Download Shallow-water comatulid crinoids (Echinodermata) from Barbados, West Indies

Shallow-water comatulid crinoids (Echinodermata)from Barbados, West Indies
Can. J. Zool. Downloaded from www.nrcresearchpress.com by Utah State University - Logan on 02/15/13
For personal use only.
Museum of Paleontology, University of Michigan, Ann Arbor, MI., U.S.A.48109
Received January 3, 1979
LIDDELL,
W. D. 1979. Shallow-water comatulid crinoids (Echinodermata) from Barbados, West
Indies. Can. J. Zool. 57: 2413-2420.
The shallow-water crinoid fauna of the northwest coast of Barbados consists of six species:
Analcidometra armata (Pourtales), Nemasterdiscoidea (P. H. Carpenter), Nemaster rubiginosa
(Pourtales), Comactinia echinoptera (J. Miiller), Ctenantedon kinziei Meyer, and Tropiometra
carinata (Lamarck). Of these, only the first three may be regarded as common. The highest
concentrations of crinoids occur along the seaward slope of the bank reef, which parallels the
coast. Here the combined densities of crinoids over large areas may reach 1. 15/m2, which is
comparable with or higher than densities found elsewhere in the Caribbean. The co-occurring
Nemaster discoidea and Nemaster rubiginosa exhibit broadly overlapping bathymetric ranges
and habitat utilization patterns. Of the more common species, Analcidometra armata alone
shows a restricted bathymetric distribution and a unique substrate type (an exposed position on
the gorgonian Pseudopterogorgia sp.).
LIDDELL,W. D. 1979. Shallow-water comatulid crinoids (Echinodermata) from Barbados, West
Indies. Can. J. Zool. 57: 2413-2420.
Lafaune crinoide deq eaux peu profondes de la cdte nord-ouest de la Barbade se compose de six
espkces: Annlcidomerrd nrm~rfu[Pourtalks). Nem~lstrrdiscoidea (P,H. Carpenter). Nemasrrr
rtrl)iginosr~(Puurlales), Cnmacrinifl erl~inoptera(1. Miiller). Ctenanr~d<+n
kinziei Meyer et
Trnpiometra curinura (Lamarck). Seules les trois premieres de ceq ~ s p e c e ssunt asscz communes. C'est sur la pente du ricif dirigiie vers Ce large et parallkle b la cbte qu'habire la plus grande
concentration de crinoides. A cet enilroit. la densite totate des crinoides sur de grandes surfaces
peuL atteindre 1.15/m2, valeur comparable ou ~tipirieureaux densites m e s u r h en d'autres
points des Caraibes. Nernnster di.\ cnirlen el Nemnsrer rrrhiginasa. esp+ces qui cohabiten1
occupent des zone5 bathyrnitriques qui se rccoupent largernent et unt d e habitats
~
semhlables.
Drs especes communes. seule AnrrlriJnntetru nrnrnta a une repart~tionbathymktrique restreinte
et un type de substrat particulier [position exposee sur la gorgone Ps~rrdoprerc>gorgin
sp.).
[Traduit par le journal]
.
Introduction
Comatulid crinoids are conspicuous members of
many Caribbean reef communities. The general
zoogeographic and bathymetric distributions of
shallow-water crinoids within the Caribbean are
documented by Clark (1931, 1947, 1950), Macurda
and Meyer (19771, and Meyer et al. (1978). Recently, detailed studies of crinoid'distributions and
their ecology have been made possible through the
use of SCUBA diving and in situ observations. The
crinoid faunas of Jamaica and Curacao have been
described by Meyer (1973a, 1973b, respectively),
that of Colombia by Meyer and Macurda (1976),
and that of the Bahamas by Macurda (1973, 1975).
The present paper deals with the ecology and distributions of the shallow-water crinoids of the
northwest coast of Barbados, West Indies (13'15'
N , .59"3OfW).
