Kids Research Express

. Peanut Worm, common name for small, unsegmented marine worms having bulb-shaped bodies and bearing crowns of tentacles on long, slender, processes, called introverts, that can turn inside out. Peanut worms are common but inconspicuous, frequently nestling among shells; they can burrow, but they move slowly. The main part of the body contains a single cavity (the coelom) filled with fluid under pressure from the body musculature. When the introvert turns inside out, the tentacles at its tip are used for feeding on small particles of organic matter. The placement of peanut worms in the animal kingdom is uncertain, but they are probably close to the annelid worms. Little structural diversity exists within the group; about 250 species have been described. Scientific classification: Peanut worms make up the phylum Sipuncula.

. Annelida -> Segmented worms with a muscular body wall used for burrowing. External hairs called setae aid in traction during burrowing. An internal coelom is divided into compartments by walls known as septum. The digestive system stretches from the mouth to the anus, differentiated into regions, each with a different function. Reproduction is sexual. – Examples: Lugworms, earthworms, leeches Pogonophora -> Deep-sea worms that live in chitinous tubes attached to the ocean floor. Their long, slender body has a beard of tentacles at the head end. There is no mouth or digestive system and these animals absorb all nourishment through the body surface. They reproduce sexually. – Examples: Bead worms Vestimentifera -> Giant deep-sea worms that live in chitinous tubes attached to the ocean floor. They derive nutrition using a specialized organ called a trophosome to digest sulfide-oxidizing bacteria. – Examples: Llamellibrachs Sipuncula -> Marine worms with a saclike body an...