GREATBARRIER REEF MARINE PARK AUTHORITY
I
TEzHN1cALMEMoRANDuMGBRMF!Aa-11
-mORNS
STARFISH(-IPLBNCI
(L))
P.D. WALBRAN
Febrmry, 1887
(Sulxnitted titober 1984)
Geology Department, James Cook Ibiversity
of North aeensland
Tomsville,
meensland 4811, Australia
In recent years extensive damage has been caused to many reefs in
the Great Barrier
Reef canplex by the crown-ofthorns
starfish
(A. planci).
Authors on the subject are divided as to whether
the outbreaks are a recurring natural phenanenon or a result of
the influence
of man.
'lbe identification
of crow-ofthorns
skeletal-rich
zones in reef sediment and cores may help to
determine if large poplation
fluctuations
occurred prior to the
arrival of Europeans in central meensland.
An atlas of crown-opthorns
skeletal caqonents has been canpiled
to assist
in the identification
of these parts.
The atlas
features representative
examples of each of the separate skeletal
series present in A. planci and discusses skeletal architecture,
glossmoqhology,
mXcl.ostructure,
and the recognition
of elements
in the sedimentary record.
In addition,
the atlas canpares
skeletal
elements of A. planci with similar
elements fran four
other stars canmon onThe Great Barrier Reef and concludes that
they are readily distinguished.
KEYWtJRIB: Acanthaster,
GBR,
microstrwture,
sedimentary record, skeletal architecture.
mor&ology,
Technical menoranda are of a preliminary
nature, and represent
the views of the author, not necessarily
those of the Great
l%.rrier Reef Marine Pwk Authority.
Please address ccmments or requests
for additional
copies to:
Ihe Executive Qfficer,
Great Wrier
F4eef Marine Rmk Authority,
P.O. Box 1379 TtHISVILLF, AWWLIA,
Q4810.
c Commonuealth of Australia
ISSN 0817-6094
ISBN 0-642-52641~
Published
Printed
by the GBRMPA,Tomsville
by the JCUNQ, Tomsville
1.
2.
3.
4.
5.
6.
7.
8.
Introdwtion
Previous literature
on the mor&ology of A. planci
Materials and methods
~rFhology
1. Skeletal Architecture
Characterisation
of individml
elemats
1. Gross morphology
2.Microstructure
3. Chanistry
Recognition of A'. planci in the sedimtxtary
record
Conclusion
References
Appendix - plates
1
2
3
4
7
11
13
14
16
LIST Op FIGURES
Eigure 1.
Schenatic section thrwgh the arm of A. planci
showing the relative
position of elem&ts.
5
Figure 2.
Arran&enent of elemeslts in the arm of A. planci.
6
LISTOFPL&l!M
Plate
Plate
Plate
Plate
Plate
Plate
Plate
Plate
Plate
Plate
Plate
Plate
Plate
1.
2.
Anatany of A. planci.
Anatany of K. planci continued.
'lkrminology~used in description
of ossicles.
3. A. Planci - element mor*ology.
4. 8. planci - element mor*ology
continued.
5. K. planci - eleinmt morphology continwd.
6. B. planci - elemat mor*olcgy
continued.
7. K. planci - element mor*ology
continti.
8. K. planci - elemmt morplology continued.
9. X. planci - mic~strwtureofelem~ts.
of elements continwd.
10. K. planci - microstructure
microstructure
of elements continued.
11. H. planci12. &her sea stars - elemmt mor*ology.
13. Other sea stars - microstru=tureofelements.
17
19
21
23
25
27
29
31
33
35
37
39
41
-l-
1.
-1ON
Within the last 25 years, large aggregations of Acanthaster
planci kave been report&
on 135 reefs of the Great Barrier Reef
from Iiilder Reef, north-east of Cooktown to lady Mxgrave Island,
east of Gladstone (Great E3arrier Reef &wine Rxrk Authority,
Several hundred thousand croun-ofthorns
starfish
may
1934).
invade a reef at any one time, resulting
in the almost total
destruction
of living
hard corals (Endean, 1982; Moran, lCB4).
Since the starfish
were first
observed in abnormally high nunbers
on Green Island in 1962 (Ewnes and &dean, X%4), the threat of
.&. planci to the reef system has been a constant concern.
The reason(s) for these apparently
recent infestations
of
the crown-ofthorns
is not understood.
Numerous hypotheses have
been put forward to account for these outbreaks.
Some authors
(for exsnple Ihna, 1970; Newnan, 1970; Frankel, 1975, 1977, 1978;
Vine, 1973; Neuman and IZtna, 1974; Pearson, 1975; Moore, 1978)
believe that flwtuations
in A. planci ppulations
are a natural
phenanenon tiich
have occut%d in the past jwt
as they are
occurring
at present
and are regulated
by envirornwntal
pressures.
F'rankel (1977, 1978) estimated, fran skeletal debris
in sediment, that aggregations occur every 25Oto300 years.
