Kids Research Express

. Gastrotrich, group of microscopic wormlike animals that are common in aquatic environments worldwide. The gastrotrich lives in bottom sediments and on the surface of submerged vegetation and debris. Its head is divided into lobes and its body is generally flat, transparent, and unsegmented. Its back and sides are spiny, bristly, or scaly. The flattened bottom surface bears small hairs, or cilia, in characteristic patterns that are helpful in classifying species. Along the sides of the body are adhesive tubes that are used for clinging to vegetation. Gastrotrichs range in length from 0.05 to 4.0 mm (0.002 to 0.16 in). Marine gastrotrichs, those living in the ocean, are abundant on the surfaces of corals and in shallow sandy areas, while freshwater species prefer standing water such as puddles, marshes, and wet bogs. They may be present in habitats where there is much decay and they can withstand low levels of dissolved oxygen for short periods. The gastrotrich feeds as it moves, inges...

. Ctenophora -> Jellyfish-like marine animals distinguished by eight rows of cilia that propel the body in swimming. They feed on other invertebrates using two retractable sticky tentacles to capture prey. All ctenophores are hermaphroditic and reproduce sexually. Many are luminescent. – Examples: Sea walnuts, comb jellies Platyhelminthes -> Structurally simple worms with no anus or circulatory system. Known as flatworms, their flattened bodies enable internal tissues to be near the skin surface, permitting gas and nutrient exchange with the environment. A muscular layer just beneath the skin layer aids in locomotion. Flatworms are hermaphrodites and reproduce sexually. They typically have a life cycle involving a parasitic larval stage. Many types of flatworms are parasites of vertebrates. – Examples: Flatworms, flukes, tapeworms Mesozoa -> Minute parasitic animals of invertebrates, particularly squids and octopuses. These worms have a simple, elongated, ciliated body. The...