at which stage does a silkworm produce silk thread
Sericulture Silkworm larvae are fed with mulberry leaves, and, after the fourth moult, they climb a twig placed near them and spin their silken cocoons. The silk is a continuous filament comprising fibroin protein, secreted from two salivary glands in the head of each larva, and a gum called sericin, which cements the filaments. The sericin is removed by placing the cocoons in hot water, which frees the silk filaments and readies them for reeling. This is known as the degumming process.[8] The immersion in hot water also kills the silkworm pupa.
Giant tube worm They have a highly vascularized, red "plume" at the tip of their free end which is an organ for exchanging compounds with the environment (e.g., H2S, CO2, O2, etc.). The tube worm does not have many predators. If threatened, the plume may be retracted into the worm's protective tube. The plume provides essential nutrients to bacteria living inside the trophosome. Tube worms have no digestive tract, but the bacteria (which may make up half of a worm's body weight) convert oxygen, hydrogen sulfide, carbon dioxide, etc. into organic molecules on which their host worms feed. This process, known as chemosynthesis, was recognized within the trophosome by Colleen Cavanaugh.[6]