Commensalism is a form of nutritional relationship between tow living organisms in which one of the organisms (the commensal) benefits and the other is unaffected in any way.
<em>In this case, the shrimp benefit from the sea cucumber by getting its shelter and get moved around while the sea cucumber is not in any way affected.</em>
Because the winter is cold and little body fat and a dark colored fur will get it killed faster, but long ears can help the bunny hear the danger but I don't think there will be any predetors out in the harsh snow.