Methods
The crinoid fauna was examined in the vicinity of the Bellairs
Research Institute of McGill University, St. James, Barbados
'Present address: Department of Earth Sciences, University
of New Orleans, Lake Front, New Orleans, LA, U.S.A. 70122.
during August, 1977. Observations were made by SCUBA diving at several sites, including nearshore beach rock in the
vicinity of Six Men's Bay to the north of Bellairs, the Bellairs
fringing reef, and the "bank reef' directly offshore of the Bellairs Institute, as well as a sitejust south of the Institute (Figs. l ,
2). Investigations were conducted to depths of 36m, which
represents the approximate lower limit of reef growth in the
study area. Crinoids were counted within 2-m wide strips
positioned parallel to depth contours. The location of each
crinoid was plotted within the transect strips and data on substrate (habitat) type, height of crinoid above reef floor, amount
of arm extension from substrate, and orientation of arms were
recorded. The latter was determined by measuring the compass
direction in which the crinoid's arm array was extended from its
habitat.
Results
The shallow-water crinoid fauna of Barbados
consists of six species: Analcidometra armata
(Pourtales), Comactinia echinoptera (J. Miiller),
Ctenantedon kinziei Meyer, Nemaster discoidea
(P. H . Carpenter), Nemaster rubiginosa (Pourtales), and Tropiometra carinata (Lamarck) (Table
1; Figs. 3, 4). Of these, only three, Nemaster discoidea, N . rubiginosa, and Analcidometra armata,
may be regarded as common and will be examined
0008-4301/79/122413-08$01.W/O
@ 1979 National Research Council of Canada/Conseil national de recherches du Canada
2414
CAN. J. ZOOL. VOL. 57. 1979
S i x M e n ' s Boy
Speightstown
Can. J. Zool. Downloaded from www.nrcresearchpress.com by Utah State University - Logan on 02/15/13
For personal use only.
Bellairs-
Bridgetown
2 4
BARBADOS
FIG. 1 . Map of Barbados showing study area.
1
FIG.2. Reef profile off the Bellairs Research Institute (Vertical scale exaggerated approximately three times).
in detail. With the exception of the closely related
N. discoidea and N. rubiginosa, the members of
the fauna are readily distinguished on the basis of
differences in morphology as well as behavior.
Despite many similarities, Nemaster discoidea
and N. rubiginosa are morphologically distinct.
One feature which is readily apparent in the field is
that the arms of N. discoidea are more slender
(1.4mm vs. 1.9mm mean diameters at base) and
often shorter (85 mm vs. 115 mm mean lengths)
than those of N. rubiginosa. Their skeletons also
differ in the position of the second syzygial articulations of the free arms (occurring approximately
between brachials 8 and 9 in N. discoidea and between brachials 11 and 12 in N. rubiginosa),
number of comb-bearing pinnules (two or three in
N. discoidea and three or four in N. rubiginosa),
and in length of arm rays (equality of all rays in the
former, shortening of C and D rays in the latter
(Clark 1931; Meyer 1973a)).
At Barbados, the arms of N. discoidea are often a
pale yellow-green with a thin black abambulacral
stripe and white "beaded" pinnules with black
tips. Forms of N. discoidea with entirely black
arms are less commonly encountered as well. It
should be noted that Clark's (1931, p. 215) key to
the species of Nemaster lists the presence of a
black abambulacral (dorsal) stripe as a characteristic of N. rubiginosa, not N. discoidea. This feature
of the key is in need of revision as the description
probably pertains to specimens of N. discoidea
more common elsewhere in the Caribbean possessing black arms, which could not be expected to
show a black abambulacral stripe. Furthermore,
upon close examination, arms of such black forms
of N. discoidea frequently show a thin black abambulacral stripe in the lighter colored, most proximal
regions. The specimens of N. discoidea from Barbados agree with Clark's description in most other
respects.
Nemaster rubiginosa possesses arms that are
orange to brown or black with a black abambulacral
stripe and orange to brown pinnules (with or without orange or yellow tips). The population of N.
rubiginosa is dominated by large brown to black
forms that comprise approximately 75% of the
population. In addition to larger size these varieties
show an increase in arm number (average 24) and
are similar to Clark's (1931) N. iowensis (Springer),
later synonomized with N. rubiginosa by Meyer
(19736). As such, the population of N. rubiginosa
shows a close affinity to those of southern Caribbean sites such as Colombia and Curacao (Meyer
19736; Meyer and Macurda 1976; personal observations) and a lesser affinity to those of Jamaica
(Meyer 1973a), the Bahamas (Macurda 1975), and
the Cayman and Virgin Islands (D. B. Macurda, Jr.,
and D. L. Meyer, personal communication). In
contrast, the population of N. discoidea consists
largely of a variety that is widespread throughout
the Caribbean.
