Ascidiidae
Ascidiidae is a family of tunicates, commonly known as sea squirts or ascidians. These marine invertebrates are filter feeders and are found in a wide range of habitats, from shallow coastal waters to deep-sea environments. Ascidiidae are characterized by their sac-like bodies with two siphons: an incurrent siphon for drawing in water and an excurrent siphon for expelling water and waste. They are typically solitary, but some species form colonies.
Characteristics
Ascidiidae are distinguished from other tunicates by several key features:
- Solitary or colonial: While most Ascidiidae species are solitary, some form colonies with individuals connected by a common tunic.
- Body shape: Ascidiidae typically have a sac-like body, often with a distinctive, cylindrical shape.
- Siphons: They possess two siphons: an incurrent siphon (also known as the oral siphon) for drawing in water and an excurrent siphon (also known as the atrial siphon) for expelling water and waste.
- Tunic: The body is covered by a tough, protective outer layer called a tunic, which is composed of a cellulose-like substance called tunicin.
- Internal structure: Internally, Ascidiidae possess a pharynx with gill slits, a digestive tract, and a simple nervous system.
Environments
Ascidiidae are found in a wide range of marine habitats, including:
- Intertidal zones: They can be found attached to rocks, piers, and other solid substrates in the intertidal zone, where they are exposed to fluctuating water levels.
- Subtidal zones: Ascidiidae also inhabit the subtidal zone, which is below the low tide mark, where they are constantly submerged.
- Deep-sea environments: Some species are found in deep-sea environments, where they may colonize a variety of substrates, including hydrothermal vents and cold seeps.
References
For further information on Ascidiidae, refer to the following reliable online sources: