What structures help protect sponges from predators?

Sponges have two and a half basic defense mechanisms: * Spicules - These are structures made of calcium carbonate in some species and glass in others. Usually they are microscopic but in some cases can be larger. read more

Spicules - These are structures made of calcium carbonate in some species and glass in others. Usually they are microscopic but in some cases can be larger. Their main purpose is to support the rest of the sponges tissue but they also serve as an irritant to would be predators. read more

Glass sponges do not produce any toxins, but they live in the very deep ocean where predators are rare. Despite their defenses, sponges can only make slight movements, when they can move at all. They are vulnerable to any organisms that can overcome their defenses and are prey to many species of turtles, fish and invertebrates. read more