#eunicidae

Stop a Moment for the Sand Striker

Also known as the bobbit worm, Eunice aphroditois is a marine bristle worm endemic to both the Atlantic and Pacific oceans, in waters up to 95 m (311 ft) deep. Because they spend most of their time under ground, the sand striker is rarely seen. However, they can be found in both coral reefs and deeper, rocky or sandy ocean floors-- anywhere they can hide and ambush prey.

This species of bristle worm is famous for its hunting methods. Individuals live in burrows deep under ground, with an entrance covered by sand or rocks, and only emerge at night. They keep these burrows stable by secreting a mucus-like substance which coats the sandy walls and keeps them in place. Because their eyes are rudimentary at best, sand strikers use their five antennae to sense passing prey-- usually fish, but also algae or organic debris. When their target is close enough, E. aphroditois ambushes it and drags it back down into the burrow with its large mandibles. This process is extraordinarily fast; bobbit worms have been clocked moving at 6 m (20 ft) per second. The mandibles are also retractible, which helps the bobbit worm swallow its prey.

Though only their heads are usually visible, the sand striker has an impressive body. They can grow to be 1- 3 m (3-10 ft) long, although they’re typically only 25 mm (1 in) wide. Like other bristle worms, their bodies are made up of segments, protected by a hard, irridescent exoskeleton. Most sand strikers are deep purple or black, although individuals in a variety of colors have been documented. In addition to their exoskeleton, bobbit worms also sport sharp, venomous tentacles down the length of their body to deter threats. Adults are typically avoided by other, larger predators, but juveniles can be targeted by fish.

E. aphroditois lacks external reproductive organs, and instead is a broadcast spawner. When they’re ready to mate, female sand strikers produce a pheromone that attracts males and signals them to release their sperm. The females them release their eggs into the water, where they become fertilized and develop into larvae. These larvae swim freely for several months to a year, during which many become food for other animals. The survivors begin to segment and burrow into the sand, where they become sexually mature. In the wild, bobbit worms can live anywhere from 3-5 years, though some biologists believe they may have a longer lifespan of 10-15 years.

Conservation status: E. aphroditois has not been evaluated by the IUCN. However, populations in coral reefs are threatened by habitat decline.

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Photos

Richard Zerpe

Department of Biomedicine, University of Basel

Bobbit worm (Eunice aphroditois)

MARINE WORMS ARE EATING MARINE DEBRIS AND CREATING MICROPLASTICS

Buoys of expanded polyestyrene (EPS), are often used in the aquaculture industry, and after time, slowly disintegrate under the influence of sunlight, weather, and animals too. According to a recent study, bristle worms (polychaetes) showed their are eating particles of polyestyrene from buoys, and then excreting microplastics.

Researchers found a lot of EPS particles in the feces of polychaetes from EPS debris, they noted polychaetes burrowed into EPS debris and created numerous EPS microplastic particles, this mean theses organisms are inhabiting marine debris and contributing to microplastic formation.

-  Marphysa sanguinea is a common polychaete worm, with two strong black teeth (seen in picture a). This one measures 22 cm, and was collected from EPS buoy debris. EPS particles are clearly seen inside polychaete digestive tract (b), and in feces (c).

According to researchers, polychaetes burrowed into the blocks and created numerous EPS particles, indicating that a single polychaete can produce hundreds of thousand f microplastics particles per year. These finding reveal the potential role of marine organisms as microplastics producers in the marine environments.

Photo of a Marphysa sanguinea by Peter J. Bryant

Photo by craigjhowe

Photo by Frédéric ANDRE