Questions and Answers
What is ecology in relation to crinoids?
Approximately 600 species, deep sea.
What is the only echinoderm that lives with its oral side up?
Not provided.
What is the maximum amount of arms a crinoid can have?
Up to 700.
What does the fossil record indicate about crinoids?
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What feeding method do crinoids use?
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What are sessile crinoids commonly referred to as?
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What are motile crinoids commonly known as?
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What is a calyx in relation to crinoids?
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What are pinnules?
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What type of larva do crinoids produce?
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Study Notes
Crinoidea Overview
- Approximately 600 species exist, primarily found in deep-sea environments.
- Unique among echinoderms, they typically maintain an oral-side up orientation.
Physical Characteristics
- Crinoids can have a maximum of up to 700 arms.
- The calyx is a cube-shaped central disc that forms a significant part of their anatomy.
- Pinnules, which are branched off arms, contain tube feet and aid in feeding.
Fossil Record and Evolution
- Crinoids represent the oldest of the extant echinoderm classes with a rich presence in the fossil record.
Feeding and Lifestyle
- They primarily utilize suspension feeding, filtering particles from the water.
- Two main forms exist:
- Sessile crinoids (sea lilies) are stalked and anchored to substrates.
- Motile crinoids (feather stars) are non-stalked and can move freely, classified as comatulid crinoids.
Development
- The larval stage is represented by the Echinopluteus, which is a critical phase in their life cycle.
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Description
Explore the fascinating world of Crinoidea, characterized by their distinct physical traits, feeding strategies, and evolutionary history. This quiz delves into both sessile and motile forms, highlighting their adaptation to deep-sea environments. Test your knowledge about their anatomy, lifestyle, and development stages.
