EchinodermataEchinodermata

Olivia Johnson, Andrei Olivia Johnson, Andrei Anashkin, Heather SchlesierAnashkin, Heather Schlesier

http://www.dailywhatever.net/wp-content/uploads/2009/02/sea-cucumber-ga.jpg

• Echinoderms are slow-moving animals that Echinoderms are slow-moving animals that only live in salt wateronly live in salt water

• A unique feature is the water vascular A unique feature is the water vascular systemsystem

• The phylum The phylum EchinodermataEchinodermata contains 6 contains 6 major classes: Asteroidea (sea stars), major classes: Asteroidea (sea stars), Ophiuroidea (brittle stars), Echinoidea (sea Ophiuroidea (brittle stars), Echinoidea (sea urchins and sand dollars), Crinoidea (sea urchins and sand dollars), Crinoidea (sea lilies and feather stars), Holothuroidea lilies and feather stars), Holothuroidea (sea cucumbers), and Concentricycloidea (sea cucumbers), and Concentricycloidea (sea daises)(sea daises)

PhylumPhylum

Sample AnimalsSample AnimalsA Sea Star A Brittle Star

A Feather Star

http://www.coral.org/files/images/7628-SeaStar.jpg

http://www.cartage.org.lb/en/themes/Sciences/Zoology/Animalclassification/Polygenetic/phylogenetictree/Echinodermata/ophiuroidea.jpg

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A Sea Urchin

A Sea Cucumber

A Sea Daisy

4 5

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http://www.reefseekers.com/PIXPAGES/Yap-Palau%20%2704/Grazing_sea_cucumber.jpg

Body CavityBody Cavity

-are coelomates (posses a true -are coelomates (posses a true coelom)coelom)

-coelom (body cavity): a fluid-filled -coelom (body cavity): a fluid-filled space that separates the digestive space that separates the digestive tract from the outer body walltract from the outer body wall

-coelom is lined with mesoderm-coelom is lined with mesoderm

Body SymmetryBody Symmetry• Adults have radial symmetry but it is Adults have radial symmetry but it is

a secondary adaptation (many equal a secondary adaptation (many equal parts radiate outward like the spokes parts radiate outward like the spokes of a wheel)of a wheel)

• Echinoderm larvae have bilateral Echinoderm larvae have bilateral symmetry (can be divided into two symmetry (can be divided into two equal halves) equal halves)

• Echinoderms have a decentralized Echinoderms have a decentralized nervous system.nervous system.

• There is nervous tissue throughout the There is nervous tissue throughout the echinoderm connected by central echinoderm connected by central nerve ring around its gut, but they nerve ring around its gut, but they have no real brain.have no real brain.

• Some echinoderms instead have Some echinoderms instead have ganglia, which are large clusters of ganglia, which are large clusters of nerve cells .nerve cells .

Nervous SystemNervous System

Water Vascular SystemWater Vascular System

• Unique to echinoderms it is a Unique to echinoderms it is a network of hydraulic canals network of hydraulic canals branching into extensions called tub branching into extensions called tub feet that function in locomotion, feet that function in locomotion, feeding, and gas exchangefeeding, and gas exchange

Circulatory SystemCirculatory System

Digestive SystemDigestive System

Excretory SystemExcretory System

• Excretion can be preformed through Excretion can be preformed through diffusiondiffusion

• Contains an anus on the top of the Contains an anus on the top of the central diskcentral disk

• Made possible by the water vascular system Made possible by the water vascular system and tube feetand tube feet

• Sea StarsSea Stars: undersurfaces of the arms have : undersurfaces of the arms have tube feet, adheres firmly to rocks or creeps tube feet, adheres firmly to rocks or creeps along slowly as the tube feet extend, grip, along slowly as the tube feet extend, grip, contract, release, extend and grip again.contract, release, extend and grip again.

– Made possible by a complex set of hydraulic Made possible by a complex set of hydraulic and muscular actions creating or releasing and muscular actions creating or releasing suction.suction.

• Brittle Stars: Brittle Stars: serpentine lashing of their armsserpentine lashing of their arms– Tube feet lack suckers so cannot gripTube feet lack suckers so cannot grip

Locomotion/ MusculatureLocomotion/ Musculature

• Sea Urchins and Sand Dollars: Sea Urchins and Sand Dollars: don’t have don’t have arms, but do have 5 rows of tube feet that arms, but do have 5 rows of tube feet that function in slow movementfunction in slow movement– Also have muscles that pivot their long spines that aids Also have muscles that pivot their long spines that aids

in movementin movement• Sea Lilies and Feather Stars: Sea Lilies and Feather Stars: Sea lilies live Sea lilies live

attached to the substrate by a stalk; feather stars attached to the substrate by a stalk; feather stars crawl about by using their long flexible armscrawl about by using their long flexible arms

• Sea CucumbersSea Cucumbers: have 5 rows of tube feet, some : have 5 rows of tube feet, some of the tube feet around the mouth are developed of the tube feet around the mouth are developed as feeding tentaclesas feeding tentacles

• Sea Daisies:Sea Daisies: they have armless bodies, not they have armless bodies, not much is known about themmuch is known about them

Skeletal TypeSkeletal Type

• A thin skin covers an endoskeleton of A thin skin covers an endoskeleton of hard calcareous plateshard calcareous plates

• Most echinoderms are prickly from Most echinoderms are prickly from skeletal bumps and spinesskeletal bumps and spines

• Regeneration allows some echinoderms to grow Regeneration allows some echinoderms to grow back lost arms or even full bodiesback lost arms or even full bodies

• They have light and touch detecting cells but no They have light and touch detecting cells but no sense organssense organs– Starfish are an exception, they have eyespots Starfish are an exception, they have eyespots

on the tip of each ray for light detectionon the tip of each ray for light detection

• They do not have heads or a brain, instead they They do not have heads or a brain, instead they have a simple nervous system with a nerve net/ have a simple nervous system with a nerve net/ ringring

Sensory Structures/FeaturesSensory Structures/Features

•Sexual or asexual (regeneration)Sexual or asexual (regeneration)

•Sexual reproduction usually involves Sexual reproduction usually involves separate male and female individuals that separate male and female individuals that release their gametes into the waterrelease their gametes into the water

•Sea stars and some other echinoderms Sea stars and some other echinoderms have the ability to regeneratehave the ability to regenerate

•Sea stars can regrow lost arms, and one Sea stars can regrow lost arms, and one specific genus can regrow an entire body specific genus can regrow an entire body from a single armfrom a single arm

ReproductionReproduction

Gas ExchangeGas Exchange

• Do not have a circulatory systemDo not have a circulatory system

• Exchange gas through diffusionExchange gas through diffusion

• Diffusion is possible through the Diffusion is possible through the water vascular systemwater vascular system

• Structures: tube feetStructures: tube feet

Other Unique Stuff Other Unique Stuff

• When feeding sea stars turn their When feeding sea stars turn their stomachs inside out and then stomachs inside out and then secretes juices to help it digest its secretes juices to help it digest its preyprey

• Current sea lilies are very similar to Current sea lilies are very similar to fossils of those that are 500 million fossils of those that are 500 million years old: their evolution has been years old: their evolution has been very conservativevery conservative

Which of the following do Which of the following do echnodermata contain?echnodermata contain?

• Circulatory systemCirculatory system

• ExoskeletonExoskeleton

• EndoskeletonEndoskeleton

• Nervous systemNervous system

What kind of symmetry do What kind of symmetry do grown echinodermata have?grown echinodermata have?

• BilateralBilateral

• SymmetricalSymmetrical

• Secondary radial Secondary radial