black spiny urchin, nocturnal to daytimeturnal now?

[bigtankbigfish]

have a black spiny urchin that came in a hitchhiker on a piece of LR about 1.5 yr ago. He used to only come out at night. Now he all over the place even during the day time. He is not losing any spines, what does this mean?

 

[dethsight]

he could have eaten all he can off the rocks that may have hid him, and now is searching elsewhere. i have 3 urchins. a white pincushion, and 2 pencil urchins. the small pencil urchin is almost never out where u can see him readily. the bigger one, however, usually is visible. probably due to his size. the white pincushion urchin isn't moving much right now, i think hes still getting used to the new tank. but, i have seen alot of fish/inverts that claim to be "nocturnal" that are out pretty much all day.

 

[kuja]

Urchins do not have any eyes, so they won't know the difference between day and night. They feel their way around using their tentacles/or arms. I have 3 sea urchins and they move around whenever they feel like it. Perhaps he is moving around more often due to the lack of algae. The more algae eaters you have in your tank the more competition in order to obtain food.