Ribbon Of The Rocky Shores – Amphiporus bimaculatus

This unknown is a thin species - - you might say it is "ribbon thin". Amphiporus bimaculatus is a RIBBON WORM, one of several dozen ribbon worm species you can find under rocks along the Western seashores of North America. These thin, non-segmented worms belong to a phylum of their own – Phylum Nemertea, related to Phylum Platyhelmenthes, the flatworms. There are about 900 or so known species of ribbon worms, and most live in on the ocean floor shallow waters .

Most ribbon worms are predators and they are equipped with a long proboscis that can be shot our of the head end to either pierce or entangle prey. The probosis is like an inverted finger on a rubber glove. When deployed to catch its prey it is everted, much like what happens when you blow on the wrist end of a rubber glove to evert one of the fingers.

Ribbon worms are covered with cilia which aid in movement as they slither across rocks and amongst seaweeds. Other ribbon worm species live between sand grains or in crevices on coral reefs. Ribbon worms can stretch, and while they tend to be only a few inches long, one species of ribbon worm was recorded at 30 meters in length! And we're not stretching this observation!

Living ribbon worms can be viewed in our program on Marine Ecology, The Biology of Seashores.