Define filter feeding, fluid feeding, and detrital feeding. Explain the role of parietal cells, chief cells, Paneth cells, and goblet cells in digestion.

Here are the definitions and roles for question 3:

a) Define the following terms:

• (i) Filter feeding: This is a method of feeding where an aquatic animal strains suspended food particles or small organisms from water.
• (ii) Fluid feeding: This is a method of feeding where an animal consumes only liquids, such as nectar, blood, or plant sap.
• (iii) Detrital feeding: This is a method of feeding where an animal consumes detritus, which consists of dead organic matter.

b) Outline the role of the following cells in digestion:

• (i) Parietal cells: Located in the stomach, these cells secrete hydrochloric acid (HCl), which aids in protein digestion and kills bacteria, and intrinsic factor, which is necessary for vitamin B12 absorption.
• (ii) Chief cells: Also found in the stomach, chief cells produce and secrete pepsinogen, an inactive enzyme precursor that is converted to pepsin to digest proteins.
• (iii) Paneth cells: Located in the small intestine, these cells secrete antimicrobial peptides (like defensins) and lysozyme, which help regulate gut microbiota and protect against pathogens.
• (iv) Goblet cells: These cells are found throughout the digestive tract lining and secrete mucus, which lubricates the tract and protects the epithelial lining from digestive enzymes and acids.