Stylet (zoology)

A stylet is a hard, sharp, anatomical structure found in some invertebrates.

For example, the word stylet or stomatostyle is used for the primitive piercing mouthparts of some nematodes[1] and some nemerteans.

In these groups the stylet is a hardened protrusible opening to the stomach.

The mouthparts of tardigrades, diptera and aphids[2] are also called stylets.

[3] In octopodes, the stylets are internal, needle-like bent rods within the mantle, the vestigial remnants of an external shell.