Define the term :-
• Non Chordate
• Chordate
Answers
Answer:
Non-chordates are animals without a notochord – the rod-like elastic structure that supports the body. This phylum consists of a small group of worm-like, marine species with an organ-system level of organization.
Members of phylum Porifera, Coelenterata, Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata and Hemichordata fall under Non-chordates.
The general characteristic features of Non-Chordates are:
They are cylindrical, triploblastic, coelomate, or pseudocoelomate animals.
Respiration in these animals takes place through gills, trachea or body surface.
Most of the times, sexes cannot be distinguished among the members.
Modes of reproduction involve sexual and asexual
Fertilization is external, though internal fertilization also occurs in some species.
The body of non-chordates generally includes an open type of circulatory system
Chordates
Chordates are animals characterized by the presence of notochord at some stage during their development. Members possess a hollow nerve cord and pharyngeal gill slits. The other general characteristic features of Chordates are as follows:
They are bilaterally symmetrical, triploblastic, and coelomate with the organ-system level of organization.
They hold a post-anal tail
The body includes a closed circulatory system.
In some members of Phylum Chordata, the notochord is present only in the larval tail, and in some, it is present throughout their life from head to tail region.
Chordates have many sub-divisions and Protochordates are one of the earliest to evolve.
Phylum Chordata is divided into three subphyla: Urochordata, Cephalochordata, and Vertebrata.
Subphylum – Urochordata
It is also referred to as Tunicata which are marine animals. The body of these animals is surrounded by a leathery covering (similar to a tunic, hence the name). Larvae are free-swimming, the notochord is present only in the tail of larvae and after settling on the seabed, they get transformed into sessile adults. They are generally hermaphrodites.
Examples include – Ascidians, Doliolum, Oikopleura, etc.
Subphylum – Cephalochordata
It mainly consists of small, fish-like marine animals in which the notochord is extended along the entire body. The animals also have pharynx, which is large with numerous gill- slits. Members of this subphylum have separate sexes.
Example include – Amphioxus or lancelet.
Subphylum – Vertebrata
In this subphylum, the notochord is present in the embryonic stages and is replaced by a vertebral column in the adult. They have 2, 3 or 4 chambered heart, paired appendages for locomotion and kidneys for excretion or osmoregulation.
Explanation: hope it helps you sis!
