Urechidae
Urechidae is a family of marine worms belonging to the phylum Annelida. They are commonly known as “spoon worms” or “peanut worms” due to their distinctive body shape. Urechids are burrowing invertebrates found in intertidal and subtidal sediments worldwide, playing an important role in marine ecosystems by contributing to sediment turnover and nutrient cycling.
Characteristics
Urechid worms are characterized by their elongated, cylindrical body with a spoon-shaped anterior end. Their bodies are typically 2-15 centimeters long, with a smooth, fleshy exterior. They lack external segmentation and have a simple, unspecialized head with a mouth opening at the anterior end. Unlike most annelids, Urechidae lack parapodia, the lateral appendages that are common in other annelid groups.
These worms are burrowing animals, creating U-shaped burrows in soft sediments. They are filter feeders, using their spoon-shaped anterior end to capture food particles from the surrounding water. Their digestive system is simple and includes a pharynx, esophagus, stomach, and intestine. Urechids also possess a closed circulatory system and a well-developed nervous system.
Environment and Distribution
Urechid worms are found in a wide range of marine environments, from intertidal zones to deeper subtidal waters. They are most abundant in soft sediments, such as sand, mud, and silt. Urechid species have a global distribution, with representatives found in all major oceans.
Ecology
Urechid worms play an important role in marine ecosystems by contributing to sediment turnover and nutrient cycling. Their burrowing activities help to aerate the sediment and increase its permeability. Their feeding habits also contribute to the redistribution of organic matter within the sediment. Some species, such as Urechis caupo, are commercially harvested as a food source in some regions.
References
For more information about Urechidae, consult the following references: