Tunicata, commonly known as tunicates or sea squirts, refers to a phylum of marine animals that belong to the chordate group. They are filter-feeding organisms characterized by a soft, sac-like body covered by an outer tunic made of cellulose-like materials. The term "tunic" in their name originates from this unique protective covering.
Tunicates exhibit a wide range of forms, from small, solitary species to large colonies. They are predominantly found in marine environments, particularly in shallow waters, attached to rocks, docks, or other substrates. While they lack a complex vertebral column like other chordates, they possess a notochord during their larval stage, which supports the body and elongates it. However, as they develop into adults, the notochord generally disappears in most species, leaving just a vestige to distinguish them as chordates.
In terms of feeding, tunicates actively filter small particles from the water, using a mucous-covered structure called a pharynx. This pharynx functions as a sieve, allowing them to trap microscopic organisms and organic matter, which they ingest.
Tunicates play important ecological roles in marine ecosystems as filter feeders, contributing to water filtration and nutrient cycling. They provide shelter and habitat for other marine organisms, and their soft tissues are consumed by various animals.
Due to their distinct characteristics and complex life cycle, tunicates have attracted scientific interest and have served as models in developmental biology studies. Understanding their evolutionary relationships and ecological importance remains a subject of ongoing research.
