Enopla is one of the classes of the worm phylum Nemertea, characterized by the presence of a peculiar armature of spines or plates in the proboscis.
The enoplan nemerteans have been regarded as highly derived based on a more complicated muscle arrangement in the body wall and a more complex nervous system.
The encompasses those animals with a proboscis armature consisting of a single central stylet on a large cylindrical basis.
The Polystilifera are further divided in two taxa, one (Pelagica) containing the pelagic species, and the other (Reptantia) with crawling or burrowing forms.
Its normal movement is gliding over the surface by help of cilia on the ventral side in combination with mucus produced by the worm.
An easy way of collecting nemerteans is to place seaweed and smaller algae in a bucket of sea water and let it stand for a few hours, and up to a couple of days, depending on weather and temperature.
The worms will crawl to the sides of the bucket, where they are easily observed and collected, as the oxygen concentration decreases in the water.
Enoplan nemerteans do not appear to be equally common sublittorally, but this may be a result of biased sampling (less accessible environments).
The majority of enoplan ribbon worms are marine and benthic, but there are approximately 100 named and described species of pelagic nemerteans.
Freshwater hoplonemerteans are known to feed on oligochaetes, unicellular organisms, insect larvae, and other crustaceans.
There is one group of parasitic enoplan nemerteans (family Carcinonemertidae) found among the egg masses of certain crab species that feed on the host's embryos.
Mode of spawning is unknown for most species, but where known, it ranges from widespread release of gametes into surrounding waters, to pseudocopulation with eggs attached in a gelatinous matrix to a benthic substratum.
Some of these toxins, originally found in a nemertean, have been synthesized and tested in pre-clinical trials as a possible memory enhancer in the treatment of Alzheimer's disease.