general characteristics spiny skinned lack segmentation...
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General Characteristics Spiny skinned
Lack segmentation
Radial symmetry
Water vascular system
• All marine
• Test made of calcium plates with
protruding spines
• Bilateral, free-swimming larva to sessile
adult
• Adults have pentaradial
(5 part) symmetry
• Separate sexes
Capable of extensive regeneration
• Ventral surface called the oral surface &
where mouth is located
• Dorsal surface known as aboral surface
& where anus is located
• Have a nervous system, but no head or
brain in adults
• No circulatory, respiratory, or excretory
systems
• Have a network of water-filled canals
called the water vascular system to
help move & feed
• Tube feet on the underside of arms
help in moving & feeding
• One-way digestive system consists
of mouth with oral spines, gut, &
anus
Class Asteroidea – sea stars
C. Ophiuroidea – brittle stars
C. Echinoidea – sea urchins/sand dollar
C. Crinoidea – sea lily/feather star
C. Holothuroidea – sea cucumber
Echinoderm Classification
C. Asteroidea – starfish or sea stars
• Usually along shorelines
• Come in a variety of colors
• Prey on bivalve mollusks such as
clams & oysters
• Have 5 arms that can be regenerated
• Arms project from the central disk
•Have pedicellariae or tiny, forcep-like
structures surrounding their spines to help
clean the body surface
• Reproduce sexually & asexually
• Have external fertilization
• Females produce up to 200,000,000
eggs per season
Examples:
Atlantic Sea star: east coast
Bat Star : west coast
Sun Star: 15 to 20 arms, Pacific coast
Crown of Thorns: up to 80 cm, 4-5cm
spines, Great Barrier Reef
Class Crinoidea - sea lilies &
feather stars
FEATHER STAR
SEA LILY
• Have a long stalk with branching arms
that attach them to rocks & the
ocean bottom
• Can detach & move around
• May have 5 to 200 arms with sticky
tube feet to help capture food (filter
feeders) & take in oxygen
• Common in areas with strong currents
& usually nocturnal feeders
Class Ophiuroidea – brittle stars
• Largest class of echinoderms
• Live on the ocean bottom beneath
stones, in crevices, or in holes
• Have long, narrow arms
• Arms readily break off & regenerate
• Move faster than starfish
• Feed by raking in food with arms or
trapping it with its tube feet
Class Echinoidea – sea urchins &
sand dollars
• Internal organs enclosed by
endoskeleton or test made of fused
skeletal plates
• Body shaped like a sphere (sea urchin)
or a flattened disk (sand dollar)
• Lack arms
• Bodies covered with movable spines
• Have a jaw-like, crushing structure
called Aristotle's lantern to grind food
Sea Urchins:
* Spherical shape
* Live on ocean bottom
* Scrape algae to feed
* Long, barbed spines make venom
for protection
Sand Dollars:
* Flattened body
* Live in sand along coastlines
* Shallow burrowers
* Have short spines
Class Holothuroideasea cucumbers
• Lack arms
• Shaped like a pickle or cucumber
• Live on ocean bottoms (hide) in caves
during the day
• Have a soft body with a tough, leathery
outer skin
• Five rows of tube feet run lengthwise
on the aboral surface of the body
• Have a fringe of tentacles (modified
tube feet) surrounding the mouth to
sweep in food &
•water
• Tentacles have sticky
ends to collect
plankton
•Show bilateral symmetry
•Can eject parts of their internal organs
(evisceration) to scare predators;
regenerate these structures in days
The Giant California Sea Cucumber (up to 40cm)