Starfish to starfish by the French zoologist de Blainville in 1830. It is derived from the Greek "aster", ἀστήρ (a star) and the Greek "eidos", εἶδος (form, likeness, appearance). The class Asteroidea belongs to the phylum Echinodermata. As well as the starfish, the echinoderms include sea urchins, sand dollars, brittle and basket stars, sea cucumbers and crinoids. The larvae of echinoderms have bilateral symmetry, but during metamorphosis this is replaced with radial symmetry, typically pentameric. Adult echinoderms are characterized by having a water vascular system with external tube feet and a calcareous endoskeleton consisting of ossicles connected by a mesh of
Cairo spiny mouse Red List of Threatened Species, lists it as being of "Least Concern". A recent study, still under peer review at the time of writing, indicates that this species could become a candidate animal model for the human menstrual cycle. It exhibits a 9-day cycle, and is the first rodent found to have such a cycle. Gene sequencing is currently underway to investigate this, and other unique physiological traits displayed by this species. Cairo spiny mouse The Cairo spiny mouse ("Acomys cahirinus"), also known as the common spiny mouse, Egyptian spiny mouse, or Arabian spiny mouse, is a nocturnal species of