Crevices are beneficial to digestive ability and growth of juvenile sea cucumbers Apostichopus japonicus

Crevices serve as a natural congregation site for sea cucumbers. Short-term exposure to the crevices enhances feeding and defecation behaviors of sea cucumbers. However, the long-term effects on digestive ability and growth remain entirely unknown. In this study, we investigated the effects of crevices on the growth and digestive ability of juvenile sea cucumber over a 60-day cultivation period. Crevices significantly increased the muscle layer thickness, mucosal layer thickness, fold length, and fold width in the intestines of sea cucumbers. These findings suggest that crevices improved the intestinal micromorphology of sea cucumbers. Sea cucumbers reared within crevices exhibited significantly elevated pepsin activity compared to those cultured without crevices. Crevices probably play a beneficial role in food digestion by improving intestinal micromorphology and pepsin activity in sea cucumbers. Furthermore, this study found a significant increase in relative weight gain rate (WGR) and relative body wall rate (BWR) among sea cucumbers inhabiting crevices, in contrast to those devoid of such habitats. In summary, the present study reveals that crevice is an effective approach to enhancing the digestive ability and growth of juvenile sea cucumbers.