Archive | Phylum Chordata

Appearance of Chordate Characters in Protochordates

In this article we will discuss about the gradual appearance of chordate characters in protochordates . The chordates exhibit different gradations of structural organisation from simple to com­plex. The protochordates including the three subphyla—Hemichordata, Urochordata and Cephalochordata—are the primitive members of the Phylum Chordata. All of them lack verte­bral column and skull. They form an intermedi­ate group between the non-chordates [...]

By |2016-07-22T08:09:52+00:00July 22, 2016|Phylum Chordata|Comments Off on Appearance of Chordate Characters in Protochordates
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Classification of Subphylum Cephalochordata

In this article we will discuss about the classification of subphylum cephalochordata. Historical Resume of Subphylum Cephalochordata: The first individual of this group was des­cribed by Pallas in 1778. He regarded the speci­men as a slug and named it Umax lanceolatus. Yarrell (1836) studied the animal in detail and gave the name Amphioxus lanceolatus. Costa (1834) suggested the name of [...]

By |2016-07-22T08:09:52+00:00July 22, 2016|Phylum Chordata|Comments Off on Classification of Subphylum Cephalochordata
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Balanoglossus, Ascidia and Branchiostoma | Phylum Chordata

Let us learn about the comparison between balanoglossus, ascidia and branchiostoma. Comparison # Balanoglossus: 1. The pharynx is an elon­gated structure which is internally divided into 2 incomplete upper and lower halves by a longi­tudinal parabranchial ridge or Para pharyngeal ridge. The upper one is called the respiratory por­tion and the lower part is the digestive chamber. 2. The pharynx [...]

By |2016-07-22T08:09:52+00:00July 22, 2016|Phylum Chordata|Comments Off on Balanoglossus, Ascidia and Branchiostoma | Phylum Chordata
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