The following points highlight the two types of eggs. The types are: 1. Eggs Based on Quantity of Yolk 2. Eggs Based on Distribution of Yolk in Cytoplasm. Type # 1. Eggs Based on Quantity of Yolk: 1. Microlecithal Eggs: They contain very small amount of yolk, e.g. eggs of Sea urchin, Herdmania, amphioxus. The eggs of man contain very [...]
The below mentioned article provides biology notes on Eucoelomates. The animals which possess true coelom are called eucoelomates or coelomates. The true eucoelomates is a body cavity which arises as a cavity in embryonic mesoderm. In this case, the mesoderm of the embryo provides a cellular lining, called coelomic epithelium or peritoneum, to the cavity. The eucoelomates is filled with [...]
The below mentioned article provides biology notes on Phylum Hemichordata. (Gk. hemi- half, chordate- notochord) Due to some similarities with chordates, some workers considered Hemichordata as a subphylum under phylum chordata. But, on grounds of its general organization, recent scientists, like Vander Horst (1939), Dawyd off (1948), Marcus (1958) and Hyman (1959), have given it the status of a phylum [...]