List two functions of the pharynx in tunicates.
The correct answer and explanation is :
Two Functions of the Pharynx in Tunicates:
- Filter Feeding – The pharynx in tunicates plays a crucial role in feeding by filtering plankton and other microscopic particles from the water.
- Respiration – The pharynx also serves as a respiratory organ, facilitating gas exchange by allowing oxygen to diffuse into the bloodstream and carbon dioxide to be expelled.
Explanation:
Tunicates, also known as sea squirts, are marine invertebrates belonging to the subphylum Urochordata. They have a specialized structure called the pharyngeal basket, which is a perforated and ciliated pharynx that performs both feeding and respiration.
1. Filter Feeding
Tunicates are suspension feeders, meaning they extract food from water. The pharynx is lined with numerous gill slits (stigmata) and coated with mucus, secreted by the endostyle. Water enters through the incurrent siphon and passes through the pharynx, where food particles become trapped in mucus. Cilia lining the pharynx then transport the mucus with trapped food toward the esophagus, where it is digested. This adaptation allows tunicates to efficiently extract nutrients from water.
2. Respiration
The perforations in the pharynx also facilitate respiration. As water flows through the pharyngeal slits, oxygen diffuses into the surrounding blood vessels while carbon dioxide is expelled. The pharyngeal basket acts similarly to gills in fish, ensuring continuous gas exchange. The efficient circulation of water through the pharynx allows tunicates to survive in various marine environments.
Thus, the pharynx in tunicates is a multifunctional organ, essential for both feeding and breathing, ensuring survival in their sessile (attached) lifestyle.