Embryonic pressure tolerancesof bathyal and littoral echinoids from the tropical Atlantic and Pacific oceans.

Embryos of 10 species of tropical echinoids, including 5 littoral species from Hawaii, 2 littoral
species from the Bahamas, and 3 bathyal species from the Bahamas, were incubated at pressures as high as 300
atm to detennine if pressure tolerances could explain the observed limits of bathymetric distribution. In every case,
embryos were able to tolerate pressures found far outside their normal distributional ranges. Bathyal species
sometimes had narrower pressure tolerances than littoral species. It appears that pressure does not set actual limits
of most species and would not prevent recruitment or invasion of depths as great as 2000m.