The adults are recognizable by their usually five-point radial symmetry , and include such well-known animals as starfish , sea urchins , sand dollars , and sea cucumbers , as well as the sea lilies or "stone lilies". The phylum contains about living species ,  making it the second-largest grouping of deuterostomes a superphylum , after the chordates which include the vertebrates , such as birds , fishes , mammals , and reptiles. Echinoderms are also the largest phylum that has no freshwater or terrestrial land-based representatives. Aside from the hard-to-classify Arkarua a Precambrian animal with echinoderm-like pentamerous radial symmetry , the first definitive members of the phylum appeared near the start of the Cambrian. One group of Cambrian echinoderms, the cinctans Homalozoa , which are close to the base of the echinoderm origin, have been found to possess external gills used for filter feeding, similar to those possessed by chordates and hemichordates. The echinoderms are important both ecologically and geologically.
What Are the Causes of Rectal Mucus?
Proctitis - Symptoms and causes - Mayo Clinic
A discharge may be the release of any secretion from any surface of the body or the cavities. Sometimes these discharges may arise from much deeper in the body. Different types of discharge may occur for different reasons. Similarly flatus gas is not considered an abnormal rectal discharge.
What Can Cause Mucus in Stool?
Fecal incontinence FI , also known as anal incontinence , or in some forms encopresis , is a lack of control over defecation , leading to involuntary loss of bowel contents—including flatus gas , liquid stool elements and mucus , or solid feces. FI is a sign or a symptom , not a diagnosis. Incontinence can result from different causes and might occur with either constipation or diarrhea. Continence is maintained by several interrelated factors, including the anal sampling mechanism , and usually there is more than one deficiency of these mechanisms for incontinence to develop. The most common causes are thought to be immediate or delayed damage from childbirth , complications from prior anorectal surgery especially involving the anal sphincters or hemorrhoidal vascular cushions , altered bowel habits e.
One way a fistula may form is from an abscess —a pocket of pus in the body. The abscess may be constantly filling with body fluids such as stool or urine, which prevents healing. Eventually, it breaks through to the skin, another body cavity, or an organ, creating a fistula. Fistulas are more common in Crohn's disease than they are in ulcerative colitis.