1. Echinoderms and Invertebrate Chordates
Chapter 38 P
Chapter 38 Echinoderms and invertebrate chordates

2. Objective 38.1
Discuss four distinguishing characteristics of echinoderms.
Describe representative species from each of the five classes of echinoderms
Describe the water-vascular system and other major body systems of echinoderms
Compare sexual and asexual reproduction in sea stars
Chapter 38 Echinoderms and invertebrate chordates

3. P. Echinodermata – spiny skin
Is a group of invertebrates that includes sea stars, sand dollars, sea urchins, and sea cucumbers. The members of this phylum, call echinoderms, inhabit marine environments ranging from shallow coastal waters to ocean trenches more than 10,000 m deep. They vary in diameter from 1cm to 1m and are brilliantly colored
Chapter 38 Echinoderms and invertebrate chordates

4. Characteristics Radially symmetrical Have no head or cephalization
Larvae (bilaterally symmetrical)
Fossil records- Cambrian period (500 million years ago
Early were sessile as evolved motile (crawling), 80speices still sessile
Deuterostomes
Coelomates
Chapter 38 Echinoderms and invertebrate chordates

5. Characteristics 4 major not shared by any other phylm
Pentaradial symmetry (center with spokes)
Endoskeleton composed of calcium carbonate plates known as ossicles
Water-vascular system- canals
Tube feet- aide in motion, feeding, respiration and excretion
Chapter 38 Echinoderms and invertebrate chordates

6. Classification 7000 species into 6 classes Crinoidea Ophiuroidea
Echinoidea
Holothuroidea
Asteroidea
(we wont talk about)
Chapter 38 Echinoderms and invertebrate chordates

7. C. Crinoidea – lily-like
Crinoids
Sea lilies, feather stars
Sessile as adults (sea lilies)
Swim crawl as adults (feather stars)
5 arm extension, branch to form many arms- up to 200 in some
Mucus covered tube feet (gas exchange and feeding)
Mouth faces up (most other it is down)
Chapter 38 Echinoderms and invertebrate chordates

8. C. Ophiuroidea- snake tail
2000 species of basket stars and brittle stars
Largest class
Long narrow arms, ability to move quickly
Arms can break easy- regenerate
Bottom of ocean
Chapter 38 Echinoderms and invertebrate chordates

9. C. Echinoidea- spine like
900 species
Sea urchins and sand dollars
Internal organs are enclosed w/in a fused, rigid endoskeleton called a test
Sea urchins
Move by tube feet
Eat algae off surfaces
Aristotle's lantern- teeth and mouth, complex jaw
Some spines contain poison
sand dollars
Live along coast lines, found in sandy areas
Flat round shape
Shallow burrowing
Chapter 38 Echinoderms and invertebrate chordates

10. c. Holothuroidea- water polyp
Sea cucumbers
Armless echinoderms
Live on bottom of sea
crawl or burrow with tube feet
Ossicles make up endoskeleton
Soft bodies
Chapter 38 Echinoderms and invertebrate chordates

11. C. Asteroidea- star like
Sea star, starfish
Live in coastal waters
Variety of colors and shapes
economically important because they feed on oysters, clams (human food)
Chapter 38 Echinoderms and invertebrate chordates

12. C. Asteroidea- External structure-
composed of several arms (5- 24)
Two rows of tube feet under each arm
Body is flattened
Oral surface- mouth side, under side
Aboral surface – opposite to mouth side
Covered with short spines
Tiny pincers called pedicellariae, keep it free from of foreign objects
Chapter 38 Echinoderms and invertebrate chordates

13. C. Asteroidea- Water-Vascular System-
Net work of water-filled canals that are connected to the tube feet
Water enters through pores in the madreporite (sieve-like plate on aboral surface)
Water passes down the stone canal- tube that connects the madreporite to the ring canal (encircles the mouth)
Radial canal carries water to the tube feet (valves keep it from flowing back up)
Ampulla- sacs on feet contract forcing water into the feet
Chapter 38 Echinoderms and invertebrate chordates

14. C. Asteroidea- Feeding and digestion
a. mouth short esophagus cardiac stomach ( can turn inside out through its mouth when it feeds) pyloric stomach (connects to a pair of digestive glands in each arm) nutrients are absorbed into the coelom by walls of digestive cavity and excess is excreted by anus on aboral surface
b. they are carnivores, mollusks, worms
Chapter 38 Echinoderms and invertebrate chordates

15. C. Asteroidea- Other body systems
a. no circulatory, excretory or respiratory organs
b. gas exchange and waste excretion by diffusion in walls of tube feet and skin gills
c. no head and no brain
d. have a nerve ring and radial nerves
e. nerve net and touch-sensitive cells
Chapter 38 Echinoderms and invertebrate chordates

16. C. Asteroidea- Reproduction and development
a. separate sexes
b. each arm has a pair of ovaries or testes
c. 200 million eggs in one year
d. external fertilization-
e. fee-swimming larva bipinnaria
f. 2 months metamorphosis
g. regenerate arms, long time
Chapter 38 Echinoderms and invertebrate chordates

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