phylum echinodermata: sand dollars, starfish, and sea urchins

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Phylum Echinodermata: Sand Dollars, Starfish, and Sea Urchins. By: Amanda Brainerd. Key Characteristics . Endoskeleton Five-part radial symmetry Water-vascular system Skin Gills No head or brain. Anatomy. Sieve Ring canal Tube feet Anus Stomach Digestive glands Skin gills - PowerPoint PPT Presentation


Phylum Echinodermata: Sand Dollars, Starfish, and Sea Urchins

Phylum Echinodermata: Sand Dollars, Starfish, and Sea UrchinsBy: Amanda Brainerd

Endoskeleton Five-part radial symmetryWater-vascular system Skin GillsNo head or brainKey Characteristics

Endoskeleton:, they have a ossicles which is a calcium rich endoskeleton Five-part radial symmetry: most adults have five arms sticking from a central pointWater-vascular system: a water-filled system of interconnected canals and thousands of tiny hollow tube feet, it functions in feeding and gas exchange. Skin Gills: assist in respiration and waste removal No head or brain: echinoderms have only specialized sensory organs. 2AnatomySieve Ring canalTube feetAnusStomachDigestive glandsSkin gillsReproductive glands

Sieve: wire like frame that makes the structureRing canal: connected to all the nerves and spread messages throughout bodyTube feet:Anus: where wastes are exretactedStomach: where food is digestedDigestive glands: in stomachSkin gills: help with breathing:Reproductive glands: whether it is a male or female it have reproduction capabilities. 3Simple digestionIn through mouth and down esophagusTwo-stomach system IntestinesAnus


A simple digestion process for the starfish for example, the food goes in through the mouth and down the esophagus into the first stomach the cardiac stomach and then goes to the pyloric stomach were it is digested. Then it goes into the intestines and digestion glands and then out through the anus. 4Water vascular system Tube FeetSkin GillsBumps or Spines on surfaceHemolymphCirculation


1. Makes the exchange between oxygen and carbon dioxide.2. are the gills where oxygen enters and carbon dioxide exits the body. 22223. Absorb oxygen out of the body and take CO2 out of the body. 3. are used to take in oxygen as well4. is the blood in the body that circulates through the body5. also uses the water vascular system to circulate the hemolymph through the system. 5Water vascular system Madreporite Ring CanalWaterTube Feet

Internal Transport

internal network of fluid-filled canals that connect to the tube feetis an entry way of seawater into the water vascular system is connected to the madreporite and five canals through the finger like body segments.Goes in and out through the madreporite and runs through the ring canal and through the radial canals to provide circulation to all of the body. Water is also propelled in and out of the feet like suction cups

6AnusMouthTube feet and skin gillsNo real excretion systemDiffusion


-- echinoderms use the anus to get ride of body wastes.Some of the echinoderms dont have the need for an anus so the wastes just go out the mouthWastes also leave through the tube feet and skin gills by diffusion.They have no real excretiotory systemThey use diffusion to get rid of excess nitrogen gas which is normally ammonia gas

7EyespotsNervesTube FeetSpiny SkinStatocysts Response

They have eyespots that at the end of each arm that detect light or darkDont have brains but they have nerves that run from the middle to each armSome have tube feet that are senstive to chemicals and help them find source of smellsThey have spiny skin that is a defense mechanism to fight off predatorsStatocysts are used to tell if the animal is up right or upside down

8Tube and thin layers of musclesTube feetWater vascular systemSuckers and armsSpines Movement

Latched on to plates of the endoskeleton that allow movementBy expanding and contracting certain chambers in the water vascular system, it moves into certain feet and allows the muscle to extend and makes certain feet contract. This allows walking to occurThe suction cups on their arms called suckers, allow them to navigate over rocks in the shallow water.

Some other echinoderms like sea urchins use their spines to allow them to move.

9Diecious Sexual ReproductionExternal fertilizationFission and regenerationLarvae settle on ocean floorReproduction

They are diecious meaning that there are both male and female. Sexual reproduction is the most common way of reproduction by spermatozoa but asexual does happen in asteroids and holothurians where sexual reproduction isnt possible. which involved the fertilization of a egg through external fertilizationFission is common in most species in the phylum Echinoderm but they do have regeneration abilities so If a body part is broken or cut off the animal can reproduce it Larvae go through two stages and then settle on the ocean floor


Echinodermata has approximately 7000 described living species and about 13,000 extinct species known from the fossil record.Brittle Stars can be found at depths as great as 6000 meters.Sea stars have up to 200 light sensitive eye spots.Some species can live up to 10 years. Echinoderms are the most complex of invertebrates.

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