GENERAL HISTOLOGY

Detailed explanation-1: -They have tube feet on their underside, like sea stars, but the feet do not have suction cups at the end and are not used for locomotion-they are used for feeding and to help the brittle star sense its environment.

Detailed explanation-2: -They move fairly rapidly, because they do not depend on tube feet as does their sister group the sea stars. Instead, brittle stars use their arms to quickly propel themselves along the seafloor. This species’ arms reach up to 60 cm.

Detailed explanation-3: -Brittle stars are characterized by five long, slender limbs fixed onto a central body disk (a phenomenon known as pentaradial symmetry). A species can develop arms that are almost eight inches in length (20 cm) and a disk that is about an inch (2.5 cm) in diameter.

Detailed explanation-4: -They do not, like sea stars, depend on tube feet, which are mere sensory tentacles without suction. Brittle stars move fairly rapidly by wriggling their arms which are highly flexible and enable the animals to make either snake-like or rowing movements.

Detailed explanation-5: -Each brittle star has a distinct central disk and five skinny, flexible arms. The central disk is made up of a skeleton of calcium carbonate and contains all the internal organs. Brittle stars’ arms twist and coil to help them move across the seafloor.