The surface zone has the ocean's least dense water and represents approximately 2% of the total volume of ocean water. The surface zone usually ranges between depths of 500 feet to 3,300 feet below ocean surface, but this can vary a great deal.
A hypha (plural hyphae, from Greek á½ÏÎ®, huphá¸, âwebâ) is a long, branching filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Yeasts are unicellular fungi that do not grow as hyphae.
The primitive streak is a structure that forms in the blastula during the early stages of avian, reptilian and mammalian embryonic development.The presence of the primitive streak will establish bilateral symmetry, determine the site of gastrulation and initiate germ layer formation.he formation of the primitive streak in the blastocyst involves the coordinated movement and re-arrangement of cells in the epiblast. Even before the streak is visible, epiblast cells have started to move. Two counter-rotating flows of cells meet at the posterior end, where the streak forms.