Arachnids
The arachnid skeletal system is only made up of an outermost layer. This outermost layer is known as the exoskeleton. Arachnids are joint-legged invertebrates. All arachnids have eight legs. Arachnids also have two pairs of appendages that have changed to feed, defend, and sense more things. Their body is organized into two tagmata called the prosoma, and the opisthosoma. in addition, They also have an internal structure of cartilage-like tissue called the endosternite.