Didemnum
Didemnum is a genus of colonial tunicates, commonly known as sea squirts, that are widespread in marine environments. These organisms are known for their ability to form large, dense mats that can quickly cover surfaces, potentially impacting native marine ecosystems.
Common Names
Didemnum species are often referred to as "sea squirts" or "colonial tunicates". Some species have specific common names, such as "golden star tunicate" (Didemnum molle) and "invasive golden star tunicate" (Didemnum vexillum).
Characteristics
Members of the Didemnum genus are characterized by their colonial nature, forming large, gelatinous mats composed of numerous individual zooids (small, filter-feeding organisms). These mats can range in color from white to yellow, orange, or brown. The zooids are embedded within a shared tunic, a tough, protective outer layer.
Didemnum species are filter feeders, using a system of siphons to draw in water and extract food particles. They reproduce both sexually and asexually. Sexual reproduction involves the release of sperm and eggs, while asexual reproduction occurs through budding, where new zooids are produced from existing ones.
Environments
Didemnum species are found in a variety of marine environments, including:
- Rocky shores
- Seagrass beds
- Coral reefs
- Man-made structures (e.g., docks, piers)
Some species, such as Didemnum vexillum, are considered invasive and have spread rapidly in various regions, potentially displacing native species and impacting biodiversity.
References
For more information on Didemnum, refer to the following resources: