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Diet and feeding in the sea star Astropecten indicus (Döderlein, 1888)

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Diet and feeding in the sea star Astropecten indicus (Döderlein, 1888)

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This study investigates the feeding ecology of Astropecten indicus, one of the most common sea stars in Singapore's waters. Examination of the regurgitated stomach contents of 69 specimens collected from four sites revealed that A. indicus is a generalist molluscan feeder; but the Asian date mussel, Musculista senhousia, was the dominant prey species (42.68%). Astropecten indicus preferred M. senhousia over the button snail, Umbonium vestiarium, when given a choice under laboratory conditions. This pattern was signifi cant, and held for experiments regardless of whether prey were shelled or unshelled. Astropecten indicus also consumed more M. senhousia than U. vestiarium when fed these prey ad libitum. This is the fi rst study of its kind on A. indicus and thus contributes to the small pool of knowledge regarding the ecology of this species.
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251
THE RAFFLES BULLETIN OF ZOOLOGY 2011
DIET AND FEEDING IN THE SEA STAR ASTROPECTEN INDICUS (DÖDERLEIN, 1888)
K. S. Loh
Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore.
Email: kokshengz@gmail.com
Peter A. Todd
Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore.
Email: dbspat@nus.edu.sg (corresponding author)
ABSTRACT. This study investigates the feeding ecology of Astropecten indicus, one of the most common
sea stars in Singapore’s waters. Examination of the regurgitated stomach contents of 69 specimens collected
from four sites revealed that A. indicus is a generalist molluscan feeder; but the Asian date mussel, Musculista
senhousia, was the dominant prey species (42.68%). Astropecten indicus preferred M. senhousia over the
button snail, Umbonium vestiarium, when given a choice under laboratory conditions. This pattern was
signifi cant, and held for experiments regardless of whether prey were shelled or unshelled. Astropecten
indicus also consumed more M. senhousia than U. vestiarium when fed these prey ad libitum. This is
the fi rst study of its kind on A. indicus and thus contributes to the small pool of knowledge regarding the
ecology of this species.
KEYWORDS. Singapore, choice experiment, stomach contents, ingestion.
THE RAFFLES BULLETIN OF ZOOLOGY 2011 59(2): 251–258
Date of Publication: 31 Aug.2011
© National University of Singapore
INTRODUCTION
Sea stars (Echinodermata: Asteroidea) are ubiquitous
marine predators with diverse diets (Sloan, 1980) that play
functionally important roles in the benthos (Jangoux, 1982;
Ganmanee et al., 2003). Experimental studies on asteroid
predation since the mid 1960s (e.g. Paine, 1966) have shown
that these animals often dominate upper trophic cascades
(Jangoux, 1982). During his classic experimental removal of
Pisaster asteroids, Paine (1969) witnessed a complete change
in the intertidal community’s composition. Subsequent
studies further demonstrated that these keystone predators
exert a disproportional infl uence on community structures
(Paine, 1995).
The sand star Astropecten indicus (Döderlein, 1888), order
Paxillosida, family Astropectinidae, is widely distributed in
both intertidal and subtidal habitats throughout the world
(Peres, 1982). This penta-symmetrical sea star is usually
found in mud, sand, and shell habitats (Hopkins et al., 1994)
where it ingests a large number of bottom-dwelling animals
(Wells et al., 1961). The predation activities of Astropecten
species in soft sediments are known to infl uence the densities
of their infaunal prey (Christensen, 1970). Astropecten species
are able to distinguish the quality of their prey using their
chemoreceptive abilities (Sloan, 1980) and can therefore
preferentially select those with greater nutrient and energy
value (Beddington & McClintock, 1993).
The carnivorous diet of Astropecten sea stars involves
intraoral digestion, in which live prey are swallowed whole
(Hyman, 1955). Prey size is limited by the size of their
stomach and oral disc, leading to a preference for small prey
items (Lemmens et al., 1995) as compared to asteroid taxa
that digest extraorally. Sea stars of the genus Astropecten
are generalists, feeding on a wide variety of prey such as
crustaceans, polychaetes, sipunculids, pennatulids, ascidians,
sh, other echinoderms and even sediments (Sloan, 1980;
Jangoux, 1982; Wells & Lalli, 2003). Their main diet,
however, consists of shelled molluscs (gastropods and
bivalves) (Ribi & Jost, 1978; Town, 1980; Beddington &
McClintock, 1993; Ganmanee et al., 2003) that constitute
approximately 90% of the diet in Astropecten zebra and
about 75% of the diet in Astropecten velitaris (Lemmens et
al., 1995). The shells remain after the soft body parts have
been digested (Wells et al., 1961) and regurgitated prey
items provide a good indication of Astropecten diets (Wells
& Lalli, 2003).
