Three important subphyla of Protochordates that are.
ANNELID THEORY-ORIGIN OF CHORDATES: This theory suggests that the chordates have evolved from an annelid stock. The annelids show bilateral symmetry, mesmerism, head, lateral Coelome complete digestive tract, closed circulatory system, hemoglobin, etc., like chordates. The resemblance is enhanced if, an annelid is turned upside down.
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Classification of Protochordata and Cyclostomata; evolution, affinities and phylogeny of protochordates. Structure, function and life histories of Pyrosoma, Doliolum, Salpa and Oikopleura. Evolution and affinities of Cyclostomata. Unit 2 Classification, origin, evolution and deep sea adaptations in fishes, Parental care.
Start studying Chapter 2 Phylogenetic Relationships of Chordates and Craniates. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
Origin of chordates Chordates evolved sometime during Cambrian period, 500 million years ago during Cambrian explosion, almost at the same time when invertebrates were beginning to evolve. They may have evolved from some freshwater forms as Chamberlain (1900) pointed out that all modern chordates possess glomerular kidneys that are designed to remove excess water from body.
Looking for Protochordate? Find out information about Protochordate. any animal of the phylum Chordata, including the vertebrates and protochordates, characterized by a notochord, dorsal tubular nerve cord, and pharyngeal.
Protochordates are an informal category of animals (i.e.: not a proper taxonomic group), named mainly for convenience to describe invertebrate animals that are closely related to vertebrates. This group is composed of the Phylum Hemichordata and the Subphyla Urochordata and Cephalochordata.