Phylum Echinodermata (Means spiny skin)

Echinodermata Classes Sea stars Asteriodea(Stelleroids) Aka starfish

Echinodermata Classes Crinoidea/Crinoids Feather stars Sea lilies

Echinodermata Classes Compact body within a shell Echinoidea/Echinoids Sea urchins, sand dollars No arms, often spiny

Echinodermata Classes Elongated body Holothuroidea (Holothuriods) Sea cucumbers Leathery body wall with embedded ossicles (bony plates)

Ophiunoidea Brittle stars, Basket stars (Add this to your hand out!)

Echinodermata Common Characteristics as opposed to bilateral Radial Symmetry Like spokes on a wheel

Echinodermata Common Characteristics Or Cylindrical Body may be round With 5 or more ambulacra (radiating areas) Or star shaped

Echinodermata Common Characteristics Can regenerate lost parts Endoskeleton with spines or spicules

Echinodermata Common Characteristics Simple Nervous system No head or brain No excretory organs Few specialized sensory organs Nerve ring / radial nerves

Echinodermata Common Characteristics Water Vascular System Water is taken in at the madreporite Helps with respiration, Circulation and movement

Specialized structures… Mouth and anus – ingestion and excretion of digestive wastes Madreporite – sieve like structure through which water is taken in. Some species - gills

Tube feet for movement Gonads - make gametes (sperm and eggs)

Echinodermata Anatomy

Echinodermata Reproduction Or gonochoric (two distinct sexes) May be hermaphrodites Usually release sperm / egg into the water column External fertilization Many species synchronize this, along the lunar cycle

Echinodermata Nutrition They have specialized mouthparts for this Most sea urchins scrape algae off surfaces Called Aristotle’s lantern A few are scavengers or predators

Echinodermata Nutrition Some are active filter feeders Brittle stars are mostly scavengers Or just lay about waiting for food to float by and stick to them They crawl about on the bottom looking for dead stuff

Echinodermata Nutrition They tear open mollusks with their arms Sea stars are carnivores Then extrude their own stomach out of their mouths to release digestive juices into the clam’s body.

They eat mollusks like clams and mussels, some eat coral (‘Crown of thorns’) Answer to #6 on the hand out