Echinoderm and chordate comparative organization
Echinoderms characteristically have a calcareous internal skeleton and a water vascular system associated with tube feet; typical adults are pentaradial even though their ancestry lies within bilaterian animals.
Key knowledge
Echinoderms characteristically have a calcareous internal skeleton and a water vascular system associated with tube feet; typical adults are pentaradial even though their ancestry lies within bilaterian animals. Chordates display a notochord, dorsal hollow nerve cord, pharyngeal apparatus, post-anal tail and endostyle or thyroid-related structure at some developmental stage. Adult retention and modification differ among tunicates, lancelets and vertebrates.
Conditions and scope
- An echinoderm ossicle is calcareous material, not automatically vertebrate bone.
- Chordate characters need not all persist in an adult; notochord remnants and retained structures vary among vertebrates.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Mary Ann Clark, Matthew Douglas and Jung Choi — OpenStax, Rice University2 sources
- Biology 2e, 28.7 Echinoderm Skeleton and Water Vascular SystemMary Ann Clark, Matthew Douglas and Jung Choi — OpenStax, Rice UniversityTextbook chapter
- Biology 2e, 29.1 Chordate Characters and Developmental VariationMary Ann Clark, Matthew Douglas and Jung Choi — OpenStax, Rice UniversityTextbook chapter
Evidence and review
Read echinoderm ossicle/tube-foot and chordate five-character, tunicate metamorphosis and notochord-remnant passages; excluded source's all-vertebrates-no-adult-notochord contradiction and universal blastopore/cloning assertions.
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Entry details
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