THE BIOLOGY OF CORAL REEFS
215
Sckractinia (Wells, 1956) in the “ Treatise on Invertebrate Paleontology”. These deal with structure (notably of the skeleton), physiology,
ecology and distribution of corals. Both vertically and horizontally,
starting from shallow mid-tropical waters, hermatypic corals diminish
in numbers, giving place eventually to ahermatypic species. The
probable course of evolution, in terms of skeletal elaboration, is outlined, but the difference in the sequence of development of organs and
skeletal parts noted by Atoda (1953) may also be relevant here. It
would also be illuminating if skeletal changes could be related to
greater efficiency and wider powers of adaptation. Modern corals are
highly adapted for life in the many different environments present on
modern reefs and also for capturing zooplankton of all sizes. The form
of the skeleton plays its part in these adaptations.
Knowledge of the coral fauna of the Eastern Pacific, from the Gulf
of California, the Galapagos and other offshore islands, has been greatly
extended by the work of Durham (1947, 1962), Durham and Barnard
(1952), Hertlein and Emerson (1957), Squires (1959) and Durham and
Allison (1960). Although apparently somewhat modified by later work,
Durham and Barnsrd list a coral fauna of ninety-eight species representing thirty-nine genera. Although twenty-seven of these species
are hermatypic, conditions, largely of temperature, prevent the formation of reefs. In a very full description of the recent (and also
Pleistocene and Pliocene) coral fauna of the Gulf of California, Squires
(1959) notes the gradual impoverishment going north. A southern
fauna consisting of species of Pavona, Pocillopora and Porites loses first
the species of Pavona and then of Pocillopora and finally those of
Poritee, which give place to kelp in the northernmost and coldest waters
of the Gulf. Squires also notes that tho coral fauna of the ewitern
Pacific has little affinity with that of the WeHt Indian region, being
essentially Indo-Pacific. The effect of Ekmau’s Eastern Pacific Barrier
is negligible, at any rate for scleractinians, the more hardy of which are
distributed over the entire width of the Pacific. The major recent
contributions to coral systematics by Bowhma, one of tho most
distinguished of modern workers on corals, are a scries of papers
(1948a, b, 1949, 1950, 1951) on the Hydrocorallia (not a xystematic unit
but a convenient term covering the very different Milleporina and
Stylaaterina formerly grouped togethcr in thc Hydrocorallinae). AH
discussed below, he has made a major coiltrihution to tho HpecieH
problem in Millepora, deciding that infitead of the one fipecieH nuggf!~t,cd
by Hickson, there are at least ten.
Major collections of corals from two of the richest area8 in the world,
the Great Barrier Reef of Australia and the Marfihall WartdrJ, hnvc! heen
215
Sckractinia (Wells, 1956) in the “ Treatise on Invertebrate Paleontology”. These deal with structure (notably of the skeleton), physiology,
ecology and distribution of corals. Both vertically and horizontally,
starting from shallow mid-tropical waters, hermatypic corals diminish
in numbers, giving place eventually to ahermatypic species. The
probable course of evolution, in terms of skeletal elaboration, is outlined, but the difference in the sequence of development of organs and
skeletal parts noted by Atoda (1953) may also be relevant here. It
would also be illuminating if skeletal changes could be related to
greater efficiency and wider powers of adaptation. Modern corals are
highly adapted for life in the many different environments present on
modern reefs and also for capturing zooplankton of all sizes. The form
of the skeleton plays its part in these adaptations.
Knowledge of the coral fauna of the Eastern Pacific, from the Gulf
of California, the Galapagos and other offshore islands, has been greatly
extended by the work of Durham (1947, 1962), Durham and Barnard
(1952), Hertlein and Emerson (1957), Squires (1959) and Durham and
Allison (1960). Although apparently somewhat modified by later work,
Durham and Barnsrd list a coral fauna of ninety-eight species representing thirty-nine genera. Although twenty-seven of these species
are hermatypic, conditions, largely of temperature, prevent the formation of reefs. In a very full description of the recent (and also
Pleistocene and Pliocene) coral fauna of the Gulf of California, Squires
(1959) notes the gradual impoverishment going north. A southern
fauna consisting of species of Pavona, Pocillopora and Porites loses first
the species of Pavona and then of Pocillopora and finally those of
Poritee, which give place to kelp in the northernmost and coldest waters
of the Gulf. Squires also notes that tho coral fauna of the ewitern
Pacific has little affinity with that of the WeHt Indian region, being
essentially Indo-Pacific. The effect of Ekmau’s Eastern Pacific Barrier
is negligible, at any rate for scleractinians, the more hardy of which are
distributed over the entire width of the Pacific. The major recent
contributions to coral systematics by Bowhma, one of tho most
distinguished of modern workers on corals, are a scries of papers
(1948a, b, 1949, 1950, 1951) on the Hydrocorallia (not a xystematic unit
but a convenient term covering the very different Milleporina and
Stylaaterina formerly grouped togethcr in thc Hydrocorallinae). AH
discussed below, he has made a major coiltrihution to tho HpecieH
problem in Millepora, deciding that infitead of the one fipecieH nuggf!~t,cd
by Hickson, there are at least ten.
Major collections of corals from two of the richest area8 in the world,
the Great Barrier Reef of Australia and the Marfihall WartdrJ, hnvc! heen