(Sea Stars, Sea Urchins, Sand Dollars, Sea Cucumbers) Echinoderms (Sea Stars, Sea Urchins, Sand Dollars, Sea Cucumbers)

General Stuff Echinoderms belong to the Phylum Echinodermata, meaning “hedgehog skin”. Echinoderms have spiny skins. They have radial symmetry. They lack body segmentation. There are more than 5000 species of Echinoderms. Types are sea stars, sea urchins, sea cucumbers, sand dollars.

Types of Echinoderms

Sea Stars- Starfish Have radial symmetry. Most starfish have 5 “arms”or rays. Starfish have tube feet for locomotion, and strong suction to hold them in place. They also have a water vascular system that enables them to store water in their tube feet so they can survive while the tide is out. They breathe through small gills in their skin. Their mouths are located on the underside of their bodies. Starfish can regenerate. (must have the central disc attached).

More Starfish Stuff Sea Stars are carnivorous, yup, they eat mostly shellfish, snails, and barnacles. They use their tube feet to pry open the shells and then throw their own stomachs out into the shell to digest the meat before it’s brought back into its body! There are lots of different types of Sea Stars, about 2000 different kinds. Most Sea Stars have spiny skin.

Sea Star Anatomy

STARFISH LATIN meaning ANIMALIA ASTEROIDEA “star-like” KINGDOM _____________ PHYLUM _____________________________ CLASS _______________________________ ANIMALIA ECHINODERMATA “spiny skin” ASTEROIDEA “star-like”

Starfish (sea stars) Come in a variety of colors http://www.trinitykids.org/Portals/2/graphics/starfish.jpg http://www.perspective.com/nature/animalia/starfish.html http://www.deepseaimages.com/dsilibrary/data/1143/706-28a.jpg

. . . and sizes http://bcuniversal.com/familyimages/Natasha%20&%20Starfish%20Seattle%202000.JPG

Not all starfish have 5 arms http://www.perspective.com/nature/animalia/starfish.html http://www.seashells.org/identcatagories/starfish.htm

SYMMETRY ADULTS- Radial LARVA- Bilateral http://www.uic.edu/classes/bios/bios100/labs/radial.jpg

ORAL VIEW http://wwwbio200.nsm.buffalo.edu/labs/tutor/Starfish/Starfish02D.html

http://wwwbio200.nsm.buffalo.edu/labs/tutor/Starfish

SPINY SKIN SPINES for protection connect to http://wwwbio200.nsm.buffalo.edu/labs/tutor/Starfish SPINES for protection connect to ENDOSKELETON inside underneath skin

OSSICLES Calcium carbonate plates form endoskeleton inside http://ebiomedia.com/prod/BOechinoderms.html

Skin gills between spines http://wwwbio200.nsm.buffalo.edu/labs/tutor/Starfish EXCHANGE GASES and EXCRETE NITROGEN WASTE

TUBE FEET surfaces Can exchange gases and excrete nitrogen waste http://wwwbio200.nsm.buffalo.edu/labs/tutor/Starfish Can exchange gases and excrete nitrogen waste

EYESPOTS Sense light/dark

Madreporite Opening to water vascular system http://ebiomedia.com/gall/skin/skin1.html

TUBE FEET Used for feeding & locomotion http://www.scsc.k12.ar.us/2001Outwest/PacificNaturalHistory/Projects/ReynoldsJ/starfish.jpg

DIGESTIVE GLAND Makes BILE ABSORBS NUTRIENTS

http://www.k-state.edu/organismic/echinoderms_and_protochordates.htm

2 part STOMACH

DIGESTIVE SYSTEM ANUS DIGESTIVE DIGESTIVE GLANDS GLANDS MOUTH Image by Riedell

Saona Island

London Museum

How Starfish Eat

Dancing With the Stars!

Ability to self amputate AUTOTOMY ASEXUAL REPRODUCTION Ability to self amputate AUTOTOMY Ability to regrow lost parts REGENERATION http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/R/Regeneration.html

Spawning Starfish reproduce sexually by spawning. Spawning means that the sex cells are released into the water. Starfish gather in groups to reproduce, which increases the likelihood the sperm and eggs will find each other. Starfish have sexual organs, or gonads, in each arm. During a breeding season the males' gonads fill with sperm and the females' gonads fill with eggs. When starfish spawn, the males release sperm and the females release eggs in great numbers. Female starfish may release millions of tiny eggs into the water during a spawning session.

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.

Sea Urchin Anatomy

Mating Most sea-urchin species have separate sexes and release their gametes into the sea at breeding time in the spring. There are 5 gonads communicating with the outside via 5 gonopores visible, as shown here, as 5 holes in the test. The gonads are discrete and easily accessible, leading to many studies on seasonal cycling of growth, maturation, and spawning.

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.

Sand Dollar Anatomy

Sea Cucumbers Sea cucumbers have tentacles at their mouth openings to grab and hold food. They look like snails, but have 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 and have a sticky slime that covers their tentacles and lets them grab particles from the ocean floor. Sea Cucumbers are considered a delicacy in Asian cultures.

Mating Sea Cucumbers have a very interesting way of mating. They are not in the least bit intimate and it involves little to no interaction with the other Sea Cucumbers. What they do is that the males just release sperm into the water and the females just release their eggs into the water. It is basically all luck on whether or not the organisms are close to other organisms during mating. Each organism can release thousands of gametes at a time, for females up to 130,000 eggs at a time, which are hopefully fertilized in the water (external fertilization) and become larvae. The Sea Cucumber becomes sexually mature at around year two of an eight year life span. There is no exact number of chromosomes that I can put down for the Sea Cucumber as the results of various studies came back with varying results for some odd reason

Interesting Stuff Some Sea cucumbers are quite poisonous, and the poison has been used as an inhibitor of Cancer growth. Sea Cucumbers secrete a sticky glue as a defense mechanism that has been used as a bandage to bind wounds. Sea Cucumbers will stick each tentacle in their mouths, lick them off and then do the same with the next one- kind of like you licking your fingers after eating!

Sea Cucumber Anatomy