Subphylum Urochordata is divided into three classes.   CLASS 1.  ASCIDIACEA CLASS 2. THALIACEA CLASS 3. LARVACEA (APPENDICULARIA)   CLASS 1. ASCIDIACEA:   These are sedentary tunicates. The body is…
The tunicates were first regarded as sponges. Lamark in 1816 placed Tunicata in between the Radiata and Vermes in his system of classification. Later, they were included in Mollusca. In…
The development of organ system is called as Organogeny. In Amphioxus the gastrula elongates in the future anteroposterior direction and the blastopore comes nearer to the posterior end of the…
FATEMAP OF FERTILISED EGG OF AMPHIOXUS: Conklin in 1932 studied the fate map of Amphioxus. In 1962 Tunguntung described the egg of amphioxus 4 regions are clearly seen.   Clear…
Amphioxus is a Cephalochordate animal. Its Life history in the early stages shows resemblance with ascidians. HATSCHE’K WILSON. CONKLIN’ worked on the part of embryogenesis of Amphioxus. ‘CONKLINS’ work in…
In amphioxus a big space is present, called Atrium it is lined by ectoderm. It encloses pharynx, and part of intestine. It opens out through atriopore at 36 myotome in…
In the Urochordate and Cephalochordate animals the ventral side of the pharyhx wilI contains endostyle. It is a glandular ciliated groove present on the floor of the pharynx. This contains…
In chordate animals notochord, dorsal tubular nerve cord and pharyngeal slits are present.   In Amphioxus notochord is a cylindrical rod extending the whole length of the body from anterior
Exoskeleton is absent in Branchiostama. Endoskeleton include the notochord, gelatinous rods and plates, fin-ray boxes etc.   1. Notochord in Amphioxus: The notochord of Amphioxus is extending the whole length…
Amphioxus belongs to Cephalochordate. In 1778 Amphioxus was first discovered and described by Palias. He called it a Molluscan animal. In 1834, it was described as a chordate animal by…

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