Phylum Echinodermata

Phylum Echinodermata

Consists of animals such as sea stars, sea cucumbers, feather stars, sea lilies, brittle stars, and sea urchins that have 5 part radial symmetry, spiny skin, a water vascular system with tube feet, and an endoskeleton of calcium carbonate plates.

Five part radial symmetry

a form of radial symmetry where an object or organism can be divided into five equal parts arranged around a central point

Water vascular system

A network of fluid-filled tubes that uses water pressure for gas, nutrient, and waste transportation, body movement, and catching food.

Tube feet

Extensions of the water vascular system used for crawling, climbing, holding on, and general movement.

Dermal branchiae

Soft bumps on the body of some echinoderms that function in oxygen exchange.

Pedicellaria

Pincher-like pairs of organs in some echinoderms that protect the animal from parasites and remove debris.

Madreporite

A small opening on the top of the body that regulates the amount of water entering and exiting the water vascular system.

Ampullae

Small sacs along the radial canals of the water vascular system that fill with water and expand, connected to the tube feet.

Class Crinoidea

The class that includes feather stars and sea lilies. 

Cirri

Short, hook-like legs found on feather stars (and along the stalk of some primitive lilies).

Class Asteroidea

The class that includes sea stars.

Class Ophiuroidea

The class that includes brittle stars, which use their longer, slimmer arms and tube feet for faster locomotion.

Class Echinoidea

The class that includes sand dollars and sea urchins.

Test

The hard, solid shell made of calcium carbonate found in sea urchins and sand dollars.

Aristotle’s Lantern

A complex, 5-part jaw apparatus used by sea urchins and sand dollars for grazing, scraping algae, or biting.

Class Holothuroidea

The class that includes sea cucumbers, characterized by an elongated body and the ability to expel internal organs when threatened.