Those animals with backbones have a much more developed skeletal structure and tend to be stronger than invertebrates. Therefore, invertebrates have to look for other means to protect themselves from danger.
Many invertebrates have strong shells that substitute for a backbone. These external structures play an important role in their survival. The shells protect the invertebrates from predators. They also prevent their bodies from drying up when they are out of water.
Other invertebrates have developed various ways to defend themselves. Some brightly coloured sea slugs taste so terrible that other animals do not want to eat them. Sea anemones possess numerous stinging tentacles, and sharp spines shield the sea urchins body. These are just some of the ways by which invertebrates survive.
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