lies on the surface of the infundibulum. horny ring of sucker A chitinous ring that encircles a sucker. Found in cuttlefishes and squids sucker anatomical structure