![]() ![]() The madreporite is comparable to the drain of a sink, as it serves as the entry for water into the stone canal, which joins the ring canal, off which radiate the tubes that run down the starfish ’s arms and branch off into the tube feet. This hydraulic system has as its starting point a small reddish spot on the of the central disk, the madreporite. Each tube foot ends in a suction cup, and is the terminal point of an elaborate hydraulic system within the animal. The underside of each arm is lined with hundreds of tiny tube feet. As it moves it does not pinwheel, but follows one arm. The starfish then sets off to catch its prey, slowly and deliberately, at the Chemoreceptors on the starfish ’s skin can detect the faintest smell of its prey (clams), and even determine the direction from which it is coming. The sense of smell, however, is quite sensitive. Starfish can tell light from dark, but are unlikely to see much more than that. The eyes of starfish are extremely simple, are located at the tip of each arm, and are primarily light-sensing dots. There is no central ganglion, but this rather simple arrangement effectively allows the starfish to move (including the ability to right itself should it be turned over) and sense the world around it. ![]() The nervous system of starfish consists of three main networks: the ectoneural (oral), the hyponeural (deep oral), and the entoneuoral (aboral) systems. The skin of starfish is thick with bony plates (ossicles), spines, tiny pincers on stalks (the pedicillerae which keep the animal ’s skin clean of debris), and bumps, between which are tiny folds of skin which function as the starfish ’s gills. Starfish are radially symmetrical with from 5 to 50 arms radiating from a central disk. Starfish come in a rainbow of colors including bright red, cobalt blue, yellows, and the familiar orange-brown. Some species grow up to 3 ft (1 m) in diameter others are barely 0.5 in (1.3 cm) across. Starfish belong to the class Asteroidea, which includes about 1,600 species inhabiting the shallow margins of all of the world ’s oceans. Starfish or sea stars are marine invertebrates in the phylum Echinodermata, which also includes sea urchins, brittle stars, sea lilies, and sea cucumbers. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |