The secretion from Hatschek's pit cells help entrapping food particles in the water.Complete answer: Amphioxus
is a modern representative of the Cephalochordata subphylum.
It is a marine Chordate animal. Zoologists take much interest in these animals because they provide evolutionary facts about the origins of vertebrates. These are commonly known as ‘sea lancelets’ due to their characteristic shape of head.
They contain many organs and systems that closely resemble those of modern fishes, though in a primitive form. The gill-slits of sea lancelets are used for feeding, not for respiration. Their circulatory system transports food throughout their body, though it does not have RBC or haemoglobin.
The roof of the oral hood in Amphioxus
shows the presence of a unique structure. Here, the second rostral groove is known as Hatschek's pit. It should not be confused with Hatschek’s nephridium. Hatschek's pit is a deep ciliated fossa on the dorsal midline of the buccal cavity. Studies have shown the presence of some granulated cells in the epithelial lining of this pit. Along with ciliated cells it is responsible for the secretion of mucus. The secreted mucus helps to entrap food particles from the water.So, the correct answer is C. Mucus.Note:
Feeding method of Amphioxus
is a reflection of their habitat; they expose their anterior portion to the water and feed on plankton by the action of branchial ciliary current which passes water through the mucous sheet- this is called filter-feeding.