232
C. M. YONOE
account of reefs and cays off British Honduras with a preliminary
account of re-survey following the major hurricane of 1961. Over a
stretch of some 5 miles north of the storm centre he found that 80% of
the reef corals had disappeared while the summits of patch reefs were
denuded of living coral. Even the groove-buttress system had been
completely destroyed for 10 miles. The only surviving corals in the most
devastated areas were massive forms, notably Hd&rea annztlaris,
already noted as the most important reef-builder amongst Atlantic
corals (Goreau, 1969b).*
VIII. PHYsIoLoaY
Recent increase in knowledge about the physiology of corals has
been largely confined to the notable work of Goreau on calcification and
growth. The influence on this of the zooxanthellae demands prior
deseription of the important recent work on these symbionts. Them
has been no further study of feeding, digestion, respiration or excretion
since that carried out by the Great Barrier Reef Expedition (Yonge,
1930-31) and by the Palao Tropical Biological Station.
From that laboratory Kawaguti (1944b) has given an account of the
pigments in various hermatypic corals. While the zooxanthellae (in the
endoderm) provide a brown background, there is a wide range of
pigments-green fluorescent, pink, purple, vermilion, yellow and
white-in the ectoderm. The first probably serves as a protective light
filter which could be the function of others. Pigments in the ahermatypic Dendrophyllia and Balanoph yllia occur in both ectoderm and
endoderm and are different.
Horridge (1957) studied co-ordination of protective retraction in
various Scleractinia and Octocorallia. Responses to electrical sthuhtion in individual polyps, best seen in Fungia, resemble those in Actiniaria. I n colonial genera, repeated stimulation may never, aein ( I r o n i u p ~ ~
and Porites, affect more than a local group of po!yps or may eventually
cause retraction of polyps throughout the entire colony.
IX. ZOOXANTHELLAE
A. Nature
Unicellular zooxanthellae are invariably present, usually, although
not quite exclusively, confined to the endoderm, in all hermatypic
corals. They lie within a type of wandering or carrier cell (see Goreau,
1961a, Fig. 8). They are normally present in the extruded p l a n u b
although, according to Atoda (1951a) not necessarily so in Acrqpora
*In the course of recent correspondence, the writer hes been informed by Dr. aOreeu
that boring qmnges are major agents of erosion on W e s t Indian reefs.
C. M. YONOE
account of reefs and cays off British Honduras with a preliminary
account of re-survey following the major hurricane of 1961. Over a
stretch of some 5 miles north of the storm centre he found that 80% of
the reef corals had disappeared while the summits of patch reefs were
denuded of living coral. Even the groove-buttress system had been
completely destroyed for 10 miles. The only surviving corals in the most
devastated areas were massive forms, notably Hd&rea annztlaris,
already noted as the most important reef-builder amongst Atlantic
corals (Goreau, 1969b).*
VIII. PHYsIoLoaY
Recent increase in knowledge about the physiology of corals has
been largely confined to the notable work of Goreau on calcification and
growth. The influence on this of the zooxanthellae demands prior
deseription of the important recent work on these symbionts. Them
has been no further study of feeding, digestion, respiration or excretion
since that carried out by the Great Barrier Reef Expedition (Yonge,
1930-31) and by the Palao Tropical Biological Station.
From that laboratory Kawaguti (1944b) has given an account of the
pigments in various hermatypic corals. While the zooxanthellae (in the
endoderm) provide a brown background, there is a wide range of
pigments-green fluorescent, pink, purple, vermilion, yellow and
white-in the ectoderm. The first probably serves as a protective light
filter which could be the function of others. Pigments in the ahermatypic Dendrophyllia and Balanoph yllia occur in both ectoderm and
endoderm and are different.
Horridge (1957) studied co-ordination of protective retraction in
various Scleractinia and Octocorallia. Responses to electrical sthuhtion in individual polyps, best seen in Fungia, resemble those in Actiniaria. I n colonial genera, repeated stimulation may never, aein ( I r o n i u p ~ ~
and Porites, affect more than a local group of po!yps or may eventually
cause retraction of polyps throughout the entire colony.
IX. ZOOXANTHELLAE
A. Nature
Unicellular zooxanthellae are invariably present, usually, although
not quite exclusively, confined to the endoderm, in all hermatypic
corals. They lie within a type of wandering or carrier cell (see Goreau,
1961a, Fig. 8). They are normally present in the extruded p l a n u b
although, according to Atoda (1951a) not necessarily so in Acrqpora
*In the course of recent correspondence, the writer hes been informed by Dr. aOreeu
that boring qmnges are major agents of erosion on W e s t Indian reefs.