Fringing Reef and Nearshore Localities
Beach rock extending from the shore to a distance of approximately 50 m seaward and 5 m depth
was examined in the area of Six Men's Bay (Fig. 1).
No crinoids were observed although numerous
echinoids and other invertebrates were present on
or in the beach rock and Porites porites stands.
This is in contrast to the numerous specimens of
Tropiometra carinata present on the beach rock in
1974 (D. B. Macurda, Jr., and D. L. Meyer, personal communication). Tropiometra is also mentioned in a description of the site by James et al.
(1977). The absence of Tropiometra may be partially attributed to collecting; however, the effect of
environmental fluctuations in such a shallow and
nearshore setting must also be considered.
The Bellairs fringing reef and nearshore areas
(Figs. 1, 2) have been described by Lewis (1960),
James et al. (1977), and Steam et al. (1977). Back-
LIDDELL
2415
TABLE
1. Shallow-water crinoids of the northwest coast of Barbados and their identifying features
Can. J. Zool. Downloaded from www.nrcresearchpress.com by Utah State University - Logan on 02/15/13
For personal use only.
Order Comatulidaa
Family Antedonidae
Ctenantedon kinziei Meyer
Ten arms, length 10 cm, slender, white to pale green; pinnules long and slender and arranged in two rows; cirri relatively
long (17 mm); cryptic or nocturnal, capable of swimming.
Family Comasteridae
Comactinia echinoptera ( J . Miiller)
Ten arms, length 10-18 cm, stout proximally, arms and pinnules red (may have a mottled or spotted appearance); pinnules
arranged in two planar rows; nocturnal.
Nemaster discoidea ( P . H . Carpenter)
Twenty arms, length 7-15 cm (mean 8.5 cm), more slender than N . rubiginosa (1.4 mm vs. 1.8 mm mean diameter at base),
yellow-green with black abambulacral stripe, occasionally black; pinnules beaded, white with black tips, arranged in
four rows (tetrad arrangement); continuously exposed.
Nenzaster rubiginosa (Pourtal&s)
Twenty to 30 or more arms (mean 24), length 10-20 cm (mean 11.5 cm); arms and pinnules orange or brown to black with
black abambulacral stripe; pinnules may possess orange or yellow tips, arranged in four rows (tetrad arrangement);
continuously exposed.
Family Colobometridae
Analcidometra armata (Pourtales)
Ten arms, approximately 4-5 cm in length, grey-green with red bands; short pinnules arranged in two planar rows; inhabits
gorgonians, capable of swimming.
Family Tropiometridae
Tropiometra carinata carinata (Lamarck)
Ten arms, length 10-15 cm, brown with yellow bands; pinnules arranged in two planar rows; continuously exposed.
.See Clark (1931) for familial characteristics.
reef areas (swash zone) consist of sand bottoms
with dead coral. The fringing reef has been divided
into several bathymetric-ecological zones by
Stearn et al. (1977) that extend seaward from the
reef crest at a low slope. Crinoids appear to be
absent from the back-reef areas as well as the flat
terrace of the fringing reef.
At approximately 300 m from the beach, the reef
terrace gives way to the seaward slope of the fringing reef, which begins at a depth of approximately
10m and continues to 20 or 30m at a slope of
approximately 45". This slope supports a wide variety of scleractinians and sponges. Nemaster discoidea, N . rubiginosa, and Tropiometra carinata
were observed on this slope although in very low
concentrations (<0. l/m2).
Bank Reef
The bank reef off Bellairs, a Holocene mantle on
a drowned Pleistocene barrier reef (Macintyre
1967), is separated from the fringing reef by a sandy
trench reaching 20-30 m in depth (Fig. 2). A general
description of the structure and associated fauna is
provided by Ott (1975). The bank reef rises at approximately 25" from 20 m on its landward side to a
nearly level platform at about 13 m. This platform
may be up to 100 m wide and descends at a slope of
approximately 30" on its seaward side to about
36 m, where a more gently sloping sand plain be-
gins. Coral density (as determined by line transects) is high on the seaward slope of the bank reef,
reaching 70% coverage by live and dead coral.
