The polysaccharide and protein contents and secretion were detected in surface mucus of echiuran worm Urechis unicinctus with body weight of 2.75 g in a wet sand plastic box with and without water at temperature of 15, 20, 25, and 30 ℃ by phenol-sulfuric acid method and total protein assay kit, and the antibacterial activity of mucus to routine pathogens Staphylococcus aureus, Vibrio splendidus, Bacillus mirabilis, Enterobacter aerogenes, Aerobacter cloacae, V.harveyi, V.parahaemolyticus, V.anguillarum, and Micrococcus luteus in aquatic animals was tested by comparing the diameter of the bacteriostatic zone to evaluate air exposure tolerance and characteristics of surface mucus in echiuran worm in wet sand with and without water. It was found that the surface mucus secretion was decreased with the increase in temperature, and that there was stronger tolerance to air exposure in the echiuran worm in wet sand without water than that in the echiuran worm in wet sand with water, the maximal surface mucus secretion in 10 individuals in 10 min(2.85 mL0.04 mL) in echiuran worm in wet sand with water and in 1 min(3.33 mL0.05 mL ) in echiuran worm in wet sand without water at 15 ℃. The maximal contents of polysaccharide (1.04 mug/mL0.10 mug/mL) and protein (65.81 mg/mL2.22 mg/mL) were observed in 30 min in echiuran worm in wet sand without water, with a tendency of first increase and then decrease. No antimicrobial activity of the mucus to the tested 9 pathogens was found. The findings indicate that the echiuran worm with body weight of 2.75 g can tolerate air exposure for more than 48 hours under the condition of wet sand without water at 15 ℃.</p
