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Before gastrulation, the embryo is a continuous epithelial sheet of cells; by the end of gastrulation, the embryo has begun differentiation to establish distinct cell lineages, set up the basic axes of the body (e.g. dorsal–ventral, anterior–posterior), and internalized one or more cell types including the prospective gut.
During gastrulation cells migrate to the interior of the blastula, subsequently forming two (in diploblastic animals) or three (triploblastic) germ layers. The embryo during this process is called a gastrula. The germ layers are referred to as the ectoderm, mesoderm and endoderm.
The process of the oversupply of nutrients leading to algae growth and oxygen depletion is called eutrophication. Algal and bacterial blooms have persistently contributed to mass extinctions driven by global warming in the geologic past, such as during the end-Permian extinction driven by Siberian Traps volcanism and the biotic recovery ...
Fish embryos go through a process called mid-blastula transition which is observed around the tenth cell division in some fish species. Once zygotic gene transcription starts, slow cell division begins and cell movements are observable. [4] During this time three cell populations become distinguished. The first population is the yolk syncytial ...
Epiboly in zebrafish is the first coordinated cell movement, beginning at the dome stage late in the blastula period and continuing throughout gastrulation. [3] At this point the zebrafish embryo contains three portions: an epithelial monolayer known as the enveloping layer (EVL), a yolk syncytial layer (YSL) which is a membrane-enclosed group of nuclei that lie on top of the yolk cell, and ...
A red tide occurs because dinoflagellates are able to reproduce rapidly and copiously as a result of the abundant nutrients in the water. Although the resulting red waves are an interesting visual phenomenon, they contain toxins that not only affect all marine life in the ocean, but the people who consume them as well. [ 75 ]
The Florida red tide organism, known as K. brevis, produces brevetoxins that can affect the central nervous system of fish and other vertebrates, causing these animals to die.
The primary source of revenue generation in many of the communities affected by K. brevis red tides is tourism. During periods of red tides this important source of revenue is often lost to the impacted coastal communities of Florida, often on the scale of tens of millions of dollars. [18] This particular protist is known to be harmful to ...