ascidian tadpole
Học thuậtThân thiện
Definition
Noun: A free-swimming larval stage of ascidians (sea squirts), characterized by a tail that resembles that of a tadpole and contains a notochord, a defining structure of chordates.
Usage
The term is used in zoology and marine biology to describe a specific, transient developmental form. It highlights a key evolutionary link, as the larva possesses a primitive backbone (notochord) that is lost in the sedentary adult form. - The ascidian tadpole swims briefly before settling and metamorphosing into an adult sea squirt. - Studying the ascidian tadpole provides insights into chordate origins.
Advanced Usage
- The ascidian tadpole is a classic example of a larval form that exhibits characteristics (like the notochord) not present in the adult organism, a concept known as "retrogressive metamorphosis."
Variants and Related Words
- Ascidian (n): The adult form, a sessile marine invertebrate of the class Ascidiacea.
- Tadpole (n): The aquatic larval stage of frogs and toads, used here by analogy due to the similar tail shape.
- Larva (n): The immature, free-living form of an animal that undergoes metamorphosis.
Synonyms
- Ascidian larva
- Urochordate tadpole larva
Related Phrases/Idioms
Not commonly used in idioms. It is a precise scientific term.
Noun
- free-swimming larva of ascidians; they have a tail like a tadpole that contains the notochord