Question

The model of feeding in cephalochordates is
A) Ciliary
B) Tentacular
C) Flagellar
D) None of the above

Answer 1

Hint: Cephalochordates are the animals that belong to the chordates. The cephalochordates like Amphioxus and lancelets are called filter feeders. Cephalochordates have developed a filter-feeding system is called the oral hood, it serves as the entrance for the incoming food particles. The free edge of the oral hood contains Buccal cirri and a small filament.

Complete answer:
Cephalochordate is also known as acrania. More than two dozen species belongs to the subphylum Cephalochordata of phylum Chordata. There are about 20 species in two families, each containing a single genus.

Cephalochordates and vertebrates are having a hollow, dorsal nerve cord, pharyngeal gill slits and notochord. In most vertebrates the embryonic notochord is eventually replaced by bony vertebrae or cartilaginous tissue, among cephalochordates, the notochord is retained into adulthood and is never removable by vertebrae.

Branchiostoma was known as Amphioxus, which is a name that is retained as an informal term. They are called filter feeders as they have a system called the oral hood through which the food enters the organism. These organisms use cilia to generate a current of water. The water is entered through the ciliary current into the mouth of the organisms and the microorganisms are filtered from the water.

Tentacular-Tentacles are the elongated organs that are flexible and are present near the mouth. It serves the function of feeding or grasping. These are present in invertebrates like the hydra.

Flagellar-Flagella is a whip-like appendage that is mostly used for locomotory purposes. Protozoans use flagella along with the collar for feeding.

Therefore, the correct answer is option ‘A’ i.e, Ciliary.

Note: Cilia are mainly the locomote organs that help the organisms to move in the water. The feeding with the help of cilia is known as ciliary feeding. The molluscs also exhibit ciliary feeding.