Do spiders have bones?
No, spiders do not have bones. Like insects and other arthropods, they have a hard outer shell called an exoskeleton that supports and protects their bodies.
A spider's exoskeleton is made largely of chitin, a tough, lightweight material. It acts like armor and gives muscles something to attach to. Because the exoskeleton cannot grow, spiders must shed it several times as they grow, a process called molting. After molting, their new exoskeleton is soft for a while, making them vulnerable.
Spiders move their legs in an unusual way. Muscles bend the legs inward, but many leg joints have no muscles to straighten them. Instead, spiders pump fluid into their legs to extend them, using hydraulic pressure. This is why dead spiders often curl up their legs.
Spider bodies
A spider's body has two main parts: the cephalothorax, which holds the eyes, mouthparts and legs, and the abdomen, which contains the silk glands. Most spiders have eight eyes, though some have six, four, two or even none.
Did You Know?
Some jumping spiders can leap more than 50 times their body length using quick bursts of fluid pressure in their legs.