The upper or aboral surface is smooth, and its colour is usually red, orange, grey, or pale brown, sometimes with paler patches.

In British Columbia, about half of its diet consists of leather stars (Dermasterias imbricata), which move too slowly to evade it.

They have numerous tiny pincer-like organs called pedicellariae and coil their arms around the morning sun star, nipping it with these.

Another sometimes successful defence strategy is used by the slime star (Pteraster tesselatus) which inflates its aboral surface making it difficult for the attacker to get a grip on it and at the same time exudes copious amounts of noxious mucus.

[2] If grabbed, the sunflower star may leave one of its arms behind, a process called autotomy, sacrificing this limb to make its escape.