It is well known that the functions of the covering behavior of sea urchins include protection against predation, waves and avoiding over-exposure to light and particles. However, the effects of the covering behavior on fitness traits of sea urchins are not known. This lack prevents our understanding the selective pressure for the covering behavior of sea urchins. The evolutional drives of the covering behavior of sea urchins require studying the effects on fitness traits. The present study investigated the effects of covering behavior on food consumption, growth and gonad traits in comparison to the effects of the sheltering behavior in Glyptocidaris crenularis. Our study had three treatments: sea urchins with access to covering material (shells of the clam Ruditapes philippinarum), sea urchins with access to shelter (bricks) and sea urchins without access to shells or shelter. Food consumption, growth and gonad traits were measured. Food consumption of the sea urchins that covered themselves with shells was significant higher than that in the group with access to shelter (P<0.05). However, food consumption in the groups with shells or shelter was not significantly different from the group without shells or shelter (P>0.05). The three groups showed no significant difference in survival (P>0.05). Sea urchins in the groups with or without shells had a significantly higher test diameter, test height, wet body weight, wet gonad weight, dry gonad weight, gonad index, wet test weight, dry test weight, wet lantern weight and dry lantern weight than those with access to shelter (P<0.05). However, no significant difference of these traits was found between the groups with shells and without shell or shelter (P>0.05). The lantern index of sea urchins in the group without access to shells or shelter was significant lower than those with access to shells or shelter (P<0.05). There were no significant differences in the traits for the two groups (P>0.05). In the present study, we found negative effects of sheltering behavior of the sea urchins compared to the group with no access to shells or shelter. No such negative impacts were found on the individuals covering themselves with shells. The present study provides evidence on the differences between covering and sheltering behaviors. The effect of the covering behavior on growth and gonad traits were significantly different from those of the sheltering behavior in G. crenularis. The results of this study also indicate that the covering behavior represents an adaptation of G. crenularis in adverse environmental conditions. However, we should be aware that the present study is far from knowing the selective pressure of the covering behavior in G. crenularis. Further studies should be done to understand the evolutional drives of the covering behavior of G. crenularis.