water vascular system
-network of canals & feet (podia), used for food collection/feeding, locomotion/movement and gas exchange
-A network of water-filled canals unique to echinoderms branching into extensions called tube feet that use hydraulic pressure to extend/retract.
-water is ingested through madreporite and becomes part of the coelomic fluid, fluid in tube feet is sucked in and pushed out
Axial organ/ dorsal sac
-a complex and elongated organ/mass of tissue which covers the stone canal
-found in all echinoderms except holothurians
-function not well understood, but possible functions include: defense against invading organisms, can contract, is responsible for a circulation of fluids, and may have excretory and secretory activity
perivisceral coelom (PVC)
-A coelomic cavity which contains all the innards of a echinoderm
-The extensive body cavity (coelom) is modified to form several specialized regions. Two subdivisions of the coelom are the perivisceral coelom and the water-vascular system.
-The perivisceral coelom is a large, fluid-filled cavity in which the major organs, particularly the digestive tube and sex organs, are suspended.
-aids a little in circulation (along with the WVS and the hemal system)
-modified genital plate that intakes water for WVS
-"mother pore", opening used to filter water into the water vascular system
-the sievelike, disk-shaped opening through which water flows in and out of the water vascular system; helps filter out large particles from entering the body.
-jawed pincer structures used for anti-fouling, defense/protection, even prey capture/feeding
-some are toxic
-sea stars: 2 jaws
-urchins: 3 jaws
-pinchers/forceps, pincerlike appendages used for protection, feeding and cleaning
-strategically positioned to guard the papulae, trapping any organism that might
attempt to eat the papula or gain access to the starfish through these thin-walled soft and
-A channel along the oral surface of each arm through which rows of tube feet protrude
-The ambulacral grooves are supported by a definite arrangement of ossicles: two rows of rod-shaped ambulacral ossicles
-The starfish ambulacral groove are its microscopical parts. These can be the suckers, spines or plates.
-the center of the starfish nervous system that encircles the mouth
-the nervous system of echinoderms, a nerve ring of nervous tissue and 5 radial nerves;
-a ring of concentrated nervous tissue about the pharynx
-surrounds the mouth and helps to coordinate their movements and responses
-this gives off five sensory radial nerve cords which travel the length of each arm
-A structure which runs the length of each arm and takes water out to the arm from the ring canal
-channel-like extensions through the mesoglea that transport nutrients and waste, extends from the ring canal and into the starfish's arms-runs the length of the arm, is part of the water vascular system
-the main pump for the starfish, water gets distributed from here. The mouth is in the dead center of it on the other side.
-Suction-cuplike structure attached to radial canals of echinoderms; used to walk and to open shells
-tentacular tubular process of most echinoderms, having a sucker at the end and used for e.g. locomotion and respiration
-hollow cylinders tipped with a powerful sucker
-characteristic of the water vascular system
hemal (hyponeural) canal
-small, ciliated projections of the body wall, serving for respiration and excretion
-pseudo gills, allows for gas exchange between PVC and outside
-sac-like vesicles between ossicles that protrude from the external surface of the starfish.
-fluid-filled interiors are continuous with the coelom
buccal tube foot
-teeth and jaws of sea urchins; consists of 40+ ossicles, including 5 teeth on interambulacral region; held in place by muscular attachments that also move the jaws; provides very strong biting power, enabling urchins to each tough vegetation. surrounded by gills, hardest working structure in sea urchins
-embeddle fused endo-skeleton
-shell of sea urchins, a hard test composed of fused plates of calcium carbonate covered by a thin dermis and epidermis. The test is rigid, and divides into five ambulacral grooves separated by five interambulacral areas. Each of these areas consists of two rows of plates, so the test includes 20 rows in total. The plates are covered in rounded tubercles, to which the spines are attached. The inner surface of the test is lined by peritoneum
(Echinodermata, Class Holothuroidea)
-fundamentally modified sea urchins
-lack ossicles and spines in body wall (but have ring of ossicles around esophagus, analogous to aristotle's lantern), they do have calcareous spicules
-defense strategies: chemically defended and cryptic
-larger cukes have greatly expanded hemal system (used as circulatory system)
Closed ambulacral system
Open ambulacral system