Ascidia, also known as sea squirts, are a group of marine invertebrates belonging to the phylum Chordata and class Ascidiacea. These organisms are commonly found in marine environments across the world, living attached to substrates such as rocks, seafloor, or other underwater surfaces.
The typical ascidia body structure consists of a tubular-shaped sac with two openings. The upper opening, called the inhalant siphon, draws in seawater, while the lower opening, known as the exhalant siphon, expels water and waste materials. Ascidia exhibit a wide range of colors, including various shades of red, pink, orange, or yellow, and their sizes can vary from a few millimeters to several centimeters in length.
These unique organisms possess a simple nervous system and possess a distinct tadpole-like larval stage called a "swimming larva" or "tadpole larva," which has a notochord and tail. This, along with other characteristics, classifies ascidia within the phylum Chordata, which also includes vertebrates such as fishes, amphibians, reptiles, birds, and mammals.
Ascidia feed through a filtering mechanism in which they extract organic particles, such as phytoplankton and small zooplankton, from the water using specialized structures called gill slits. They play a crucial ecological role as filter feeders, contributing to the nutrient cycling and purification of marine ecosystems.
Due to their interesting biological characteristics and diverse forms, ascidia have been extensively studied in various fields, including developmental biology, evolutionary biology, and marine ecology. They also hold potential importance in biomedical research due to their ability to regenerate and their capability of producing natural compounds with pharmaceutical applications.