Coverage by live or dead coral on the level platform
of the bank reef is somewhat less (54%). The
greatest numbers of crinoids were encountered on
the seaward slope of the bank reef. The landward
slope of the bank reef supports lesser numbers of
crinoids and the platform still fewer.
Crinoids present on the bank reef include
Nemaster discoidea, N . rubiginosa, and Analcidometra armata. In addition, four specimens of
the rare and normally cryptic (Meyer 1972)
Ctenantedon kinziei were also observed with their
arms extending from coral substrates (two diurnally and two nocturnally). Analcidometra, which
lives almost exclusively on the gorgonian Pseudopterogorgia sp., is found on the platform as well as
the seaward slope of the bank reef, where its distribution is apparently linked to the profusion of
gorgonians on the platform and upper slope. The
distribution of Analcidometra is patchy with certain specimens of Pseudopterogorgia containing
no or only 1 or 2 individuals of Analcidornetra,
whereas others may contain as many as 20. The
most abundant crinoids are the two Nemaster
species, of which N . discoidea predominates at
most depths (Table 2, Fig. 5). Combined densities
of N. discoidea and N . rubiginosa over large areas
CAN. J. ZOOL. VOL. 57. 1979
Can. J. Zool. Downloaded from www.nrcresearchpress.com by Utah State University - Logan on 02/15/13
For personal use only.
2416
FIG.3. Barbados crinoid fauna. (A) Analcidometra armara (Pourtalts) on Pseudopterogorgia sp. x 3. (B) Ctenantedon
kinziei Meyer, artificially exposed. x 0.75. (C) Comactinia echinoptera ( J . Miiller) at night; note concealment of disk. ~ 0 . 5 .
(D) Tropiometra c,arinata (Lamarck). x 0.25. (E) Comactinia echinoprera, detail of pinnule arrangement and tube feet; note
planar pinnule array. x 4. (F)Nemaster discoidea ( P . H . Carpenter), detail of pinnule arrangement and tube feet; note tetrad
pinnule arrangement and beaded nature of pinnules. x 4.
Can. J. Zool. Downloaded from www.nrcresearchpress.com by Utah State University - Logan on 02/15/13
For personal use only.
FIG.4. Crinoid habitats. (A) Nemaster rubiginosa (Pourtales) in vertical crevice between heads of Montastrea cauernosa,
M. annularis, and Siderastrea siderea. ~ 0 . 5(B)
. Nemaster rubiginosa under Colpophyllia sp. plate. x0.25. (C) Nemaster
rubiginosa, detail of arm of brown form with yellow-tipped pinnules; note tetrad pinnule arrangement. x 0.75. (D) Nemaster
rubiginosa with arms well extended from habitat at night. x 0.3. (E) Nemasterdiscoidea (P. H . Carpenter)under Agaricia sp.
plate. x 0.8. (F) Nemaster discoidea, disk exposed at night. x 4.
2418
CAN. J . ZOOL. VOL. 5 7 , 1979
Can. J. Zool. Downloaded from www.nrcresearchpress.com by Utah State University - Logan on 02/15/13
For personal use only.
TABLE2. Distributions of Nemaster species with depth
perhaps, Ctenantedon kinziei). Within the first
group, Tropiometra (Fig. 3D) was too uncommon
N. discoidea
N. rubiginosa
to draw conclusions about its habitat requirements
at Barbados. At other Caribbean sites where
Depth,
Area,
Density,
Density,
Tropiometra co-occurs with N. discoidea and N.
m
m2
N
m-2
N
m-z
rubiginosa it appears to inhabit depth ranges and
15
100
1
0.01
5
0.05
substrate types similar to those of the Nemaster
18
47
9
0.19
2
0.04
species with the exception that, unlike the others, it
21-24
80
78
0.98
13
0.16
may also extend into very shallow water (personal
27
20
21
1.05
2
0.10
observation).
