In details

Protocordates



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.

Urocordates (Urochordata)

- 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).

Cephalocordates (Cephalochordata)

- 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

Domain: Eukaryota

Animal Kingdom

Sub-training: Eumetazoa

Superfile: Deuterostomy

Philo: Chordata

Biological Curiosities:

- 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.