urochord
Học thuậtThân thiện
Definition
- Noun (Zoology):
- A defining anatomical structure: A flexible, rod-like skeletal structure found in the tail region of larval tunicates (sea squirts). It is a primitive form of a notochord, which is a defining feature of the phylum Chordata.
- A common name for an animal: A common name for any marine invertebrate animal belonging to the subphylum Urochordata (Tunicata), characterized by having a sac-like, unsegmented body and, typically, a larval stage with a prominent urochord.
Usage Examples
Noun (Anatomical Structure):
- The presence of a urochord in the tadpole-like larva is evidence of the tunicate's chordate ancestry.
- During metamorphosis into the adult form, the larval urochord is resorbed.
Noun (Animal):
- The sea squirt is a familiar type of urochord found attached to rocks and piers.
- Scientists study urochords to understand the evolution of vertebrates.
Advanced Usage
- In taxonomic classification, "Urochordata" is synonymous with "Tunicata," a subphylum within the Chordata.
- Urochords, despite their simple adult form, are classified as chordates due to their larval characteristics.
Variants and Related Words
- Urochordate (n): A member of the subphylum Urochordata; a tunicate.
- The collection included several species of urochordates.
- Tunicate (n): Another name for an animal in the subphylum Urochordata, referring to its outer covering or "tunic."
- The tunicate filter-feeds water through its siphon.
Synonyms
- For the animal: tunicate, sea squirt.
- For the structure: larval notochord, caudal notochord.
Related Terms (Contextual)
- Notochord: The defining rod-like structure of all chordates, of which the urochord is a specific, transient type.
- Chordate: An animal belonging to the phylum Chordata, characterized by having a notochord at some stage of its life cycle.
Noun
- a notochord of a larval tunicate typically confined to the caudal region
- primitive marine animal having a saclike unsegmented body and a urochord that is conspicuous in the larva