1
0.05
30
20
13
0.65
Total
267
Analcidometra armata (Fig. 3A), as discussed
earlier, chiefly inhabits the gorgonian Pseudoon the seaward slope of the bank reef are greatest pterogorgia sp., resulting in an elevation above the
below 20 m and may reach 1. 15/m2, which is ap- sea bottom of 10 to 150cm or more. In addition to
proximately as high or higher than observed inhabiting a rather narrow depth range (approxielsewhere in the Caribbean. Maximum numbers of mately 13.5- 18 m), this small, 10-armed crinoid is
crinoids censused by the author over large areas at clearly utilizing a restricted substrate niche, reJamaica were 1.22/m2 and at Curacao were moved from that of the other shallow-water com0.23/m2. Me yet (1973a, 19736) found similar com- atulids, and convergent with that of some
ophiuroids (e.g. certain Ophiothrix species).
bined crinoid densities at Jamaica and Curacao.
Nemaster discoidea and N. rubiginosa were also
The morphologically similar species of N. disabundant on .the seaward slope of the bank reef coidea and N. rubiginosa (Figs. 3F, 4) show
approximately 1km south of the Bellairs Institute. broadly overlapping bathymetric distributions
Crinoid densities at this site exceeded those of the (Fig. 5, Table 2). In addition, these congeneric
bank reef immediately off Bellairs in the shallower, species appear to overlap considerably in mi15-20 m, depth range where N. discoidea reached crohabitat utilization (Fig. 6). The principal conaverage densities of 0.58/m2 and N. rubiginosa straints on habitat selection appear to be the re0.40/m2 for a combined density of 0.98/m2 over quirements that the fleshy disk of the crinoid be
approximately 100 m2. The increase may be due, in concealed and the crinoid elevated into the water
part, to greater coral cover and thus more abundant column for feeding purposes. The former is most
crinoid habitats at this site. Also, this locality may likely a response to avoid predation by diurnal presuffer less disturbance from researchers and col- dators as nocturnal observations indicate that
lectors as a result of lessened proximity to the Bel- many individuals of both N. discoidea and N.
rubiginosa may further extend their arms or even
lairs Institute.
perch upon the outsides of coral heads and expose
Crinoid Microhabitats and Behavior
their disks while feeding at night (Figs. 4D, 4F).
The crinoids present may be divided into two
The four most common substrate morphologies
groups: (1) those with arms continuously extended
utilized by both N. discoidea and N. rubiginosa are
(Nemaster discoidea, N. rubiginosa, Tropiometra
vertical crevices between heads of massive
carinata, and Analcidornetra arrnata) and (2) noc- (1)
dome corals such as Siderastrea siderea, Monturnal forms (Cornactinia echinoptera and, tastrea cavernosa, M. annularis, and others (Fig.
4A); (2) the curled lower edge of dome corals such
D e p t h rn
as M. cavernosa and M. annularis; (3) the under15
sides of coral plates, largely Porites astreoides and
18
M.
annularis (Figs. 4B, 4E); and (4) overhangs
21
formed by eroded coral rock (Fig. 6). Microhabitat
24
selection appears to be largely random with the
27
most common coral substrates (as determined by
30
33
line transects) being selected most frequently, al36
though certain substrate morphologies such as
overhanging
edges of M. cavernosa domes are obFIG.5. Bathymetric distributions of Nemaster discoidea and
Nemaster rubiginosa in transect area on seaward slope of bank
viously preferable to the open framework of corals
reef immediately off the Bellairs Research Institute. Horizontal
such as Acropora cervicornis. No significant differlines at 14 and 36m indicate approximate upper and lower limits
ences ( P < 0.05) exist between substrate utilization
of bank reef. Dashed boundaries below 30m indicate inferred
patterns
of the two species (based on contingency
crinoid distributions as bank reef in transect area was divided
into coral fingers at this depth that were not transected.
tables and the x2 statistic).
LIDDELL
the water column than does N. discoidea (13.5 cm
versus 8.0cm by day). Proportionately, however,
the two crinoids extend nearly the same amounts of
CORRL KNOBS
their arm arrays (approximately 65%). Also, there
LO
VERT. CREVICE
w
is some indication that at a given depth N.
e
CORRL FINGERS
rubiginosa may occupy a somewhat higher position
CORRL PLATES
on coral substrates than N. discoidea does, alCI:
though sample sizes for any one depth are small.
CORAL DOME EOGE t
m
The average height for both species is 10-15 cm.
