acorn worm

or acorn·worm

noun

1. any of several burrowing, often brilliantly colored hemichordates of the class Enteropneusta, usually found in intertidal sand and mud, having an acorn-shaped proboscis and collar.

acorn worm

noun

1. any of various small burrowing marine animals of the genus Balanoglossus and related genera, having an elongated wormlike body with an acorn-shaped eversible proboscis at the head end: subphylum Hemichordata (hemichordates)

Word History and Origins

Origin of acorn worm¹

First recorded in 1885–90

Example Sentences

To locate the parts of the starfish body where head-coding genes are active, the researchers compared the genetic markers in a small Patiria miniata sea star with Saccoglossus kowalevskii, a species of acorn worm that is closely related to starfish and that has a well-studied genome.

From Scientific American

The researchers found that the genes in the head region of the acorn worm were “switched on” in the starfish’s bumpy skin, which covered its entire body.

From Scientific American

The enteropneust, also known as an acorn worm, lurks at the bottom of the Sirena Canyon.

From Time

This creature is called an "acorn worm."

From National Geographic

In fact, this acorn worm is more closely related to sea stars and vertebrates like fish than it is to an earthworm.

From National Geographic