Using a global data set on egg hatch times in zooplanktonic and nektonic ectotherms
from marine waters, the combined effects of body size, temperature and life-history attributes on
development times were examined. After correcting for mass and temperature the mean egg hatch
times (from laying to hatching) were 20 times faster in some taxa than in others. Some of the divergence
in hatch times can be accounted for by the disposition strategy of the eggs. Eggs that are protected
after laying (e.g. carried by the female, or attached to a substrate or floating in clumped
masses) take 3.3 times longer on average to develop to hatching than those spawned individually and
freely into the pelagic environment (i.e. ‘unprotected’), and this difference is independent of egg size.
Given that unprotected eggs typically have higher mortality rates, it is proposed that evolution has
acted to shorten this vulnerable period. Not only do hatch times appear to diverge on the basis of egg
protection strategy, but also a similar degree of separation was apparent in cell cycle duration (i.e.
time from 2 to 4 cell stage). These results reinforce the importance of egg disposition on development
rate processes and their evolution.