Phylum Echinoderms

InvertebratesInvertebrates

• EchinodermsEchinoderms• Characteristics of Phylum:Characteristics of Phylum:

– Name means "Spiny Skin" Name means "Spiny Skin" – EndoskeletonEndoskeleton– Water vascular system with tube feet important in feeding and Water vascular system with tube feet important in feeding and

locomotionlocomotion– Skin gills for respiration.Skin gills for respiration.– Radial symmetry in adults- larvae are bilaterally symmetricalRadial symmetry in adults- larvae are bilaterally symmetrical– Nervous system is decentralized- no brain- this allows any Nervous system is decentralized- no brain- this allows any

portion of the body to leadportion of the body to lead– Can regenerate lost body partsCan regenerate lost body parts– All 7000 species exclusively marineAll 7000 species exclusively marine

InvertebratesInvertebrates

• Types of Echinoderms:Types of Echinoderms:• Sea stars-Sea stars-

– Move with tube feetMove with tube feet– Have a central disc in center of body surrounded by Have a central disc in center of body surrounded by

five arms (or multiples of 5 arms – some species have five arms (or multiples of 5 arms – some species have 50 arms)50 arms)

– Internal organs extend through the entire body, Internal organs extend through the entire body, including the armsincluding the arms

– Calcium carbonate plates are loosely embedded in Calcium carbonate plates are loosely embedded in spiny skin making them slightly flexible spiny skin making them slightly flexible

– Carnivores that normally consume shellfish and coralCarnivores that normally consume shellfish and coral

InvertebratesInvertebrates

• Types of EchinodermsTypes of Echinoderms• Brittle starsBrittle stars

– Like sea stars, they have a central disc surrounded by Like sea stars, they have a central disc surrounded by armsarms

– Five arms seen in brittle stars are thin and covered in Five arms seen in brittle stars are thin and covered in numerous spinesnumerous spines

– Internal organs are restricted to the central discInternal organs are restricted to the central disc– The tube feet present in brittle stars are without The tube feet present in brittle stars are without

suckers and used for feeding on detritus and small suckers and used for feeding on detritus and small animalsanimals

InvertebratesInvertebrates

• Types of EchinodermsTypes of Echinoderms• Sea Urchins, Sea Biscuits, Sand DollarsSea Urchins, Sea Biscuits, Sand Dollars

– Elongated, movable spines much longer than those Elongated, movable spines much longer than those sea in other groupssea in other groups

– Rigid plates are fused into a solid structure called a Rigid plates are fused into a solid structure called a “test”“test”

– Move with tube feetMove with tube feet– Mouth on the bottom, anus on top of bodyMouth on the bottom, anus on top of body– Biting mouth for grazing– aristotles lantern is the Biting mouth for grazing– aristotles lantern is the

feeding structure of muscles and mouthpiecesfeeding structure of muscles and mouthpieces– Feed on detritus, encrusting organisms, algae or Feed on detritus, encrusting organisms, algae or

anything else they can scrape off surfacesanything else they can scrape off surfaces

InvertebratesInvertebrates

• Types of EchinodermsTypes of Echinoderms

• CrinoidsCrinoids– Represented by feather stars and sea liliesRepresented by feather stars and sea lilies– 600 species are typically found in deep water600 species are typically found in deep water– Sea lilies live attached while feather stars are Sea lilies live attached while feather stars are

mobilemobile– These organisms have 5 or more arms that These organisms have 5 or more arms that

branch out for suspension feeding branch out for suspension feeding – Some use a mucous net to aid in food captureSome use a mucous net to aid in food capture

InvertebratesInvertebrates• Types of EchinodermsTypes of Echinoderms• Sea cucumbersSea cucumbers

– Five rows of two feet are restricted to one side, where Five rows of two feet are restricted to one side, where the animal liesthe animal lies

– The plates found in the sea cucumbers are loosely The plates found in the sea cucumbers are loosely embedded in the thick skinembedded in the thick skin

– They are deposit feedersThey are deposit feeders– Sea cucumbers have a interesting predator escape Sea cucumbers have a interesting predator escape

plan called evisceration, where they expel the internal plan called evisceration, where they expel the internal organs; it is assumed this allows escape for the sea organs; it is assumed this allows escape for the sea cucumber.cucumber.

– Since all echinoderms have regenerative capabilities, Since all echinoderms have regenerative capabilities, these internal organs will grow back.these internal organs will grow back.