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
Characteristics Features of Subphylum Urochordata: They live in marine water, almost present in all part of the world and in deep ocean as well as in shallow coastal areas. They can live in solitary state, sometimes large number of Urochordate live in groups in solitary state, some of them show colonial form. They are generally … Read more
Ascidia: It is solitary Urochordate generally live in groups on the rocks, it presents in sedentary state and lives in all depth of the ocean, have great similarity with Herdmania. Size is more than other Urochordate as compared to other members of Subphylum Urochordata, around 10 cm to 15 cm long. It is cylindrical in … Read more
As examples of Subphylum Urochordata, we will discuss some Urochordata genus, their general characteristics features, Clavellina, Salpa, Botryllus, Ascidia, Ciona, Molgula, Pyrosoma, Doliolum, Oikopleura, Ciona. Clavellina: Examples of Subphylum Urochordata: Clavellina is a colonial Urochordate, generally observed in shallow coastal areas attached to the rock. The individual zooids are connected to the colony with the … Read more
Subphylum Urochordata has more than 2000 species and have different characters, based on the similarities and dissimilarity different workers tried to divide them in different ways. But here we will not discuss all the classification approaches of all workers, we only discuss the most adopted classification scheme of subphylum Urochordata by Storer and Usinger. According … Read more