Polycarpa aurata: example of protocordate (urocordate)
What they are (definition)
Protocordates are chordate marine animals that do not have a skull and spine.
Summary of General Features:
- Presence of notochord (dorsal cord);
- Nervous system with dorsal position (dorsal nerve tube);
- Presence of gill slits (small holes present in the pharynx and responsible for breathing or filtering food);
- Absence of cranial box;
- They have no brain;
- Absence of spine (as occurs in vertebrate animals).
* Featuring all the characteristics of chordates.
Subphiles, characteristics and examples:
The protocordates can be divided into two subphiles (groups) according to some specific characteristics.
- Main features: presence of notochord in the larval phase (in adulthood loses the notochord) restricted to caudal area. Another feature is the existence of a sacculiform body (small sac shape).
- Example: Sea Syringes (ascidian).
- Main features: They have body with flat shape. Existence of notochord from head to tail until adulthood.
- Example: Amphioxo (also known as animal filter).
Scientific Classification:Domain: EukaryotaReum: AnimalSubreine: EumetazoaSurface: DeuterostomyFilo: Chordata
- There are few species of these animals in the wild.
- Amphioxes (cephalocordate) have embryonic development very similar to that of humans.
Sea syringes: example of a protocordated animal.