echinoderms
TRANSCRIPT
Echinoderms
“spiny skin”
Echinoderms: Main Characteristics
• Spiny Skin – Exoskeleton – Musculoskeletal
• 5 part radial symmetry – Penta-radial
• Tube feet: Movement– Water-vascular system
• Benthic organisms
Classes
• Asteroidea: Sea Stars• Ophiuroidea: brittle
stars • Echinoidea: sea urchins
and sand dollars • Holothuroidea: Sea
cucumbers • Crinoidea: Sea Lilies and
feather stars
Class Asteroidea: Sea Stars
• Aster = star, oides = in the form of
• Large Coelome• Circulatory system: – use diffusion & cilia to
move gas, nutrients and waste
• Respiratory system: – Dermal branchi on skin
Diagram the arm of the starfish
Asteroidea
• Digestive System: – Mouth on underside– Opens into cardiac
stomach • Folds out of body into prey
to secrete enzymes
– Opens into the pyloric system • Nutrients diffuse out of the
pyloric stomach
• Eat: – mollusks, crustacheans,
polychaetes, coral, detritus
The Water Vascular System
• Who can explain how hydraulics work? • Water Vascular System:– Made up of a series of water-filled canals that run
down the arms from a canal ring in the center • Radial canal – ampullae – tubed feet
Water Vascular System
Asteroidea vs. Ophiuroidea
• Sea Star vs. Brittle Star• Sea Stars: – Arms attached to arms – Carnivores: Active
Predators
• Brittle Star– Arms NOT attached to
arms– Not active predators: eat
plankton
Echinoidea: Sea Urchins
• Same structure, longer spines than starfish – Move by means of tube
feet
• Feeding – Herbivores, feed on algae
and marine plants – Grazers – Scrape food using
ARISTOTLES LANTERN!
• Roles: – Control algae
Sea Cucumbers
• Elongated Body Plan – Long sea urchin
• Tube feet to move • Separate sexes • Take organic nutrients out
of sand – Use oral tentacles
• Defense: – release internal organs– Tubules called cuvierian
tubules: sticky and poisonous
CFU
• What is the etymology of Echinoderm • What is the organ called that extends and
contracts echinoderm’s tube feet? • What kind of symmetry are Echinoderms? • What is a major difference between the feeding
habits of starfish and sea urchins? • What is the major difference between sea stars
and brittle stars • Explain how sea cucumbers defend themselves.
Why are they able to do this?