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How do cephalochordates obtain food?
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Chordate
X-ray fish (Pristella maxillaris), is an example of a chordate with a visible backbone.
Cephalochordates, also known as lancelets or amphioxi, are suspension feeders that obtain food by filtering small particles from the water. Typically found buried in sandy or muddy substrates, they position their anterior end above the surface to feed.123
The feeding process involves the following steps:
- Water Intake: The mouth is surrounded by an oral hood lined with buccal cirri, which act as a grid to screen out particles that are too large to consume. Cilia on the gill slits beat to draw a current of water into the mouth and through the pharynx.132
- Trapping Food: An endostyle located on the floor of the pharynx secretes a sheet of mucus. This mucus traps suspended food particles as the water passes through the gill basket.123
- Digestion: The food-laden mucus is transported to the gut, where it is digested and absorbed. Unlike other chordates, cephalochordates are capable of phagocytosis, a process where individual cells envelop food particles. The water then exits the body through the atriopore.132