dactylozooid

from The Century Dictionary.

• noun One of the members of a colony of Hydrozoa whose function is to capture food for the gastrozoöids. or nutritive members of the colony.
• noun In zoology, an occasional elongated appendage of hydrozoans, devoid of a mouth and gastric cavity, and having a simple tentacular function: so called from its shape.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) A kind of zooid of Siphonophora which has an elongated or even vermiform body, with one tentacle, but no mouth. See siphonophora.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun zoology A kind of zooid of Siphonophora with an elongated or even vermiform body, with one tentacle, but no mouth.