GENERAL HISTOLOGY

Detailed explanation-1: -Echinoderms have an open circulatory system, and respiration and excretion occur by means of dermal gills, small finger-like projections of the skin that stick out near the base of the spines on the surface. The large coelom also functions in circulation and in respiration.

Detailed explanation-2: -Excretion in echinoderms is by simple diffusion of metabolic wastes (ammonia) across thin permeable regions of the body wall. A variety of gas exchange structures, including the tube feet, is found in various echinoderms.

Detailed explanation-3: -Answer and Explanation: The correct answer is (b). Echinoderms do not have gills.

Detailed explanation-4: -Echinoderms have a unique water vascular system. This network of fluid-filled tubes helps them to breathe, eat, and move. Therefore, they can function without gill slits. Echinoderms also have a very simple digestive system, circulatory system, and nervous system.

Detailed explanation-5: -How Do Echinoderms Breathe? Echinoderms have a simple respiratory system. Depending on the species, they breathe by diffusion through simple gills or projections on their bodies, such as tube feet.