[Chaetognatha] Slightly claw shaped, curved, hard structures at the anterior of the head (head, dorsal view).

[Polychaeta] Stout-shafted simple chaetae which may be distally curved or toothed.

[Gastropoda general] Chitinous teeth placed in evaginable sacs (the hook sack) at both sides of the radula probably modified parts of the jaw found in most Gymnosomata; the hook sacs are buccal organs in the head under the hood and are evaginable.

[Pteropoda] Chitinous teeth located in evaginable sacs (hook sack) at both sides of the radula, under the hood (probably modified parts of the jaw), present in most Gymnosomata (Pneumodermopsis in ventral view).

[Cepahalopoda] Chitinous claw-like structures ontogenetically derived from the suckers on the arms and/or clubs of some squids (Ce 1C).

Alternative forms for Hook : [Cephalopoda] Hooks (pl.), [Chaetognatha] grasping hooks, [Chaetognatha] grasping spines, [Chaetognatha] H, [Chaetognatha] hooks, [Pteropoda] hook sac, [p][/p], [p][/p], [p][/p].