1. Phylum Echinodermata

2. Echinoderms Sea StarsSea Stars Sea UrchinsSea Urchins Sand DollarsSand Dollars Sea CucumbersSea Cucumbers

3. Echinoderms “Spiny Skin”“Spiny Skin” 7,000 species7,000 species Marine EnvironmentsMarine Environments –Shallow and deep waters Vary in sizeVary in size –From 1cm to 1m (3feet) Often brilliantly coloredOften brilliantly colored

4. Echinoderms Radial SymmetryRadial Symmetry –Like cnidarians and ctenophores Lack cephalizationLack cephalization Larvae are bilaterally symmetricalLarvae are bilaterally symmetrical Sea Star Sea Urchin Brittle Star

5. Echinoderms Echinoderms are deuterostomes, which makes them different from all of the other invertebratesEchinoderms are deuterostomes, which makes them different from all of the other invertebrates Deuterostomes are coelomates whoseDeuterostomes are coelomates whose 1.embryos have radial cleavage 2.anus forms near the blastopore 3.mesoderm arises from outpockets of the endoderm

6. Echinoderms Have: Pentaradial symmetryPentaradial symmetry –the body parts extend from the center along five spokes An endoskeleton composed of calcium carbonate platesAn endoskeleton composed of calcium carbonate plates Many small, movable extensions of the water-vascular system called tube feet, which aid inMany small, movable extensions of the water-vascular system called tube feet, which aid in –Movement –Feeding –Respiration –Excretion

7. Echinoderm Classification CLASSES:CLASSES: –Crinoidea ( kri-NOID-ee-uh ) –Asteroidea ( AS-tuh-ROID-ee-uh ) –Ophiuroidea ( OH-fee-yoor-OID-ee-uh ) –Echinoidea ( EK-uh-NOID-ee-uh ) –Holothuroidea ( HOH-loh-thuh-ROID-ee-uh )

8. Class Crinoidea “lily-like”“lily-like” Examples: sea lilies, feather starsExamples: sea lilies, feather stars –Five arms extend from the body and branch to form many more arms –Tube feet  gas exchange –Cilia on arms direct food to the mouth –Mouth faces up

9. Class Ophiuroidea “snake-tail”“snake-tail” Examples: basket stars and brittle starsExamples: basket stars and brittle stars –Long, narrow arms help them move quickly Can break and regenerate easilyCan break and regenerate easily –Live on the ocean’s floor –Either rake in food with arms or trap it with their tube feet or mucus between their spines

10. Class Echinoidea “spinelike,”“spinelike,” Examples: sea urchins, sand dollarsExamples: sea urchins, sand dollars –Test –compact, rigid endoskeleton –Urchins: Five teeth + their muscles = Aristotle’s LanternFive teeth + their muscles = Aristotle’s Lantern Spines can be sharp and contain venomSpines can be sharp and contain venom –Sand dollars: Burrows into the sandBurrows into the sand Use spines for locomotion and burrowingUse spines for locomotion and burrowing

11. Aristotle’s Lantern

12. Class Holothuroidea “water polyp” Examples: sea cucumbers –Soft bodies because the particles that make up their endoskeleton are small –Use tentacles to bring food to the mouth

13. Sea Cucumbers Eviscerate their gut as a means of self defense

14. Class Asteroidea “starlike” Examples: sea stars –Live in coastal waters around the world –Prey on oysters, clams, and other foods humans eat

15. Structure and Function 24Sea stars typically have 5 arms, but in some species, there may be as many as 24 Two rows of tube feet run along the underside of each arm

16. Structure and Function pedicellariaeOn sea stars and sea urchins, pedicellariae, or little pincers, help keep the body surface free of foreign objects, including algae and small animals that might damage its soft tissues

17. Structure and Function Gas exchange and waste excretion take place by diffusion through the skin gills,Gas exchange and waste excretion take place by diffusion through the skin gills,

18. Structure and Function Primitive nervous systemPrimitive nervous system No head = no brainNo head = no brain The nervous system consists mainly of a nerve ring that circles the mouth and a radial nerve that runs from the nerve ring along the length of each armThe nervous system consists mainly of a nerve ring that circles the mouth and a radial nerve that runs from the nerve ring along the length of each arm Together, they coordinate the movements of the tube feetTogether, they coordinate the movements of the tube feet

19. Structure and Function nerve netSea stars also have a nerve net near the body surface that controls the movements of the spines, pedicellariae, and skin gills. Eyespot on each arm responds to light Tube feet respond to touch and chemicals

20. Water-Vascular System Madreporite Madreporite-water enters through this small pore Stone canal Stone canal -connects madreporite and ring canal Radial canal Radial canal -extends down each arm and carries water to hundreds of hollow tube feet---has valves to ensure one way flow

21. Feeding and Digestion Most echinoderms are carnivores. A sea star captures a clam and attaches to both shells with its tube feet, eventually tiring the clam’s muscles. Once the shell is opened every so slightly, the sea star ejects a portion of its stomach into the clam to digest the tissue. The sea star ejects a portion of its stomach when it feeds. Waste is expelled through anus on aboral surface.

22. Reproduction Most echinoderms are dioecious. Fertilization occurs externally after the organisms spawn. A free-swimming larva called a bipinnaria results and eventually develops into an adult. regenerateAs long as a portion of the central ring remains intact, a sea star can regenerate.

23. Regeneration

25. Which Class? Asteroidea Ophiuroidea Holothuroidea Echinoidea Crinoidea