Sea Squirt – Ascidia sydneiensis

The Sea Squirt – Ascidia sydneiensis is a solitary tunicate belonging to the class Ascidiacea. These marine invertebrates are filter feeders that play an important role in their respective ecosystems.

Description & Characteristics

Ascidia sydneiensis, commonly known as the Sea Squirt, exhibits a distinctive morphology. These sessile animals are typically found attached to hard substrates like rocks, shells, or even piers. Their body, which can reach a maximum size of 10 cm in length, is encased in a tough, leathery tunic. The tunic serves as a protective outer layer and is often covered in various algae and other organisms.

Habitat and Occurrence

The Sea Squirt – Ascidia sydneiensis thrives in a variety of marine environments, particularly in shallow coastal waters. They are commonly found in intertidal zones, estuaries, and rocky reefs. Their preferred habitat ranges from the low intertidal to depths of approximately 10 meters, making them adaptable to both exposed and sheltered areas. This wide depth range enables them to inhabit both the subtidal and intertidal marine zones, showcasing their ability to thrive in diverse ecological niches.

Taxonomy

The Sea Squirt – Ascidia sydneiensis belongs to a complex taxonomic classification. The species is part of the Family: Ascidiidae, which encompasses a wide range of solitary ascidians. The family Ascidiidae is further categorized under the Order: Phlebobranchia, which distinguishes them based on their internal gill structure and other anatomical features. The Order Phlebobranchia is nested within the Class: Ascidiacea, a large group of tunicates that includes both solitary and colonial forms.

Feeding

The Sea Squirt – Ascidia sydneiensis is a filter feeder, relying on microscopic organisms like plankton for sustenance. They draw water into their bodies through an incurrent siphon, filtering out food particles before expelling the water through an excurrent siphon. Their diet consists primarily of phytoplankton and zooplankton, making them integral to the marine food web.