Title
Chapter Title: Echinodermata
Book Title: Invertebrate Histology
Author(s)
Newton, Alisa L.;Dennis, Michelle M.
Published
2021
Abstract
Most members of Echinodermata are dioecious and undergo sexual reproduction, with a few species reproducing asexually. Uniting features of all echinoderms include radial symmetry (pentamerous symmetry), a tricoelomate body cavity, and a body wall composed of calcite endoskeletal plates (dermal ossicles) connected by “mutable collagenous tissue.” The basic echinoderm body plan has 10 divisions: five radii (rays or arms) which alternate with five interradii (interrays). Histologic features of echinoderm organ systems are described in this chapter. Histologically, the echinoid digestive tract has layers similar to other echinoderms. Echinoderms have limited anaerobic capacity and are very sensitive to oxygen availability. The water vascular system is a hydraulic system used for substrate adhesion, locomotion, and in some echinoderms prey manipulation. In most echinoderms nitrogen excretion is primarily in the form of ammonia, which can diffuse across thin portions of the body wall at the papulae and tube feet.
Keywords
echinoderm organ systems;Echinodermata;Histologic feature;nitrogen excretion;water vascular system
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PUB25752