ROOF
u
1
Members of the second behavioral group of
n1sc.
crinoids (cryptic or nocturnal species) occur but
appear to be rare at Barbados. A few specimens of
N.O.
N.R.
Comactinia echinoptera (Figs. 3C, 3E) have been
FIG.6. Substrate utilization patterns for N . discoidea (N.D.)
reported from the area of Maycock's Bay, located
and N. rubiginosa (N.R.) between 15 and 23 m on the seaward
slope of the bank reef immediately off the Bellairs Research to the North of the Bellairs Institute (Fig. 1) (D. B.
Macurda, Jr., and D. L. Meyer, personal comInstitute. Vert., vertical; Misc., miscellaneous.
munication), but it is apparently not present or else
For those crinoids living along the outer slope of is very rare on the reef off Bellairs. At Jamaica
the bank reef, there is a tendency to position the Comactinia overlaps in depth with Nemaster disbody such that the long axes of the arm arrays are coidea and N. rubiginosa on the forereef and ocoriented outward (seaward) from the reef slope cupies much the same general habitats as the
(Fig. 7). Of the specimens measured, 70% were Nemaster species. Comactinia, however, appears
oriented parallel to or outward from the reef slope. to prefer sites adjacent to narrow tunnels or
This orientation probably allows the crinoids to crevices in the coral into which it retreats during the
take advantage of currents flowing along the reef day.
slope for feeding.
Ctenantedon kinziei (Fig. 3B) has been characBecause of its larger overall size N. rubiginosa terized as highly cryptic by Meyer (1972). At Barextends, on the average, a greater length of arm into bados a total of only four specimens was observed
with their arms extending from coral substrates on
the seaward slope of the bank reef. It is probable
that overall numbers are much higher but most
specimens remain hidden and extend their arms
and feed solely within caverns in the coral
framework.
Discussion
At Barbados, as well as elsewhere throughout
the Caribbean, crinoids (with the exception of
Tropiometra) rarely occur in depths of less than
8-10 m. The enrichment of crinoids on the seaward
slope of the bank reef relative to both the landward
slope of the bank reef and the seaward slope of the
Bellairs fringing reef may be due to increased water
movement at the former site, resulting in more favorable conditions for suspension feeding by the
crinoids. Meyer (1973a) cites a similar increase in
crinoid numbers at prominent slope breaks at
Jamaica and attributes this to increased water
movement at these sites. The increase in abundance of crinoids with depth on the bank reef (Fig.
5) may reflect increasing abundance of suitable
crinoid habitat types with depth. At Jamaica and
Curacao, however, transects have similarly shown
optimal ranges for crinoids (based upon highest
FIG.7. Orientation of arm arrays of Nemaster discoidea and densities) to occur between 20 and 25m despite
comparable coral coverage at both lesser and
Nemaster rubiginosa relative to habitats on outer slope of bank
reef (for 3 1 individuals). Trend or strike of reef slope is 150-330". greater depths at these sites.
CRINOID HABITATS
40
30
20
10
PERCENT
0
10
20
30
'40
t
Can. J. Zool. Downloaded from www.nrcresearchpress.com by Utah State University - Logan on 02/15/13
For personal use only.
2419
Can. J. Zool. Downloaded from www.nrcresearchpress.com by Utah State University - Logan on 02/15/13
For personal use only.
2420
CAN. J . ZOOL.
In addition to exhibiting considerable overlap in
bathymetry and habitat utilization, N. rubiginosa
and N. discoidea also show great similarity in food
materials captured, based on preliminary studies.
Such overlap in resource use by the congeneric
Nemaster species, although in seeming contradiction with niche theory, may be due to reduced
competition as a result of low crinoid densities.
Predation is one means by which numbers may be
so reduced. Predator control of community structure has been described by Hairston et al. (1960),
Slobodkin (1964), Paine (1966), and others. Although direct predation by fish upon crinoids has
not been well documented (Clark (1921) states that
fish appeared not to feed upon crinoids), there is a
growing body of evidence (cited in Meyer and
Macurda 1977) suggesting that fish predation upon
crinoids may indeed take place. The partially concealed posture of some crinoids by day
(Tropiometra carinata, N. rubiginosa, and N. discoidea) and wholly nocturnal or cryptic life mode of
others (Comactinia echinoptera and Ctenantedon
kinziei) suggests a response to predators.
