Their common name denotes the threadlike slender body which allows them to virtually disappear among the fine filaments of seaweed, hydroids and bryozoans.

In mature females, brood pouches formed by extensions of the coxae (oostegites) are present on the third and fourth pereonites.

A few species are found in the ocean depths, but most prefer low intertidal zones and subtidal waters among eelgrass, hydroids and bryozoans.

Caprellids are omnivorous, feeding on diatoms, detritus, protozoans, smaller amphipods, and crustacean larvae.

Most species are predators that sit and wait like a praying mantis, with their gnathopods ready to snatch any smaller invertebrates which come along.

They accentuate their adaptive form and colouration by assuming an angular pose, resembling that of the fronds among which they live.

[6] They remain motionless for long periods of time while waiting to ambush their prey, often protozoa or small worms.