In contrast,
another group of authors (for example Fischer,
lB9;
Chesher, 1970; Brown and Willey,
1972; Randall,
1972;
Chesher, 1970; l&dean, 1973, 1977, 19?32) consider the population
explosions to be induxd,
either directly
or indirectly,
by the
activities
of man, for example remwall of predators,
physical
modification
of the enviromnent,
influx
of pollutants
and/or
nutrients into the water.
An understanding of the causal factors which influence
the
size and pericdicity
of starfish
outbreaks is fundamental in
determining the measures undertaken by goverwents and govermnent
agencies in managenent of these population explosions.
The identification
of A. planci lrkeletal
debris in zones within reefal
sediment and/oFdrill
cores may reveal aggregations or infestations prior to the arrival of white man in central @eensland and
thus help to determine whether these outbreaks are natural or
man-induced.
This atlas provides a photographic reference of some of the
more camnon and most likely
to be preserved skeletal canpxents
of A. planci,
as well as higher magnification
microstrwture
studxes, so that both dole and fragmentary elements may be identified
in sediment cores.
!Ihe skeletal
canponents of A. planci
are briefly
carqared to those of other sea stars cam6 on the
Great Barrier Reef.
-
2.
HlwIouS
LImm
m
Tmz -
2 -
OF A. PLANCI
hhdsen (1955) traced the history
of the genus Acanthaster
and can~.xred the moqhology of the IndeWest-Pacific
species,
to that of its Fast-Pacific
(Anerican)
relative,
A. planci,
on external features such
s. ellisii
(Gray, 1840), concentrating
% bodyaridth
to arm-length ratio,
ventral
and dorsal spines,
pedicillariae
and mouth plates.
C&o (1961) al=
canpared the external
morplologies
of
A. planci
and A. ellisii,
enqhasising,
as Madsen did,
the
$ortance
of sp%es, pedicillariae
and mouth (bucal) plates in
distinguishing
the two.
She also named a new subspecies,
A. ellisii
pseudoplanci.
In her 1970 paper, Caso confined her
description
solely to that of A. planci, once again concentrating
on spines, pedicellariae
and the bmal plates.
Blake (1979) described,
or mentioned, most of the skeletal
elements present in A. planci in his ccnqarison of A. planci with
members of the GreasFeridae and the Ezhinasteridae.According to
Blake, the marginal ossicle series is "the key to the interpretation of these and other ossicle series" as the other series, i.e.
the actinals
and the abactinals,
are recognised according to
their position
relative
to the marginals.
The terminology used
by Blake was found to be satisfactory
during the present study
and has been retained wherever possible.
For definitions
of
terms used the reader is referred to Spencer and Wright (1336).
I
-
3
-
Chm-ofthorns
starfish
were collected on John Ekewzr Reef,
7Okm nortkeas-t
of Tov,nsville,
Queensland.
The individml
exaMned ws a 19-axned specimen of 35cmdiameter.
The flesh was dissolved
in 'Wolwrths'
brand household
liquid bleach - active ingredient
sodium hypochloride
(available
chlorine 4% w/v).
Skeletal elements uere rinsed in tap water and
oven dried.
Individwl
elements were then gold plated and
examined and photographed on a scanning electron micxxxcope.
An
electron
micrx3probe analysis
of ossicles
wds carried out to
determine mole % MgQ3.
-4-
4.
-
4.1
Skeletal
Architecture
As stated by Blake (1979), the key to distinguishing
the
different
oesicle series is determined by their position relative
to the dotile
row of marginal ossicles
(Figure 1).
Elements
which lie ventral
to the marginals
are actinal
whilst
those
situated dorsally are abactinal.
Globose,
actinal
spine-hearing
intermediate
ossicles
(Figures 1, 2; Plate 1, Number 2) are.pesent
in revs of three to
four elements for most of the length of the arm, forming 'actinal
fields'
(Blake, 1979). The innermost actinal ossicles laterally
abut the adambulacral ossicles (Figures 1, 2; Plate 1, Number 2)
which sit sub-ventrally
on the ambulacral ossicles (Figures 1, 2;
Plate 1, Numbers la, lb).
The adambulacralsand
ambulacralsline
the ambulacral furrow (Figure 1; Plate 1, Number lb) poviding
support and protection
for the radial canals and tube feet of the
The arms terminate distally
in a single
water vascular system.
arm-tip ossicle,
the terminal (Blake, 1979).
Within the ambulacral series, the first
ambulacral ossicle,
which is situated adjacent to the body cavity,
is the largest
Ventral to the first
ambulacral
(Figure 2; Plate 1, Number 4).
ossicle,
the oral (mouth-angle)
ossicle terminates
the adambu'Ihe interbrachial
lacral series (Figure 2; Plate 1, Number 4).
ossicle sits in the arch formed between the first
ambulacral and
oral ossicles (Figure 2; Plate 1, Numbers 3, 4). Its function is
to space the proximal ossicles of adjacent arms and serve as the
basal support to the series of the interbrachial
plates (Figure
2; Plate 1, Number 3).
The primary and secondary abactinal ossicles form a meshwork
of dental elements over the dorsal surface of the anns'and disc.
