Chapter 23: Question 7

Both sea squirts (urochordates) and lancelets (cephalochoradates) are filter-feeding organisms. Describe the filter-feeding apparatus of a sea squirt and explain in what ways its mode of feeding is similar to, and different from, that of amphioxus.

Sea squirts filter feed by formation of a mucous net this is secreated by a glandular groove. The endostyle located along the midventral side of the pharynx. Cilia on the gill bars of pharynx pull mucous into a sheet that spreads dorsally across the inner face of the pharynx. Food particles brought in the incurrent openings are trapped in the mucous net, which is worked into a rope and carried posteriorly by cilia into esophagus and stomach. It is similar to amphioxus because they both use a mucous net, and cilia . It is different because The food particles are separated from the mucous and passed to the hepatic cecum, where they are phagocytized and digested intracellularly. Nathan Tingler

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