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 upcoming discussion will update you about the differences between Cartilaginous and Bony Fishes. Difference # Cartilaginous Fishes: 1. Cartilaginous fishes are mostly marine. 2. The mouth of cartilaginous fishes is ventral. 3. The external nares are ventral. 4. The scales of cartilaginous fishes are Placoid. 5. In cartilaginous fishes, operculum is absent except chimaera. 6. Caudal fins are heterocercal [...]
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 [...]