What is Branchiostoma (=Amphioxus): They are marine fish-like animals, due to the presence of all the three fundamental Chordate characters they are considered as Chordata and placed under Subphylum Chephalochordata. On external appearance, they look like lances so they are also popular as ‘lancelet’ or ‘lancet’. In Branchiostoma the notochord is present up to the … Read more
In Branchiostoma nervous system is very simple with a dorsal nerve cord, nerves, sense organs but there is no well-developed brain in Branchiostoma. Central Nervous System of Branchiostoma: Branchiostoma does not have a proper brain, the hollow dorsal nerve cord or neural tube represents the central nervous system in Branchiostoma. In Branchiostoma the notochord extends … Read more
In Branchiostoma primary excretion occur through nephridia, the nephridia in Branchiostoma is ectodermal in origin. In higher Chordate primary excretory organ is kidneys and it is mesodermal origin but in the case of Branchiostoma, it is ectodermal. Protonephridia: On the dorsolateral wall of the pharyngeal region around 100 protonephridia are present on either side of … Read more
Respiratory System of Branchiostoma: In Branchiostoma respiration occur through the general surface area of metapleural folds, atrial wall, pharyngeal wall. The blood vessels present on the body wall and the oxygen present in the water current come close contact and gaseous exchange take place. The gill slits and gill bars have no special arrangements of … Read more
The digestive system of Branchiostoma is a complete and long tube with digestive glands associated with the alimentary canal. Alimentary Canal: As we know that the digestive system in Branchiostoma is complete and it starts from the mouth and ends in the anus. The diameter of the lumen of the digestive tract is not equal … Read more
Coelom in Branchiostoma: In Branchiostoma the body cavity is true coelom and the coelom is lined by mesodermal tissue. In Branchiostoma the coelom originate during embryonic development from the archenteron, so in Branchiostoma coelom is enterocoelous type. The body cavity or the cavity inside the coelom is filled with lymph like fluid. The coelom surround … Read more
The body wall in Branchiostoma have three layers, from outside to inside the three layers are the outermost skin layer, middle muscular layer and inner parietal peritoneum. Skin: It is the outermost thin delicate layer, this layer is made of a single layer of columnar epithelium cells. The columnar epithelium cells present on the basement … Read more
Shape of Branchiostoma: Branchiostoma has a lance-like shape, both anterior and posterior end of the body tapering and pointed. But the posterior end is more tapering than the anterior part, the lance-like shape makes them famous in the common name Lancelets. The body is laterally compressed and this lance-like streamlined body makes them suitable for … Read more
What is Branchiostoma(=Amphioxus): It is a marine almost fish-like small animal under Subphylum Chephalochordata. They are considered simplified Chordata because they have all the three fundamental Chordate characters, dorsal hollow nerve cord, pharyngeal gill slits, and notochord. In previously Branchiostoma (=Amphioxus) was placed under Mollusca but later it was placed under Subphylum Chephalochordata, which is … Read more