Acknowledgements
I wish to extend my appreciation to D. B.
Macurda, Jr., and D. L. Meyer, who have provided
suggestions concerning this manuscript, and to
S. L. Ohlhorst for assistance in various stages of
the study. I also thank the staff of the Bellairs Research Institute of McGill University, St. James,
Barbados, for use of the facilities. This study was
financed by a University of Michigan (Rackham)
predoctoral research grant, a Scott Turner Awards
in Earth Science research grant (Department of
Geology and Mineralogy, University of Michigan),
and a Sigma Xi grant-in-aid of research.
CLARK,A. H. 1921. A monograph of the existing crinoids. U.S.
Natl. Mus. Bull. No. 82. Part 2. pp. 1-795.
1931. A monograph of the existing crinoids. U.S. Natl.
Mus. Bull. No. 82. Part 3. pp. 1-816.
1947. A monograph of the existing crinoids, U.S. Natl.
Mus. Bull. No. 82. Part 4b. pp. 1-473.
1950. A monograph of the existing crinoids, U.S. Natl.
Mus. Bull. No. 82. Part 4c. pp. 1-383.
N. G., F . E. SMITH,and L. B. SLOBODKIN.
1960.
HAIRSTON,
Community structure, population control and competition.
Am. Nat. 94: 421-425.
and R. S, HARRISON.
1977. Field
JAMES,N. P., C. W. STEARN,
guide book to modern and Pleistocene reef carbonates, Barbados, W.I. Third International Coral Reef Symposium,
Miami. pp. 1-30.
LEWIS,J . B. 1960. The coral reefs and coral communities of
Barbados, W.I. Can. J . Zool. 38: 1133-1 145.
MACINTYRE,
I. G. 1967. Submerged coral reefs, West Coast of
Barbados, West Indies. Can. J . Earth Sci. 4: 461-474.
D. B., JR. 1973. Ecology of comatulid crinoids at
MACURDA,
Grand Bahama Island. Hydro-lab J. 2: 9-24.
1975. The bathymetry and zoogeography of shallowwater crinoids in the Bahama Islands. Hydro-lab J . 3: 5-24.
MACURDA,
D. B., JR.,and D. L. MEYER.1977. Crinoidsof West
Indian coral reefs. Am. Assoc. Petrol. Geol. Stud. Geol. No.
4: 231-237.
MEYER,D. L. 1972. Ctenantedon, a new antedonid crinoid
convergent with comasterids. Bull. Mar. Sci. 22: 53-66.
1973a. Distributions and living habits of comatulid
crinoids near Discovery Bay, Jamaica. Bull. Mar. Sci. 23:
244-259.
19736. Feeding behavior and ecology of shallow-water
unstalked crinoids (Echinodermata) in the Caribbean Sea.
Mar. Biol. 22: 105-130.
MEYER,D. L., and D. B. MACURDA,
JR. 1976. Distribution of
shallow-water crinoids near Santa Marta, Colombia. Mitt.
Inst. Colombo-Aleman Invest. Cient. 8: 141-156.
1977. Adaptive radiation of the comatulid crinoids.
Paleobiology, 3: 74-82.
JR. 1978.
MEYER,D. L., C. G. MESSING,and D. B. MACURDA,
Zoogeography and bathymetric distribution of tropical weste m Atlantic Crinoidea (Echinodermata). Bull. Mar. Sci. 28:
412-441.
OTT, B. 1975. Community patterns on a submerged barrier reef
at Barbados, West Indies. Int. Rev. Gesamten Hydrobiol. 60:
719-736.
PAINE,R. T. 1966. Food web complexity and species diversity.
Am. Nat. 100: 65-75.
SLOBODKIN,
L. B. 1964. Ecological populations of Hydrida. J.
Anim. Ecol. 33(Suppl.): 131-148.
STEARN,C. W., T. P. SCOFFIN,and W. MARTINDALE.
1977.
Calcium carbonate budget of a fringing reef on the west coast
of Barbados. Part I. Zonation and productivity. Bull. Mar. Sci.
27: 479-510.