Plateand rod-&aped
secondary abactinal
ossicles
provide
support for the larger spinebearing
primary abactinal
ossicles
(Figure 1; Plate 2, Numbers 1, 2).
The crown-ofthorns
starfish
is covered with a largenunber
ofbluntandbarbed
spines.
Ventrally,
blunt spines are borne on
the adambulacral, actinal intermediate,
and oral oesicles (Figure
1; Plate 1, Numbers 2, 3).
On the dorsal surface, long barbed
and shorter un&bed spines are present on the primary and, uncawnonly, some secondary abactinal
ossicles respectively
(Figure
1; Plate 2, Number 1).
Bivalved pedicellariae
occur on the actinal
and abactinal
surfaces of A. planci.
Pedicellarial
pits are present in most,
but not all,- adambulacral ossicles
(Figure 1), whilst,
on the
abactinal
surface, pedicellariae
sit in pedicellarial
cups snbedded in the skin (Plate 1, Numbers 5, 6). Several madreporites
are al= embedded in the skin of the disc (Plate 1, Numbers 6,
7). These are supported by secondary abactinal ossicles.
Subspherical to elliptical
granules are found in the surface
layers of skin on the dorsal surface (Plate 1, Numbers 5-7).
Encrusting granules are abmdant in the sheath of skin covering
the actinal
intermediates,
primary abactinals,
and the basal
section of actinal and abactinal spines (Plate 1, Number 5).
-5Figure
1.
Schematic
the relative
1
Primary
abactinal
2
Secondary
abactinal
3
Abactinal
4
Marginal
5
Actinal
section
through
position
of
ossicle
the arm
elements.
of
6
Actinal
7
Pedicellaria
spine
8
Adambulacral
ossicles
9
Ambulacral
intermediate
ossicles
ossicles
10 Adambulacral
_A. planci
spines
ossicle
ossicle
furrow
showing
-6Figure
2.
Arrangement
1
Ambulacral
2
First
3
Interbrachial
4
Interbrachial
5
Oral
of
elements
ossicles
ambulacral
(mouth-angle)
in
the
arm
of A. planci.
6
Actinal
7
Pedicellaria
plates
8
Adambulacral
ossicle
9
Actinal
ossicle
ossicle
spines
ossicles
intermediate
ossicles
-
5.
ClIARA~sLATIOI?OF
5.1
Gross Mor@ology
Adambulacral
7 -
INDIVIDUAI,~EEHMTS
Ossicles
(Plate
3, Numbers l-5):
Adanbulacral
ossicles
are rectangular
elements with a
pronounced distal
abactinal
extension.
Well defined interadanbulacral mwle
depressions are present on both the distal
and
proximal surfaces (Plate 3, Numbers 5b, 5d).
Four subcircular
surfaces are present on
ambulacral - adambulacral articulation
the abactinal surface of each ossicle (Plate 2, Number 6).
!lko rows of spines, rmning parallel
to the adamabulacral
furrow, are borne on the adambulacrals (Figure 1). Spine bases
are snail,
rounded knolls
on the actinal
surface (Plate 2,
Number 6).
'lhe nunber of pedicellarial
pits per adambulacral
varies within any row from zero up to an observed maximun of
three (Plate 3, Numbers 2-5).
One or two pits per ossicle
is
most conmon.
The pits are located proximally
on the furrow
surface of the oesicles (Figure 2).
Adambulacral ossicles frcrn the arm tip (Plate 3, Numbers la,
lb) are of the same general shape as more proximal ossicles but
many of the characteristics
for example spine bases and pedicellarial pits, are less pronou~ed.
Ambulacral
Ossicles
(Plate
3, Numbers 6-9):
Ambulacral ossicles are elongate with a broad and tapering
adradial
portion
(Plate 2, Number 4).
lbe
ambulacral adsnbulacral articulation
surfaces are deep-set, wings (Plate 2,
Number 4) are broad and gently to moderately curved (Plate 3,
Number 6~).
'Ihe abactinal
surface is slightly
indented.
%o
distinctly
different
patterns
of
ambulacral - snbulacral
articulation
surfaces (Plate 2, Number 4) are present (Plate 3,
Numbers 6a, 7). Adambulacrals from the arm tip are very similar
to those more proximal (Plate 3, Numbers 8, 9).
First
Ambulacral
Ossicles
(Plate 4, Number 2):
The first ambulacral ossicle is one of the largest elements
in A. planci and is significantly
different
fran the previously
described
ambulacral
ossicle.
'Ibe first
ambulacral - first
mnbulacral articulation
surface (Plate 2, Number 5) varies considerably
between individml
elements.
A prcminent ridge runs
the length of the abactinal
surface (Plate 2, Number 5).
The
wings, so evident in other ambulacrals,
are greatly reduced. Two
first amhulacral - oral ossicle articulation
surfaces are present
(Plate 2, Number 5).
-8-
Oral (Moun+Angle)Ossicles
(Plate
4, Number 1):
!lhe largest
element in A. planci,
the oral ossicle,
is
characterised
by a prminent
tapering proximal tip with numerous
spine bases and a first
ambulacral articulation
bar (Plate 2,
The
oral
ossicle
bares
five
to
six
large, blmt
Number 3).
spines tomrds the oral cavity and four to six snail,
tapered
A
large
indentation
accamncdates
the
spines distally
(Figure 2).
first adambulacral ossicle (Plate 2, Number 3). 'hvo oral - first
ambulacral articulation
surfaces are pesent (Plate 2, Number 3).
Interbrachial
Ossicles
(Plate 4, Number 3):
A single anvil-&aped
ossicle sits, supported by tuo stout
stubs, betueen the arms in the arch formed by the first
ambulacral and oral ossicles.
The abactinal surface is angled sharply
to fit the first
interbrachial
plate (Plate 2, Number 9).
The
neck is shorter, but thicker than the body (Plate 2, Number 9).
Interbrachial
Plates
(Plate
2, Number 12):
These elements vary in size and shape but are alays
Articulation
surfaces are very shallowly
flattened
laterally.
angled and typically
ridged.
In general, each side of the plate
has one articulation
surface.
Actinal
Intermediate
Ossicles
(Plate 4, Numbers 4-9; Plate
7, Number 7):
Actinal intermediates
are variable in si= and shape but are
essentially
globose and spine-bearing.
'lhose adjacent to the
marginal ossicles (Plate 7, Number 7) tend to be larger and more
tapered than ossicles closer to the adambulacrals.
Articulation
surfaces and skin and/or muscle attachnent
scars are readily
apparent in this series (Plate 2, Number 10).
A notch is often
Present in the actinal intermediate
- actinal spine articulation
surface (Plate 4, Numbers 6, 7).
Marginal
Ossicles
(Plate
4, Number 10):
'hvo 1‘0~ of marginal ossicles
are present in the arms of
A. planci.
They may he enlarged, spin-baring
elements but are
more conmonly discoid in shape (Plate 4, Number 10).
Secondary Abactinal
Ossicles
(Plate 5, Numbers 7-10;
Plate 6, Numbers l-11):
Secondary abactinals
are highly variable
in size and form
but are generally rod- or plate-l%.
Those which are plateymay
resemble
interbrachial
plates.
Articulation
surfaces
are
more ccmmonly,
curve-ridged
(Plate 2,
straight-ridged
or,
Numbers 7, 8).
abactinals
Although
most
secondary
are
"spineless"
some (Plate 6, Number8) do bare snail,
unbarbed
spines.
Very little
morphological
difference
appears to exist
hetwzen the secondary abactinals
of the arms and those of the
disc.
~~
-9-
Primary Abactinal
The
narrow,
(Plate 7,
abactinals
abactinal
surfaces
abactinal
Ossicles
(Plate
7, Numbers l-6,
8-10):
most easily distinguished
primary abactinals
are long,
conical
ossicles
with
basal
articulation
surfaces
Numbers l-5, 9-10).
Less canmonly, houever, primary
into
the meshwxk of secondary
are incorpxated
&sicles
and have dorsal and/or ventral articulation
(Plate 7, Numbers 6, 8; Plate 2, Number 11).
PtdIIl~y
ossicles are always spin-baring.
Ahactinal
Spines (Plate 8, Numbers 2-3):
Abactinal spines are long and narrOw and taper syr1~1Mrical1y
to a sharp, barbed point.
They are borne on both primary and
secondary abactinal ossicles.
Those borne on secondary abactinal
ossicles are mtlch snaller
and insignificant
in number canpred
with spines borne on primary abactinals.
Abactinal spines are
circular
in cros&-section.
A basal bulge is often present (Plate
3, Number 2).
Colouration
is a uniform medium to dark mauve
cdnging to a pale mauve at the base.
Under binocular
microscope exsanination the frameuork
elozate
althozh
frequently
fine and fairly
indistinct.
Actinal
Spines (Plate
is
8, Numbers 1, 4-8):
The majority
of actinal
spines taper only slightly
alorg
their length to a blmt,
often gmoved, nxnded tip.
They are
flattened
in cmsssection,
and are very often indented towards
the tip on the side facing the distal part of the arm. (Plate 8,
Numbers 1, 4).
Spines borne on the actinal
intermediates
adjacent to the marginals may taper uniformly to a blmt point.
Very snail spines (Plate 8, Numbers 6, 8) line the admbulacral
furrow on adanbulacral ossicles and at the distal end of the oral
ossicle (figure 2).
Actinal
spines are variable
in colour,
ranging from pale
mauve to dark mauve and, rarely,
an intense orangered.
The
indented or distal
surface is darker in colour than that which
faces the body cavity and thus actinal
spines are readily dis
cernible fran abactinal spines.
In addition,
actinal spines may
contain a notch in their articulation
surface.
Under binocular
micmsco=
the
coarse, open and distinctly
elollgate.
Pedicellariae
ultrastrwture
appears
(Plate 8, Numbers 9-17):
Elongate and stout bivalva
pedicellariae
are situated
in
pedicellarial
pits
of
adzanbulacral
ossicles
(Plate 3,
Numbers l-5) or in pedicellarial
cups (Plate 8, Number 18) in
&in on the dorsal surface.
-
10
-
Other Elements
lhe
madreporite
(Plate 7,
Number 11)
is
a delicate
muzshIwm-&aped ossicle with a pattern superficially
resenbling
on the dorsal
surface.
Subspherical
gzxnules
brain coral
(Plate 7, Number 12) are variable in shape, being subspherical
to
Encrusting
granules
(Plate 8, Number 19) are
subeliptical.
uniform in size and daw-&aped
with an extended flat base.
5.2
Micxwztru=ture
'Ihe microstructure
of A. planci is an open system in which
the poxuxitymay
be as high-~~Btthurst,
1975). Within any
one elgnent, however, the mesh thickness,
pore size, and hate,
varies considerably
from the repesentative
exanples
PJ-itY,
&oun in Plates 9-11.
In the majority
of elements, the micmstruzture
is very
similar with fine calcite arrangd in a subromded to pentagonal
pattern
forming large pores.
Pedicellariae
retain
this predaninantly
pentagonal structure but the presence of a series of
terminating
in blmt peaks (Plate 11, Number 4), gives
ridges,
the pedicles
an overall
elongate appearance.
Abactinal
and
actinal spines do not generally have the pentagonal form. Their
fabric is elongate, parallel
to the lorg axis of the element
(Plate 11, Number 1).
5.3
Uxnistry
Electron
micropobe
A. planci to be canpxed
ii.6 mole percent MgC03.
analysis
reveals
the skeleton
of
of high magnesium calcite
with 8.2 -
-
6.
11
-
IWCOGNITIQNOFA.PLANCIINTEESEDI~AI~I~!~XXD
F'rankel
(1974, 1978) identified
hole
and fragmented
skeletal
debris in the "very poorly sorted and unconsolidated
(reefal)
sediment"thatheexanined.
According to Frankel (1978)
the parts most often preserved are spines, pedicels and ambulacral ossicles.
The preservation
of elements in the sedimentary
record will
largely
depend on their original
size, shape and
abmdance and the hydrodynamic
conditions
at the time of
deposition.
If cmun-ofthorns
starfish
are present in hundreds of
thousands during an outbreak on a single reef, as suggested by
3Zndea.n(1932), enormous potential
exists for the deposition
and
incorporation
into sediment of millions
of skeletal
elements.
This is pEtrticularly
so for ambulacrals,
adambulacrals,
actinal
secondary abactinals,
and spines, each of which
intermediates,
nunbers several hundred per animal.
The hydrodynamic conditions
prevelant when each animal dies
and disintegrates
is clearly a major determinant in the type of
element incorporated into the sediment and their state of preservation.
Snail, fragile
pedicellariae,
encrusting granules, and
subspherical
granules uould be especially
susceptible
to transand physical breakdown by the action of waves
port, dispersion,
and currents.
The elements most likely to survive turbid conditions and be
preserved more or less intact are those which are ccmpzt and
relatively
robust.
Based on this criterion,
adambulacrals,
actinal
intermediates
and the less conmon interbrachial
ossicles
should be present in any A. planci-rich
zone in uhich ossicles
are pesent.
Spines, and ornately-anulptured
ambulacrals,
abactinals,
and some secondary abactinals,
wuld
to physical disintegration.
orals, primary
be susceptible
"Jhe praninence of pedicles and spines in Frankel's samples
may be dtle to their sizn and shape &ich alloued then to fall
into cracks and crevices,
thereby avoiding perturbation.
Despite the ptential
for the preservation
of some elements,
the recognition
of large nunbers of crwn-ofthorns
parts in
sediment will necessarily
lead to the identification
of elements
via a detailed study of the micr.ostru:ture.
The recognition
of &ole or fragmentary elements in sedimat
is assisted by the distinct
mauve colouration
of A. planci pwts.
&ly the madreporite,
pedicellariae,
and pedicelrarial
cups lack
this pigmentation.
Intensity
of pigmentation varies betueen ossicle series and
within some series.
Those in which the colour is most pronomced
are the ossicles situated close to the surface of the animal i.e.
the primary and secondary abactinals,
actinal
intermediates,
Adanbulacrals
and ambulacrals are cow
margirds,
and spines.
siderably lighter in colour although still
with a distinct
purple
tinge.
First adanbulacrals,
orals and the interbrachial
ossicles
are a very pale mauve. Actinal spines display a large range of
colours frcm pestle mawe to darkmauve.
-
12
-
!Ihe ossicles of other stars examined by the author and all
studied by F'rankel (1974, 1977, 1978) are
other "stelleroids'
vjhite or cream. Blake (1979) reported that the ossicles of some
specimens of Echinastek modest& Pervier
are pale purple in
colour whilst the Creasteridae have white ossicles.
Skeletal elements of four stars conmo11on the Great l&wrier
Beef were conpared to those of A_. planci.
Species considered
uere three starfish
(Echinaster
luzonicus
(Gray), Euretaster
insignis
(Sladen), Linkia laevigata
(L.)) and one brittle
star
(Ophiocm
sp.).
Elements uhich ressnble ossicles in A. planci
were studied.
'Ihose with no physical
similarity
i?ere not
considered.
Some elements, particularly
ambulacral and dennal ossicles,
superficially
resenble their couHzerplrts
in A. planci
(Plate
12). Major moqhological
differences
exist,
howver, especially
in ossicle
size and the sculpturing
of articulation
surfaces.
Possible confusion is avoided by the snaller size and brilliant
white colouration
of ossicles
exaninecl fran each of the four
species.
According to h4xuell (1971), most asteroids can he differentiated
fr-cm Acanthaster by their
"dense, moderately porous
ekeletal
material";
it is the Qhiuroids
tiich
most closely
resonhle Acanthaster.
Mzxell
consider-d
that fragmented partions of Acanthaster
&eleton
can only be distinguished
fran
Ophiuroids if ccarser meshwrk fragments are present.
lhese conclusions are not readily apparent in Plate 13. The
ossicle microstructure
of SOme other sea stars does appear to be
similar to that of A. planci.
In the species exsnined, this uas
pwticularly
the c&e with the oral ossicle
of E. insignis
(Plate 13, Number 6). In general, houever, the micro&xcture
of
the elements of other asteroids
is denser and less porous, as
suggested byhhxwll.
-
7.
13
-
CXXLXJSION
An atlas of the skeletal
conponents of the,crov,n-ofthorns
starfish
(A. planci) is an essential tool if whole or fragmentary
elements are to be identified
in the sedimentary record.
The
gross morphology, microstrwture
and colour of croun-of-thorns
elements is sufficiently
different
from corresmnding
elements of
most other conmon reef-inhabiting
stars to avoid serious confusion.
With this atlas as an aid, future studies on reefal
debris may be able to determine the extent of croun-oftbwns
outbreaks in the pELst.
This project
Reef &wine Brk
provided courtesy
uas funded by a grant fram the Great Barrier
Authority.
Transport to John Rrewzr Reef wits
of Ibq Ewza's 'Reef Link'.
-
8.
14
-
-
BARNES, J. 8~ ENDEAN, R., 1964.
A dangerous starfish
Acanthaster planci (Linne).
Medical Journal of Australia,
1, 582-593.
BATHURST, R.G.C.,
1975.
Diagenesis, Elsevier
BLAKE,
D.B.,
ofthorns
Historv.
Carbonate
: New York.
1979. The affinities
sea star Acanthaster
13. 303-314.
Sediments
and Their
and origins of the mownGervais, Journal of Natural
BROWN, T.H. & WILLEY, K., 1972. Crown of Thorns.
The Death of
theGreat Barrier Reef?, Angus and IWertmn
: Sydney.
CASO, M.E., 1961.
Fstudios sobre asteridos
de Mexico.
&servaciones
mbre especies
pacificas
de1 genera
Acanthaster
y descripicion
de una subespecie neuva
Acanthaster elisii
pseudoplanci,
Anales de1 Instituto
de
Biologia
Universidad
National
Autonoma de Mexico, 32,
313-331.
, M.E., 1970. Moqhologia
externa de Acanthaster planci
Anales de1 Instituto
de Biologia Universidad
(Linnaeus),
National Autonoma de Mexico, Serie Ciencias de1 Mar y
Limnologia,
41, 63-78.
CHESHER, R.H.,
1275.
1970.
DANA, T.F., 1970.
169, 894.
Acanthaster:
Acanthaster:
A disaster?,
A rarity
Science,
in the past?,
167,
Science,
INlEAN, R., 1973. Pbpilation
explosions of Acanthaster planci
and associated destruction
of hematypic
corals in the
Indo-West acific
region.
in Jones, O.A. and l%dean, R.
(Eds) . Biology and Geolocof
Vol. II,
Coral Reefs.
Biology I. Acadmic Press : New York, 389438.
ENDEAN, R., 1977. Acanthaster planci infestations
the Great Barrier %ef.
Third International
Symposium,Miami,
1, 185-191.
ENDEAN, R., 1982. Australia's
Great Barrier
Queensland Press: St. Lucia.
FISCHER, J.L., 1969.
165, 645.
=L,
Starfish
infestation
of reefs of
Coral Reef
Reef, University
hypothesis,
of
Science,
E., 1975. Acanthaster in the past: Evidence from the
Great Barrier
&ef,
Crowwof-thorns
Starfish
Seminar
Proceedings, Brisbane, AGFS : Canberra, 159-165.
- 15 -
l!WNKEL, E., 1977. Previous Acanthaster aggregations
Great Barrier
F&ef, Third International
Coral
Symposium, 1, 201-208.
in the
Reef
I;RANKEL, E., 1978. Evidence frcxn the Great Barrier
Beef of
ancient Acanthaster aggregations,
Atoll Research Bulletin,
220, 75-93.
GREATBARRIER REEF MARINE PARK AUTHORITY, 1984. Reef User Report
Survey, Unpublished report of the Great Barrier Reef Marine
Park Authority,
Tomsville.
MAnSEN, E.J., 1955. A note on the sea star genus Acanthaster.
Videnskabelige
Meddelelser
fra Dansk Naturhistorisk
Forening, 117, 179-192.
MAXWELL, W.G.H., 1971. Echinoderm debris from Great Barrier Reef
sediment - distribution
and age. in kleh,
R.J., Harris,
C.L., Hnvey, J.M., hhxwell,
W.G.H., lhmsm,
J.M. and
Tranter, D.J. Report of the Comittee
on the Problem of the
Crown-ofthorns
Starfish
(Acanthaster
planci).
CSIRO :
Melbourne, 43-45.
MOORE, R.J., 1978.
Is Acanthaster
Nature. 271. 56-57.
planci
an r-strategist?,
MORAN, P., 1964.
Synopsis of Research on the Acanthaster
Phenomenon, AlMS : Tounsville.
Unpublished.
NlNMAN, W.A., 1970.
1274-1275.
Acanthaster:
A disaster?,
Science,
167,
NE%VMAN,W.A. 8~ DANA, T.F., 1974. Acanthaster: Tests of the time
course of coral destruction,
Science, 183, 103.
PEARSON, R.G., 1975. Coral reefs, unwedictable
and Acanthaster.
Crowwofthorns
Starfish
ings, Brisbane, AGIS : Canberra, 131-134.
climatic
factors
Seminar Proceed-
RANDALL, J.E., 1972. Chenical pollution
in the sea and the
cxw,n-of-thorns
starfish
(Acanthaster planci),
Biotropica,
4, 132-144.
SmCER, W.K. & WRIGHT, C.W., 1966. Asteromans.
in kbore, R.C.
(Ed.).
Treatise
on Invertebrate
PalaeontolG,
Part V,
Echinodermata 3, Vol. 1, Geological
Sxiety
of America :
University
of Kansas, U4-iT107.
VINE, P.J., 1973. Cram of'tborns
The natural
courses theory,
166, l-10.
(Acanthaster planci) plages:
Atoll
Research Bulletin,
Plates
-
17
-
ANAl’OMfoFA.PLANCI
la
Lateral view of mid-arm.
2 Admnbulacral ossicles.
1 Ambulacral
ossicles;
lb
Crosssectional
2 Adzmbulacral
2
lateral
view of mid-arm.
intermediate
ossicles.
3
lateral
view of proximal end of arm. 1 Interbrachial
plates; 2 Interbrachial
ossicle;
3 Oral ossicle; 4 Actinal
intermediate
spine; 5 Oral ossicle spine.
4
Lateral view of proximal
ossicle; 2 Oral ossicle;
5
1 Abactinal spine; 2 Micellarial
cup;
Dorsal skinofann.
3 Subspherical granule; 4 Encrusting granule on primary
abactinal ossicle.
6
Meshwork of dexnal ossicles.
1 Subspherical granule;
2 Fedicellaria
and pedicellarial
cup; 3 Secondary abactinal
ossicle; 4 Madreporite;
5 Unbarbed abactinal spine;
6 Primary abactinal ossicle.
7
1 Madreporite;
Dorsal skin of disc.
3 Primary abactinal ossicle.
view of mid-arm.
1 Ambulacral ossicles;
ossicles;
3 Adanbulacral furrow.
1 Actinal
spine;
2 Actinal
end of arm. 1First
ambulacral
3 Arch for interbrachial
ossicle.
2 Subspherical
granule;
-
18
-
Plate 1
-
1
2
19
-
Cross sectional view of arm's abactinal ossicles.
1 Abactinal spine; 2 primary abactinal ossicles;
abactinal ossicles.
Actinal view of dermal ossicles.
2 Secondary abactinal oesicles;
3 Secondary
1 Subspherical granules;
3 primary abactinal oesicle.
3 Oral ossicle; 4 Ambulacral ossicle;
5 First ambulacral
ossicle; 6 Adambulacral ossicle;
7 Secondary abactinal
ossicle; 8 Secondary abactinal ossicle;
9 Interbrachial
ossicle; 10 Actinal intermediate
ossicle;
11 primary
abactinal ossicle;
12 Interbrachial
plate.
a.
b.
c.
d.
e.
f.
g*
h.
1.
;I:
1.
m.
n.
0.
P*
q*
r.
s.
t.
u.
V.
w.
Oral - first ambulacral articulation
surface
First ambulacral ossicle articulation
bEtr
Oral - first adambulacral seat
Actinal spine bases
proximal tip
Ambulacralanbulacral articulation
surface
Adradial portion of ambulacral ossicle
Wings for ambulacral - adambulacral muscles
First ambulacral ridge
Ambulacral - anbulacral articulation
surfaces
Distal abactinal extension
Pedicellarial
valve
Secondary abactinal - @nary/secondary
abactinal articulation
surfaces
Body
Neck
Interbrachial
ossicle - interbrachial
plate articulation
surface
Stub
Actinal intermediate - actinal spine articulation
surface
Muscle/&in
attachemat
scar
Actinal intermediate - actinal intermediate
articulation
surface
primary abactinal - abactinal spine articulation
surface
primary abactinal - secondary abactinal articulation
surfaces
Interbrachial
plate - interbrachial
plate articulation
surface
,
-
20
Plate 2
a
h
P
4
- 21
-
PLmE 3
A. lJI.ANcI
-lzLJmNT-
15 Admbulacral
ossicles la x 18.8; lb - 5d x 8
Actinal surface towxrdstop
of page
1 Distal (arm-tip)
ossicle lateral view
2-5 Mid- to proximal am ossicles
2Sa = furrow view; 5b= distal view; 5c= lateral
5d= proximal view
view;
6-g Ambulacral ossicles 6a-c, 7, 8a, 9a x 6.8; 8b, 9b x 14.6.
6a= furrow view; 6b= lateral view; 6c= proximal view;
7-9 = furrowvie~
- 22 -
Plate
5b
8b
1
%
9a
9b
-
23
-
PLlA!rE4
A.PLlANCI-ZLEMNTm
Oral (mcmtkangle)
ossicle x 4.6
Actinal. surface touardstopof
page
la= furrow view; lb= lateral view
First ambulacral ossicle x 4.6
2a= lateral view; 2b = furrow view
Interbrachial
3a= lateral
ossicle x 4.6
view; 3b= &lique
4-9
Actinal intemsdiate
ossicles
See also E'late5Number7
10
Mwginal
ossicle
x 7.5
lateral
x 7.5
view
-__
-
24
-
,Plate 4
46
- 25
-
A. PLANCI -J3LEmNTl-6
Interbrachial
plates
7-10 Secondary abactinal
x 7.5
osxicles
x 7.5
-
26
-
Plate
5
- 27
-
A.PLANCI-m,mrwrKRPHMGY
l-11 Secondary abactinal
ossicles
x 7.5
-
28
-
Plate 6
lb
6a
/
“‘_
:
7a
8a
-
29
-
PUWE 7
1*,
8-10
Primary abactinal ossicles
1, 2 x7.5; 3 x4.6; 4 x4; 5-6, 8-10 x7.5
5 and 9 are arm-tip ossicles,
others are mid-arm
to body ossicles.
7
Actinal imtermdiate
ossicle x 7.5
See al= Plate4 Numkrs 4-9
11
Madreporite xl3
lla = lateral view;
llc = actinal view
12
Subspherical
lib=
granule x 75
abactinal
view;
- 30
-
Plate
7
-
-
31
PLBTE 8
A. PLANCI -EzEMm!-
1,
4-8
Actinal spines
1, 4 x7.5; 5 x4.5; W3 x7.5
1, 4 fran admbulacral
actinal intermediate
distal end of oxal ossicle,
5 frcm proximal
of oral ossicle,
&8 frcm furrow mw of
admbulacral
and oral ossicles.
2-3
EB.rbed abactinal
spines
9-17
Pedicellariae
x 18
9-12, 14-17, individml
ventral surfaces
13 paired valves
valves,
18
Micellarial
cup x18
19
Encrusting
granules x 146
dorsal
and
and
end
-
32
-
Plate 8
lb
2b
6
” .,
P
19b
19c
- 33
-
PLATE9
A. PLAUCI -HI-OFAdanbulacral
Ambulacral
Actinal
ossicle
ossicle
intermediate
ossicle
Secondary abactinal ossicle
a= x300
b= x600
-
34
-
Plate 9
-
35
-
PLAm 10
Oral (mouth-angle)
Interbrachial
ossicle
ossicle
Wdreporite
Interbrachial
plate
a=~300
b=x600
- 36
-
Plate 10
- 37
-
PLATE11
1
Abactinal
2
Actinal
3
Primary abactinal
4
Rdicellariae
a=~300
b=x600
spine
spine
ossicle
-
38
Plate 11
-
Linkia
1
2
3
39
-
laevigata
Ambulacral ossicle x 15
Dmmal ossicle x 30
Adambulacral ossicle x 22.5
Echinaster luzonicus
4
Oral ossicle x 23.5
Actinal surface to top of page
Arnabulacral ossicle x 15
5
6
Admbulacral
ossicle x 30
7-11
Dxmal ossicles x 22.5
12
Spinex30
Euretaster insignis
13
Ambulacral ossicle x 15
14
Oral ossicle x 22.5
Actinal surface to top of page
15
First ambulacml ossicle x 28.5
16-17 Ventral spines x 15
18
Spiney ossicle x 25.5
ophioccm sp.
Am spine x 15
19
- 40 -
Plate 12
6
10
^
-
- 41
1
-
PIA!l!E 13
Linkia
laevigata
- admbulacml
ossicle
x 300
Linkia
laevigata
- adambulacral
ossicle
x 300
Echinaster
luzonicus
- admbulacral
Echinaster
luzonicus
- spine x 300
Euretaster
insignis
- mbulacral
Euretaster
insimis
- oral ossicle
Euretaster
insignis
- spine x 300
Ophioccmasp.
- spinex300
ossicle
ossicle
x 300
x 300
x 300
- 42
-
Plate 13
__
-
--