Echinoderms Sea Stars, Sea Urchins, Sand Dollars, Sea Cucumbers Kingdom Animalia, Phylum Echinoderms Greek: Echinos = “spiney”; dermos = “skin”

Types of Echinoderms They lack body segmentation. There are more than 6000 species.

Penta-Radial Symmetry in adults. Bilateral Symmetry in larva. Penta means: ______________

Made of calcium carbonate plates and spines called a “test”

Water-vascular System A system of fluid-filled tubes that work together to enable echinoderms to move, get food, and circulate. Tube foot: small, muscular fluid filled tubes that end in suction-cuplike structures. Three essential body functions. 1) Respiration 2) Movement 3) Digestion

Movement: Living suction cups, muscles that pull up the center of the cup causing suction. Many feet working together exert force allowing it to “walk” and attack.

Feeding and Digestion Use tube feet (living suction cups) Many sea stars push their stomach out of their mounts and onto the prey, they then spread digestive enzymes over the food to bring into the mouth. Sea urchins use beak-like plates to scape off algae. Others extend arms and trap food.

Respiration Diffusion Some use tube feet to diffuse oxygen into the body. Some use thin-skinned gills. Sea cucumbers have branched tubes.

Response Nerve Ring that surrounds mouth with branching nerve Nerve Cord connecting to other body parts.

Reproduction + Development Sexual Females shed eggs and males shed sperm for external fertilization. Fertilized eggs turn into free swimming larvae.

Echinoderm Diversity

Sea Star Anatomy

Sea Urchins Sea Urchins look like big pin cushions. They use these spines for protection against predators. The spines also act like stilts to keep their bodies up off the ground so the tube feet can pull them around! They eat mostly algae. They live mostly attached to rocky crevices, which protect them from waves and tide surges. They have become a popular item to eat and are being harvested in alarming numbers.

Sand Dollars Are found on the sandy shore or muddy bottoms. They feed standing on edge with their tube feet acting as filters. The star pattern seen on top of the sand dollars is actually caused by special breathing tube feet! The mouth is found on the under side of the animal.

Sea Cucumbers Sea cucumbers have tentacles at their mouth openings to grab and hold food. Radial symmetry and spiny bodies like all other echinoderms. When provoked, or annoyed, Sea cucumbers throw out their intestines to entangle, frighten, or confuse their predator. Then the intestines are regenerated. They are filter feeders. Sea Cucumbers are considered a delicacy in Asian cultures.