230
C. M. YONOE
solution and of organic agencies in the formation of the characteristio
intertidal “ nick ”.
We can here only concern ourselves with boring organisms, about
which there is still very much to be learnt. Effeotively nothing is known
about the effect of the filamentous green algae invariably found BB 8
green zone some distance within the surface of living coral oolonies.
Ramon (1955) notes the importance of the blue-green algae HyeUa sp.
and Ostreobium sp. which live on and just within the surface of coral
rock while he also considers that Porolithon does not merely grow over
but actually dissolves its way into underlying dead coral rock.
Thanks no doubt to the presence of nematocysts, corals are little
affected by predators. I n the West Indies, Marsden (1962) describes
the activities of a coral-eating amphinomid polychaete, H e m m d h
curunculata, which crawls over Porites porites when it is expanded at
night. It eats the polyps, fragments of which with nematocysts and
zooxanthellae are found in the gut. The skeleton is presumably not
affected and the tissues doubtless soon regenerate. A variety of parrot
fishes (Scaridae) and file fishes (Monacanthidae) scrape or nibble living
corals according to Motoda (1940b), Schultz (1948) and Bardach (1961).
The latter estimated the amount, and discussed the probable importance, of the calcareous matter which passes through the gut of these
omnivorous browsing fishes.
Although nematocysts protect living coral, the dead skeleton is
penetrated by many organisms. Studies on Raroia by Doty and
Morrison (1954) and Newell (1950) stress the significance there of bluegreen algae which cover the intertidal rock surface and, poseibly, of
the deeper penetrating algal filaments. Together they consider these
form the food of a series of gastropods which occupy very definite
zones in the intertidal and supralittoral, in the order, from above
downwards : Melaraphe - Tectarius -iVerita - ThaM/Morula - Turbo.
Of these, Thais and Morula are neogastropoda and will be carnivorous,
but the remainder, members of the Archaeogastropoda and Neritacsa
and so primarily herbivorous, doubtless scrape deeply with the radub
into the rock which has previously been softened chemically by the
algae. In the Atlantic, Newell and Imbrie (1955) found similar snaitils
grazing in the intertidal “ nick ”.
A notable assemblage of animals bore deeply into the rock, including
sipunculids (about which very little is known) and boring barnacles of
the genus Lithotrya. Between them, Newell and Imbrie considered these
worms and barnacles remove ‘‘ aa much as 50% of the rock substance
in the intertidal nick ” at Bimini. Umbgrove (1947) noted the importance of the urchin Echinometra mathaei in the same region in the
C. M. YONOE
solution and of organic agencies in the formation of the characteristio
intertidal “ nick ”.
We can here only concern ourselves with boring organisms, about
which there is still very much to be learnt. Effeotively nothing is known
about the effect of the filamentous green algae invariably found BB 8
green zone some distance within the surface of living coral oolonies.
Ramon (1955) notes the importance of the blue-green algae HyeUa sp.
and Ostreobium sp. which live on and just within the surface of coral
rock while he also considers that Porolithon does not merely grow over
but actually dissolves its way into underlying dead coral rock.
Thanks no doubt to the presence of nematocysts, corals are little
affected by predators. I n the West Indies, Marsden (1962) describes
the activities of a coral-eating amphinomid polychaete, H e m m d h
curunculata, which crawls over Porites porites when it is expanded at
night. It eats the polyps, fragments of which with nematocysts and
zooxanthellae are found in the gut. The skeleton is presumably not
affected and the tissues doubtless soon regenerate. A variety of parrot
fishes (Scaridae) and file fishes (Monacanthidae) scrape or nibble living
corals according to Motoda (1940b), Schultz (1948) and Bardach (1961).
The latter estimated the amount, and discussed the probable importance, of the calcareous matter which passes through the gut of these
omnivorous browsing fishes.
Although nematocysts protect living coral, the dead skeleton is
penetrated by many organisms. Studies on Raroia by Doty and
Morrison (1954) and Newell (1950) stress the significance there of bluegreen algae which cover the intertidal rock surface and, poseibly, of
the deeper penetrating algal filaments. Together they consider these
form the food of a series of gastropods which occupy very definite
zones in the intertidal and supralittoral, in the order, from above
downwards : Melaraphe - Tectarius -iVerita - ThaM/Morula - Turbo.
Of these, Thais and Morula are neogastropoda and will be carnivorous,
but the remainder, members of the Archaeogastropoda and Neritacsa
and so primarily herbivorous, doubtless scrape deeply with the radub
into the rock which has previously been softened chemically by the
algae. In the Atlantic, Newell and Imbrie (1955) found similar snaitils
grazing in the intertidal “ nick ”.
A notable assemblage of animals bore deeply into the rock, including
sipunculids (about which very little is known) and boring barnacles of
the genus Lithotrya. Between them, Newell and Imbrie considered these
worms and barnacles remove ‘‘ aa much as 50% of the rock substance
in the intertidal nick ” at Bimini. Umbgrove (1947) noted the importance of the urchin Echinometra mathaei in the same region in the