The ossicles can be long and sharp-as you see in sea urchins- or short and hair-like as seen on sand dollars and their relatives). In sea urchins (which includes sand dollars), ossicles are tightly fused into sphere or flattened cake-like shapes with articulated, projecting spines. Ossicles come in many shapes, which creates the diversity of complicated body types observed in echinoderms. Similar to a complicated 3-D puzzle, these pieces are infused with tissue and covered by an epidermis, or skin like covering. Sea lilies, however, obtain water through many pores that cover their body.Įchinoderms possess a unique internal skeleton (or endoskeleton) composed of thousands to millions of calcium carbonate components known as ossicles. In most echinoderms, water enters the body through the tube foot grooves and via a plate called the madreporite, which is often visible to the naked eye on the top side of sea stars. This system uses water pressure to help give the animal shape and help them travel. While humans rely on a network of vessels filled with blood, echinoderms possess a complicated series of tubes which uses seawater to convey nutrients and gases throughout their body. The ochre sea star ( Pisaster ochraceus) exhibits the classic five-fold symmetry.Īnother characteristic of all echinoderms is their water vascular system.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |