Many insects and crustaceans undergo metamorphosis. This involves a change of appearance, behavior, nutrition source, and shape. Some insects and crustaceans go through complete metamorphosis, while others undergo incomplete metamorphosis.
Most insects and crustaceans go through three or four stages of metamorphosis. The first stage is called an instar. Instars are not fully developed and are typically characterized by pale color and markings. They are vulnerable and unable to reproduce.
The second stage of the insect life cycle is called a pupa. During this phase, the insect’s body is rebuilt. This may be covered by a protective cocoon. As the insect grows, it begins to eat different types of food. It can also be regenerated if it is lost or damaged.
Spiders do not go through an instar stage. Instead, they have three main growth stages. During each of these, the spider sheds its exoskeleton.
The exoskeleton of spiders is made from protein. It is flexible and tough, and helps support the spider’s internal organs. A spider’s legs have seven segments and many bristles.
Several types of hemocytes are found in the spider haemolymph. These include granular and circulating hemocytes. Hemocytes have a copper-based pigment known as hemocyanin. During a molt, hemolymph raises blood pressure, which allows the spider to stretch its legs.
As the spider grows, its blood transports nutrients and hormones. It also lubricates tissues and transports wastes.
Female spiders may lay up to 3,000 eggs in egg sacs. Each of these sacs is spherical and may contain hundreds of eggs. They are usually protected by the female spider until the young emerge.