What is the Difference Between Urochordata and Cephalochordata?

Urochordata and Cephalochordata are two subphyla of the phylum Chordata, which are characterized by the presence of a notochord, a dorsal nerve cord, and pharyngeal slits. They are marine invertebrates that share some common features but also have distinct differences:

Urochordata:

1. Also known as tunicates.
2. Filter feed by pumping seawater through their bodies to catch planktonic particles.
3. Notochord is present only in the larval stage and is located in the back of the body.
4. Coelom is absent.
5. Have a heart and an open circulatory system.
6. Nephrocytes are responsible for excretion.
7. Sexual reproduction is through broadcast spawning.
8. Examples include Herdmania, Doliolum, and Oikopleura.

Cephalochordata:

1. Also known as lancelets.
2. Closer to echinoderms than vertebrates.
3. Notochord extends to the head region and is present throughout the adult lifespan.
4. Coelom is present.
5. Circulatory system is closed.
6. Protonephridia and solenocytes excrete waste.
7. Examples include Branchiostoma and Amphioxus.

In summary, Urochordata and Cephalochordata are both chordate subphyla that share some common features, such as the presence of a notochord, dorsal nerve cord, and pharyngeal slits. However, they differ in the presence and location of the notochord, the presence of a coelom, the structure of the circulatory system, and the method of excretion.

Comparative Table: Urochordata vs Cephalochordata

Here is a table comparing the differences between Urochordata and Cephalochordata:

Urochordata is a chordate group that includes tunicates, and they are closer to vertebrates. They have a notochord only in the back of the body, lack a coelom, and have a heart with an open circulatory system. Their excretion is carried out by nephrocytes. During the larval stage, they swim freely, but adults are sessile. They reproduce asexually through budding and are hermaphrodites or bisexual. Examples include Herdmania, Doliolum, and Oikopleura.

Cephalochordata is a chordate group that includes lancelets, and they are closer to echinoderms. Their notochord extends all the way to the head region, they have a coelom, and their circulatory system is closed. Excretion is carried out by protonephridia and solenocytes. They are free-swimming fish-like creatures throughout their lives. They are not capable of asexual reproduction and are unisexual creatures. Examples include Branchiostoma and Amphioxus.