The predator’s diet reflects, and is fundamental to, its
ecological niche (Sih & Christensen, 2001; Paine, 1966).
Diet preferences are influenced by factors such as prey
abundance and energy content (McClintock & Lawrence,
1985; Sloan, 1980). Emlen (1966) predicted that predators
will consume prey that are abundant even if they are less
preferred. Energy maximisation is also an important infl uence
252
Loh & Todd: Diet and feeding in Astropecten indicus
on feeding preference. In lobsters (Homarus americanus),
for example, there exists strong prey preference for small
crabs and molluscs instead of echinoderms, which tend to
have lower calorifi c content (Ojeda & Dearborn, 1991).
Prey selectivity is considered a signifi cant part of optimal
foraging models (Pulliam, 1974) refl ecting the effi ciency of
diet utilisation (Beddington & McClintock, 1993). A review
on the diet of most asteroids types showed that carnivorous
species are usually generalists (Jangoux, 1982) with a certain
level of prey selectivity. The feeding biology of asteroids
is a key component of the ecology of benthic communities
(Hatanaka & Kosaka, 1959; Gaymer et al., 2001) and the
evaluation of their feeding behaviour can provide a better
understanding of their impact as predators.
Astropecten indicus is one of the most common sea stars in
Singapore waters, where it reaches a maximum arm length
(centre to tip of 4th arm) of ~50 mm (pers. obs.). Despite its
abundance, knowledge on the biology and ecology of this
species is scarce (but one example is Riccio et al., 1987).
The large populations of A. indicus along Singapore shores
provide an excellent opportunity for more research on these
tropical asteroids and here we focus on their diet and prey
preference. First, the diet of A. indicus in its natural habitats
was examined via field sampling and stomach contents
analysis. Second, their feeding behaviour when presented with
the Asian date mussel Musculista senhousia and the button
snail Umbonium vestiariumn was determined in controlled
experiments. Third, the number of prey ingested, and ejected,
by A. indicus when fed M. senhousia and U. vestiariumn ad
libitum was measured.
MATERIAL AND METHODS
Study areas. – Four sandy bottom habitats along the eastern
Johor Strait of Singapore, where A. indicus is abundant,
were selected as fi eld study sites (Fig. 1). These were the
intertidal fl ats at Changi; Site 1 (103°59'11"E, 1°23'34"N),
Chek Jawa; Site 2 (103°59'E, 1°24'N) and two locations
at Pasir Ris; Site 3 and Site 4 (103°57'17"E, 1°22'59"N
and 103°56'21"E, 1°23'22"N respectively). The waters of
Johor Strait are nutrient rich and turbid, due to both river
and sewage discharge (Gin et al., 2006). River inputs from
Singapore and Johor also causes lower salinities (19–33‰,
mean ~28‰) compared to the Singapore Straits (28.7–32.2‰,
mean ~30.6‰) (Gin et al., 2006). The tides in the eastern
Johor Straits surrounding the study sites are semi-diurnal with
a range of 0.6 to 2.9 m above chart datum (MPA, 2009).
Diet analysis. During low spring tides between December
2008 and February 2009, the type of diet and prey size of
A. indicus in their natural environment was investigated at
all four sites. Sea stars (mean arm length of subsample =
24.60 mm ± S.E. 0.23, n = 40) were hand collected at the
intertidal zone and placed in separate plastic containers (6.5
× 5.0 cm; diameter × height) with fresh ambient sea water
for approximately 3 h; suffi cient time for the sea stars to
regurgitate their gut contents. Only hard prey items were
surveyed. The sea stars were later returned to the location Fig. 1. Map of north-eastern Singapore showing the four study sites
along the Eastern Johor Strait.
from which they were captured. Each regurgitated food item
was identifi ed to the lowest possible taxonomic level and its
maximum dimension recorded.
Collecting and maintaining the sea stars for experimental
work. – Astropecten indicus was collected at low tide at
the intertidal zone by hand between Jul.2008 and Feb.2009
from Changi and Pasir Ris and transported to the marine
aquaculture facility in the Tropical Marine Science Institute
(TMSI) on St John’s Island (103°50'60"E, 1°13'03"N),
Singapore. In rectangular glass-fi bre holding tanks (45 × 26
× 30 cm; length × width × height), sea stars were kept in
aerated and sand-fi ltered sea water in a fl ow-through system.
Based on temperature loggers (StowAway TidbiT) the mean
ambient water temperature was 29.39 ± S.E. 0.31°C. The
salinity range was 29 to 32‰ as measured by ABMTC
handheld refractometer. These parameters were the same
for all ensuing experiments. Each holding tank contained
a 3-cm layer of fi ne sand as substrate for the sea stars to
burrow in.
Prey choice experiment. – Prey choice was examined
using two common prey species: button snails, Umbonium
vestiarium, and Asian date mussels, Musculista senhousia.
