phylum echinodermata
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A starfish, a member of the phylum Echinodermata, crawls slowly across the ocean floor.
Definition
Proper noun A major taxonomic rank in biological classification, specifically a phylum within the kingdom Animalia. It comprises exclusively marine invertebrates characterized by a unique combination of features: a calcareous endoskeleton, a water vascular system with tube feet, and (in adults) pentaradial symmetry—a body plan organized in five parts around a central axis.
Usage and Examples
Scientific Classification:
- The study focused on the evolutionary history of phylum Echinodermata.
- Sea stars, brittle stars, and crinoids are all classes within phylum Echinodermata.
Descriptive Context:
- The unique water vascular system is a defining characteristic of phylum Echinodermata.
- Fossil records show that phylum Echinodermata has a long and diverse history.
Advanced Usage and Notes
- The term is used almost exclusively in formal scientific, biological, and zoological contexts. In general communication, the common names for its member classes (e.g., starfish, sea urchins) are used instead.
- While adults exhibit radial symmetry, the larval stages of organisms in this phylum are bilaterally symmetrical, a key point in understanding their evolution.
Variants and Related Terms
- Echinoderm (noun): Any member of the phylum Echinodermata.
- The tide pool was full of various echinoderms.
- Echinodermal (adjective): Of or relating to the phylum Echinodermata.
- The researcher studied echinodermal anatomy.
Synonyms and Related Concepts
- Echinoderms: This is the direct common-name equivalent for the members of the phylum.
- Marine invertebrates: A broader category that includes phylum Echinodermata along with many other phyla like Mollusca and Arthropoda.
Key Member Classes (Illustrative, not synonyms)
- Asteroidea: The class containing sea stars (starfish).
- Echinoidea: The class containing sea urchins and sand dollars.
- Holothuroidea: The class containing sea cucumbers.
- Ophiuroidea: The class containing brittle stars and basket stars.
- Crinoidea: The class containing sea lilies and feather stars.
A starfish, a member of the phylum Echinodermata, crawls slowly across the ocean floor.
Noun
- radially symmetrical marine invertebrates including e.g. starfish and sea urchins and sea cucumbers