Phoronis
Phoronis is a genus of marine, sedentary, tube-dwelling, filter-feeding worms that belong to the phylum Phoronida. They are often called “horseshoe worms” due to their horseshoe-shaped lophophore, which is a crown of tentacles used for feeding. These worms are small, typically ranging in size from a few millimeters to a few centimeters, and are found in a variety of marine environments, including shallow waters, deep-sea vents, and even within the tissues of other marine organisms.
Characteristics
Phoronis worms have a distinctive horseshoe-shaped lophophore, which is a crown of tentacles that surrounds their mouth. The lophophore is used to filter food particles from the water, and it is also used for gas exchange. The worms have a U-shaped gut, with the mouth and anus located at the same end of the body. They also have a simple circulatory system and a nervous system.
Phoronis worms are typically found in tubes that they construct themselves from a gelatinous material. The tubes are often attached to rocks, shells, or other surfaces. Some species of Phoronis are able to burrow into soft sediments.
Environments
Phoronis worms are found in a wide range of marine environments, including:
- Shallow waters
- Deep-sea vents
- Coral reefs
- Intertidal zones
- Estuaries
Reproduction
Phoronis worms reproduce sexually. They release sperm and eggs into the water, where fertilization occurs. The larvae develop into free-swimming trochophores. The trochophores eventually settle and develop into adult worms.
References
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4201870/
[2] https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/phoronis
[3] https://en.wikipedia.org/wiki/Phoronida