Phylum Echinodermata The Spiny Skin Animals Examples: Sea Stars Brittle Stars Sea Urchins Sea Cucumbers Sea Lilies Feather Stars

Pentamerous radial symmetry Body is arranged around a central axis in 5 parts

Solaster

Water Vascular System Unique organ system that water-filled tube and water pressure for both locomotion and feeding. System of tubes end in tube feet.

Endoskeleton Consists of plates calcium carbonate (CaCO3). Plates are often studded with spine, hence their name. Typically divisible in 5 parts

Bottom Dwellers Benthic Most abundant on rocky shores Can be found in every ocean, at all depths

Class Asteroidea: Sea Stars Found from subtidal to deepest part of ocean Five appendages (arms) radiating from a central axis Eat mussels and are considered pests by seafood industry Examples: Bat Star (Pateria)- W. Coast, Kelp beds Sun star (Solaster)- 10 –15 arms, eat other sea stars

Respiration Skin Gills- ciliated finger-like projections on the dorsal surface of the skin Breathe through their skin and tube feet Coelom- fluid filled sac lined with cilia that beat and circulate water. Diffuse O2, CO2, and wastes

Feeding and Locomotion Arms are used for locomotion and getting food. Carried out by the Water Vascular System Water enters the madreporite (sieve plate) stone canal Ring Canal Radial Canal Tube feet Tube feet are delicate projections attached along the side of the radial canal in a groove

Feeding and Locomotion Ampulla- top of the tube foot, resembles a medicine dropper. Feet suction to surfaces. Allows sea stars to attach to bivalves and pull open shells by tugging for hours therefore weakening the adductor muscles. Sea star pushes its stomach out through the mouth and digests the food externally.

Response Eyespots- tiny light receptors located at the end of each arm (orange in the picture). Light is converted into electrical impulses that are carried to central nerve ring around the mouth which then directs the arms.

Reproduction Sexually Gonads are located inside each arm near the central disk. Fertilization and development occur externally In the picture are different phases of new organisms from single-celled organisms to larva.

Regeneration Sea stars can regenerate new arms if cut off A new Sea Star can grow from an arm as long as part of the central disk is present. In the photo a Northern Sea Star is regenerating two arms. It will take over a year!

Johnathan Bird Sea Stars

Class Echinoidea Sea Urchins and Sand Dollars Oval or round bodies; lack arms; use spines and tube feet to move; eat algae off rocks using Aristotle’s Lantern (5-toothed mouth structure)

Aristotle’s lantern

Protection and Predation Use spines to wedge themselves into spaces between rocks; protects from wave action and predators (except California Sea Otter!)

Reproduction Similar to sea star Used for embryological studies because of blastula phase of urchin.

Sand Dollars and Sea Biscuits Sand Dollar: short spines cover its skin; burrow in sand and feed on plankton. Sea Biscuits: more rounded body; longer spines; lives around coral reefs.

Class Ophiuroidea Brittle Stars Solitary, nocturnal creatures that hide under rocks during the day. Found in intertidal zone to the deep; from tropics to Arctic Use long muscles in long, skinny arms in order to scurry rapidly about on the sea floor. Can detach appendages when attacked. Brittle stars on a sea cucumber.

Class Crinoidea Sea lilies and Sea Feathers Most ancient of echinoderms Have feathery appendages to catch food (plankton) Limited movement. Sea lilies are sessile; Sea feathers slowly crawl on coral reefs.

Class Holothuroidea Sea Cucumbers Soft, oblong body w/no arms; tube feet arranged in five rows; no endoskeleton or spines; only have small bony pieces in the skin Use sticky branching tentacles (enlarged tube feet) to trap microscopic organisms. Extend around mouth during feeding and retracted when disturbed. No skin gills- take in and release water thru anus and gas exchange occurs in the coelom across membranes call the “respiratory tree” If attacked, SC will release its digestive organs to leave a meal for the predator and escape.

Sea Cucumbers examples

Arthropoda and Ecinodermata Specimen Lab Number a piece of paper #1-13, leaving a line in between. Write the question and answer. Underline you answer. Turn in to me when finished. You need your Arthropod and Ecinoderm notes.

Sea Star Pre-lab Label the starfish in your notes. Color the digestive organs red. Color the water vascular system light blue. Color the reproductive glands purple. Color the skin orange. Color the madreporite dark blue. Eyespot Endoskeletal plates Anus Stomach Madreporite Reproductive glands Tube foot Sucker Ring canal Radial canal Digestive glands