THE BIOLOGY OF CORAL REEFS
219
Galaxea aspera and Seriatopora hystrix and also (1951d) asexual
reproduction in the Seriatoporidae. Planulation occurs throughout the
year and in all except Acropora brwgemanni in relation to some phase
of the moon (a condition already known in some other corals). Although
usually settling quickly, planulae can remain swimming for a considerable period. He confirmed and extended the observations of
Edmondson that darkness delays settlement and found that it also
retards subsequent development. With suitable facilities such studies
could be greatly extended.
Factors governing settlement, including the nature of the substratum and aggregation, are of prime importance for sedentary
animals. They have been extensively studied in temperate waters,
notably in connexion with acorn barnacles, with Spirorbis and with
species of Ostrea and Crassostrea. In corals there is the added problem
of the effect of aggregation on the formation of compound colonies.
There is also the later loss of attachment in certain genera and species,
in the Indo-Pacific fungids and in the Atlantic maeandrine Hanicina
areolata, and in the ahermatypic Turbinoliinae which are adapted for
life on an unstable substratum which, as noted by Vaughan and Wells
(1943), gives little surface for settlement of the planulae.
V. ECOLOQY OF AroLLs
The major contribution to the classic coral reef problem since World
War I1 has come from the extensive United States investigations in the
Marshall and Caroline Islands. Many atolls, notably Bikini and
Eniwetok, have been examined in grc?rA c,c:c?ariop;raphioal, gwhgioal
and geographical detail. The major h ~ J l f J ~ i f : d
wrm kri6vc l w m dt:dy
defined. A comprehensive account of all tqect8 of thiR, extending of
course to land flora and fauna and every aqmt of human habitation,
has recently been made by Wiens (1962) who has himself made notable
contributions in the geographical field. These investigations may be
said to have culminated in the final boring on Eniwetok where basalt
waa encountered at 4630 ft, the deepest coral being of late Eocene
formation (Ladd et al., 1953). The atoll is revealed as resting on a
truncated volcano possibly similar in nature to the numerous sea mounts
or guyots present in thc north-west Pacific (Hamilton, 1956). Certainly
to the east of the andesitc line which represente the wcHtcrn limit of tho
Pacific basin, Darwin’s view8 appear triumphtlntly juRtificd. To the
west of the line where thcrc iH uxterwive clevation, aH at ‘I’orqp rmd
Fiji, the coursc of rccf formution must have hocn different.
The initial rcsult of thcsc survoys has boon to confirm and oxtond
219
Galaxea aspera and Seriatopora hystrix and also (1951d) asexual
reproduction in the Seriatoporidae. Planulation occurs throughout the
year and in all except Acropora brwgemanni in relation to some phase
of the moon (a condition already known in some other corals). Although
usually settling quickly, planulae can remain swimming for a considerable period. He confirmed and extended the observations of
Edmondson that darkness delays settlement and found that it also
retards subsequent development. With suitable facilities such studies
could be greatly extended.
Factors governing settlement, including the nature of the substratum and aggregation, are of prime importance for sedentary
animals. They have been extensively studied in temperate waters,
notably in connexion with acorn barnacles, with Spirorbis and with
species of Ostrea and Crassostrea. In corals there is the added problem
of the effect of aggregation on the formation of compound colonies.
There is also the later loss of attachment in certain genera and species,
in the Indo-Pacific fungids and in the Atlantic maeandrine Hanicina
areolata, and in the ahermatypic Turbinoliinae which are adapted for
life on an unstable substratum which, as noted by Vaughan and Wells
(1943), gives little surface for settlement of the planulae.
V. ECOLOQY OF AroLLs
The major contribution to the classic coral reef problem since World
War I1 has come from the extensive United States investigations in the
Marshall and Caroline Islands. Many atolls, notably Bikini and
Eniwetok, have been examined in grc?rA c,c:c?ariop;raphioal, gwhgioal
and geographical detail. The major h ~ J l f J ~ i f : d
wrm kri6vc l w m dt:dy
defined. A comprehensive account of all tqect8 of thiR, extending of
course to land flora and fauna and every aqmt of human habitation,
has recently been made by Wiens (1962) who has himself made notable
contributions in the geographical field. These investigations may be
said to have culminated in the final boring on Eniwetok where basalt
waa encountered at 4630 ft, the deepest coral being of late Eocene
formation (Ladd et al., 1953). The atoll is revealed as resting on a
truncated volcano possibly similar in nature to the numerous sea mounts
or guyots present in thc north-west Pacific (Hamilton, 1956). Certainly
to the east of the andesitc line which represente the wcHtcrn limit of tho
Pacific basin, Darwin’s view8 appear triumphtlntly juRtificd. To the
west of the line where thcrc iH uxterwive clevation, aH at ‘I’orqp rmd
Fiji, the coursc of rccf formution must have hocn different.
The initial rcsult of thcsc survoys has boon to confirm and oxtond