Kids Research Express

. 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...

Tardigrade Tardigrade, any of a group of tiny arthropod -like animals characterized by four pairs of stubby legs ending in large claws, a stout body, rounded back, and lumbering gait. They are also known as “water bears.” Tardigrades live worldwide in moist land habitats, along rocky shorelines, and on the bottoms of streams, lakes, and oceans. Their most striking feature is their ability to temporarily enter a nearly lifeless state known as anabiosis, which helps them survive environmental extremes. About 400 species of tardigrades are known and they range in length from 0.1 to 0.5 mm (0.004 to 0.02 in). Tardigrades are most commonly found in association with the water film on mosses, liverworts, and lichens. Their densities may reach 2 million individuals per sq m (185,874 per sq ft) of moss. Some live in hot springs and a few live in a symbiotic relationship with or on the bodies of other animals. Tardigrades use a pair of oral stylets, or needle-like mouthparts, to pierce the walls...