Phylum Echinodermata ECHINODERMS!

Class Crinoidea Special Characteristics: Mouth Faces Upward and is surrounded by many arms – 600 species –Species include- Sea Lilies and Feather Stars Florometra serratissima

Class Asteroidea Body usually has five arms and double rows of tube feet on each arm Mouth faces downward 1,500 Species Ex. Sea Star Six-Rayed Starfish Leptasterias hexactis

Class Ophiuroidea Usually has five slender and delicate arms or rays 2,000 Species Ex. Brittle Stars and Basket Stars Daisy Brittle Star-- Ophiopholis aculeata

Class Echinoidea Body is Spherical, oval, or disck shaped Arms lacking but five part body plan is still seen 900 Species Ex. Sea Urchins and Sand Dollars Centrostephanus rodgersii

Class Holothuroidea Elongated, thickened body Tentacles around Mouth 1,500 Species Ex. Sea Cucumbers Thelenota rubralineata

Evolution Echinoderms first evolved from a single-celled organism Popular Belief that Echinoderms evolved from ancestors which lived in the Pre-Cambrian and Cambrian Periods –Supported by a fossils paleontologists found that they believe was a pre-echinoderm ancestor in the Pre- Cambrian period –Other echinoderms resemble fossils of the Cambrian Period as well No Fossils found of direct Echinoderms due to the lack of calcium carbonate in the Echinoderm’s exoskeleton Echinoderms are most closely related to the Phylum Chordata

Symmetry/Structural Support of an Echinoderm Symmetry- Echinoderms have Pentaradial symmetry –What's Pentaradial Symmetry? –Pentaradial Symmetry is a form of body symmetry where the body parts extend from the center along five spokes Ex. Star Fish Structural Support- Echinoderms have an endoskeleton composed of Ossicles –Ossicles are plates composed of calcium carbonate

Body Cavity of Echinoderms Body Cavity- Echinoderms have a Deuterostome body cavity –That means that in the embryos of echinoderms, the blastopore develops into the anus, and a second opening in the embryo becomes the mouth

Nutrition/Digestion Class Crinoidea –Sea lilies and Feather Stars-Feed by using their stick tube feet, which suck small organisms from the water –The organisms get filtered and get transported by cilia to the Crinoids' mouth which, unlike most echinoderms, faces up Class Ophiuroidea –Basket Stars and Brittle Stars-Use their long arms to rake food in, such as small organisms from the bottom of the ocean or from Coral reefs –Also, trap food particles with their tube feet or with mucous strands Class Echinoidea –Sea Urchins-Use their five teeth surrounding their mouth to scrape algae from surfaces –Sand Dollars- use their tube feet to capture food that lands on their body or swims over them

Nutrition/Digestion Cont… Class Holothuroidea –Sea Cucumbers – extend their tentacles, made up of miniature tube feet, out of their mouths and sweeps up food around itself –Then it brings its tentacles inside its mouth and cleans the food off of them

Nutrition/Digestion Cont… Class Asteroidea –Sea Stars are carnivorous and feed on mollusks, worms, clams, and slow moving objects –Sea Stars, once they capture their prey extract their cardiac stomach which sucks the food into itself –When finished the Cardiac Stomach goes back into the mouth and transfers the food to the Pyloric Stomach –The Pyloric Stomach is connected to digestive glands in each arm which digest the food completely and absorb the nutrients

Transportation/Circulation Echinoderms use the Water-Vascular System for Transportation The Water-Vascular System is a network of canals filled with water that connect to the tube feet of echinoderms and through water pressure the tube feet extend and contract causing the organism to move –Water enters the system through small pores in the madreporite –Then it heads to the stone canal, a tube that connects the madreporite to the ring canal, which goes around the mouth –Then the Radial canal extends from the ring canal to the end of each arm sending water to the tubes Confused? Here’s a Movie to show you the movement of the tube feetMovie Circulation- All Echinoderms lack a circulatory system however fluid from the coelom distributes nutrients and oxygen to the organism

Gas Exchange/Respiration Echinoderms don’t posses a system of Respiration except the fluid from the coelem that gives the organism oxygen Gas exchange takes place by diffusion through the skin gills, hollow tubes that protect from the coelom lining to the exterior Some echinoderms use their tube feet to exchange oxygen and carbon dioxide with the water

Water Balance/Excretion Echinoderms lack any main excretory systems, but do excrete their wastes through the thin walls of the tube feet Echinoderms use their tube feet to extract water and use their madreporite to take water in, which are part of the Water- Vascular System

Reproduction/Development Most species of echinoderms are separate sexes Each arm that is attached to the central region contains a pair of ovaries or testes which produce eggs or sperm Each is released from a different echinoderm and fertilization occurs externally Each fertilized egg develops into a bipinnaria, a bilaterally symmetrical free-swimming larva After a certain amount of time, usually two months, the larva settles to the bottom of the ocean or sea and begins metamorphosis During Metamorphosis the larva changes from a bilaterally symmetrical organism to a pentaradially symmetrical adult

Unique Characteristics and Facts Echinoderms are able to regenerate any one of their five appendages so long as it is attached to the central region Regeneration may take up to a year This can be used as a great defense mechanism Echinoderms have always been great souvenirs, so long as they have been properly dried Echinoderms are beloved characters of movies and television, most notably Patrick Star From SpongeBob SquarePants