Phylum Chordata and Classification

They have a body that is bilaterally symmetrical, and they are classified into three separate sub-phyla.It is a continuation of the body’s expansion to the anus. Chordates have a tail that is made up of skeletal muscles that aid in locomotion in fish-like animals. It is not present in the majority of adult Chordates.

Features of the Phylum Chordata

There are many features of Phylum Chordata, some of which are given here.

Notochord

Between the nerve cord and the digestive tract, it is a cartilaginous rod that runs longitudinally across the body. Following the embryonic stage in all vertebrates, it serves as a support for the nerve cord and is replaced by the vertebral column after that stage.

The Dorsal Nerve Cord is a type of nerve cord that runs along the back of the neck.

It is a bundle of nerves that runs along the “back” of the body and divides into two parts: the brain and spinal cord. It is hollow and is located dorsal to the notochord on the thoracic spine.

Slits in the Pharynx

As the name implies, these are the apertures that allow water to pass through the mouth without entering the digestive system; in other words, they connect the mouth and the throat. The lateral sides of the pharynx on the lateral sides of all Chordates have these apertures at some point in their lives.

Other traits of Chordates

Body with a bilaterally symmetrical shape, triploblastic structure, coelomic structure, and segmented body.

The body design is complicated and distinct from the rest of the vehicle.

The organ systems of the body are the highest level of organisation in the organism.

Classification of the Phylum

The phylum Chordata is subdivided into three subphyla, which are as follows:

Vertebrates include the Urochordata (tunicates) and Cephalochordata (lancelets) (vertebrates).

Chordata are classified into four classes.

Chordata is divided into three subphyla, according to its classification.

Protochordates are marine organisms that belong to the subphylum Urochordata and Cephalochordata, which are both subphyla of the phylum Urochordata. They are invertebrates, however they have characteristics that are similar to chordates.

Urochordata

The adults have become firmly attached to the substratum.

It is sometimes referred to as Tunicate because the adult’s body is contained within a tunic made of a cellulose-like substance known as tunicin, which is a cellulose-like substance.

The notochord is only visible during the larval stage and vanishes during the adult stage.

In adults, the dorsal ganglion takes the place of the nerve cord that was present in larvae.

The larva has the ability to move and goes through a metamorphosis.

Ascidia, Salpa, and Doliolum are examples of such plants.

Cephalochordata

There is an atrium present.

Adult and larval stages of the motile species.

The tail is present at all stages of life.

They go through a process of metamorphosis.

The notochord can be found in all stages of life.

A large number of well-developed pharyngeal gill slits can be found.

Lancelets, for example, have the notochord and nerve cord throughout their whole life span. They, unlike Branchiostoma, do not have a brain or a bony vertebral column, as does the latter.

Vertebrata

Vertebrates have several distinguishing characteristics, which are as follows:

There is a cranium around the brain of these advanced chordates, indicating that they are higher-level chordates.

When a child grows up, the notochord is replaced by a vertebral column. Hence, “all vertebrates are chordates,” but not “all chordates are vertebrates,” as the adage goes.

There is a significant amount of cephalisation observed.

The epidermis is composed of several layers.

They are made up of three different types of muscles: striped, unstriped, and cardiac muscles.

They have a coelom that is nicely developed.

The alimentary canal has been completely completed.

The heart has three or four chambers, depending on the size.

Their respiratory and excretory systems are both well-developed in this species.

Endocrine glands can be found in all mammals.

Hagfish, on the other hand, is an exception, as they are unisexual and reprodce sexually.

Conclusion 

Therefore it can be concluded, Animals belonging to phylum Chordata are fundamentally characterised by the presence of a notochord, a dorsal hollow nerve cord and paired pharyngeal [relating to the pharynx] gill slits.

They are bilaterally symmetrical, triploblastic, coelomate with organ-system level of organisation.