Class ASTEROIDEA: sea stars [fig. 25.5-25.7]
- central disc merges gradually with arms
- carnivorous
- sea
star dissection from the University of Minneota
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Class OPHIUROIDEA: brittle stars [Fig. 25.8-25.9]
- central disc sharply set off from arms
- feed on suspended microorganisms, detritus
- S. Hottenrott's The Ophiuroidea
page has a wealth of information including links to ophiuroids as all-seeing
eyes research reporeted in Nature
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Class ECHINOIDEA: sand dollars and sea urchins [Fig. 25.10-25.11]
- compact body, spherical or flattened
- no arms; spines
- mainly herbivores
- Aristotle's lantern
- pedicelleria.
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Class HOLOTHUROIDEA: sea cucumbers [Fig. 25.12-25.13]
- bilaterally symmetric--slug-like
- leathery skin
- suspension or detritus feeders.
- respiratory trees
- more information and pictures from the Tree
of Life
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Class
CRINOIDEA: sea lilies [Fig. 25.1, 24.14, 25.15]
- usually stalkedcup
- branched arms for filter feeding
- dorsal mouth
- more information and pictures from the Tree
of Life
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