Phase-Shift Dynamics of Sea Urchin Overgrazing on Nutrified Reefs

Phase-Shift Dynamics of Sea Urchin Overgrazing on Nutrified Reefs

Shifts from productive kelp beds to impoverished sea urchin barrens occur globally and represent a wholesale change to the ecology of sub-tidal temperate reefs. Although the theory of shifts between alternative stable states is well advanced, there are few field studies detailing the dynamics of these kinds of transitions. In this study, sea urchin herbivory (a 'top-down' driver of ecosystems) ...

Laboratory on sea urchin fertilization.

Since about 1880, the eggs and sperm of sea urchins have been used for the study of fertilization, the metabolic activation of development and gene regulatory mechanisms governing embryogenesis. Sea urchin gametes are a favorite material for observations of the process of fertilization in advanced high school, community college, and university biology laboratory courses. This article is a labor...

Dynamics of thin filopodia during sea urchin gastrulation.

At gastrulation in the sea urchin embryo, a dramatic rearrangement of cells establishes the three germ layers of the organism. Experiments have revealed a number of cell interactions at this stage that transfer patterning information from cell to cell. Of particular significance, primary mesenchyme cells, which are responsible for production of the embryonic skeleton, have been shown to obtain ...

Sea urchin recovery from mass mortality: new hope for Caribbean coral reefs?

C reefs are often referred to as the rainforests of the sea, although, as Davidson (1) points out, one could equally well call rainforests the coral reefs of the land. Regardless, these two ecosystems do indeed share several important attributes, most notably high diversity and severe declines worldwide over the last several decades. There are many differences, however, between reefs and rainfo...

Membrane and lipid dynamics at fertilization in sea urchin eggs