For an individual fish, the beginning of development
is fertilisation of the egg by spermpatozoa. Most marine
teleosts have pelagic eggs which drift with the plankton
in a ll water layer between the surface and the bottom
However, fishes like the British herring
and Blennier and Gobier have demersal eggs, which attach
to substrata like stones, shells and weeds. Usually,
pelagic eggs are transparent and spherical, with the
exception of the eggs of certain engraulids t o l e v h o r u s
which are oblong. When the embryo is fully developed, '
&t hatches out as larva and undergoes further development,
Fertilisation end Embryonic developmen
