Paracatenula
| Paracatenula | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Platyhelminthes |
| Class: | Turbellaria |
| Order: | Catenulida |
| Family: | Retronectidae |
| Genus: |
Paracatenula Sterrer and Rieger, 1974 |
Paracatenula is a genus of millimeter sized free-living marine gutless catenulid flatworms.
Paracatenula is found worldwide in warm temperate to tropical subtidal sediments. They are part of the interstitial meiofauna of sandy sediments. Adult Paracatenula lack a mouth and a gut and are associated with intracellular symbiotic alphaproteobacteria of the genus Cand. Riegeria. The symbionts are housed in bacteriocytes in a specialized organ, the trophosome (Greek. τροφος trophos ‘food’). The bacteria can make up half of the worms' biomass. The benefitial symbiosis with carbon dioxide fixing and sulfur-oxidizing endosymbionts allows the marine flatworm to live in nutrient poor environments.
Five species of Paracatenula have been described - P. erato, P. kalliope, P. polyhymnia, P. urania and P. galateia, named after muses and nymphs of the Greek mythology. Several more species have been morphologically and molecularly identified, but are not formally described.
Paracatenula are globally distributed in warm temperate to tropical regions and have been collected from Belize (Caribbean Sea), Egypt (Red Sea), Australia (Pacific Ocean) and Italy (Mediterranean Sea). They occur in the oxic-anoxic interface of subtidal sands and have been found in water depths up to 40 m.
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