Before each experiment, sea stars were conditioned by
starving them for a week. With-shell individuals of each
prey type were offered to A. indicus to study its preference.
In order to match the ‘value’ (dry flesh weight) of U.
vestiarium to M. senhousia, the relationship between U.
vestiarium maximum shell diameter and dry fl esh weight was
calculated using 30 specimens (dry weight of U. vestiarium
[g] = 0.0021 × diameter [mm] – 0.01; R = 0.86) with a size
range of 5.82 to 8.90 mm (mean 7.21 mm ± S.E. 0.84).
For M. senhousia, the equation for the shell length to dry
esh weight regression was derived from Crooks (1996).
Therefore, for both species, it was possible to predict (and
thus match) the dry fl esh weight of either species simply by
measuring their shell length (M. senhousia) or diameter (U.
vestiarium). This did, however, result in M. senhousia being
consistently larger (longer) than U. vestiarium in these trials.
The choice experiment was repeated, using the same two prey
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THE RAFFLES BULLETIN OF ZOOLOGY 2011
species, but with their shells removed (and the fl esh matched
for wet weight). For each of the prey choice experiments,
30 different sea stars were used. The two food items were
placed equidistant (10 cm) from the sea star and 8 cm apart
in a 2.2-L plastic tank (21 × 13 × 12 cm; length × width ×
height) fi lled with seawater to 10 cm height. Which species
was to the left or right of the sea star was alternated between
runs. Water was introduced into the tank ‘upstream’ so that
it fl owed past the prey items and towards the sea star. The
rst prey choice and the time taken (with S.E.) for the sea
star to select (ingest) it was recorded. Signifi cance of choice
was examined using Chi-square tests.
Ingestion experiment. – The ingestion experiment was
conducted by offering A. indicus (n=20) U. vestiarium (mean
length of subsample = 6.74 mm ± S.E. 0.09, n = 40) and
M. senhousia (mean length of subsample = 8.69 mm ± S.E.
0.15, n = 40) ad libitum. For each prey type, twenty 2.2-L
replicate tanks (same dimensions as for the prey choice
experiment) each containing one sea star and 40 prey were
used. The number of prey ingested was recorded twice: after
two hours, and again after 24 hours, by counting the number
of remaining prey alive. A t-test was performed to evaluate
the difference in the mean number of M. senhousia and
U. vestiarium ingested after two hours, plus another t-test
for the mean number ingested after 24 h. The relationship
between the number of sea stars that ejected prey and the
prey type (M. senhousia and U. vestiarium) was examined
with a Chi-square test. Finally, the correlation between the
number of prey items ingested after 24 h and sea star arm
length was calculated.
RESULTS
Diet analysis. – The stomach contents of 69 A. indicus were
examined from which 133 intact prey items were collected.
These items comprised 27 species (Table 1, Fig. 2) and had
a size range of 1.48 to 14.29 mm. Broken fragments were
excluded from the analysis because the number of individuals
could not be determined from these remains. Molluscs
comprised 94.74% of all hard prey (n=133) while arthropods
accounted for 3.76%. There were twice as many species
of gastropods (16 species) than bivalves (8 species), but a
slightly higher number of bivalve individuals were recorded
(64 bivalves vs 62 gastropods). Musculista senhousia was the
dominant prey (36.09%) among all regurgitated items; it was
also the only prey type recorded at all four study sites. There
were signs such as discoloration and worn broken edges on
the dead shells of Cerithium species (Fig. 2) suggesting that
these were consumed by A. indicus by accident, or for the
living occupants of the shells, i.e. hermit crabs or barnacles
(Wells et al., 1961).
Prey choice experiment. – Most of the sea stars did not
immediately make a decision between the two prey choices,
with mean time before consumption being 134 ± 14 s for
without-shell prey and 163 ± 23 s for with-shell prey. For
the experiment between with-shell M. senhousia and with-
shell U. vestiarium, signifi cantly more sea stars chose M.
senhousia rst (χ2=4.80; d.f.=1, P<0.05) (Fig. 3a). Similar
results were found for the experiment between without-shell
M. senhousia and without-shell U. vestiarium (χ2=6.53;
d.f.=1, P<0.05) (Fig. 3a).
Ingestion experiment. – The number of M. senhousia and
U. vestiarium ingested per sea star ranged from 6 to 25
and 2 to 17 respectively. Signifi cantly more M. senhousia
had been ingested compared to U. vestiarium after 2 h (t=-
4.767, d.f.=19, p<0.001), and after 24 h (t= 7.647, d.f.=19,
p<0.001) (Fig. 3b). By the 24 h mark, 12 sea stars had
ejected U. vestiarium compared to only one that ejected M.
senhousia (χ2=13.79, d.f.=1, P<0.001). The stomach of A.
indicus expanded dramatically after being fed ad libitum
(Fig. 4). There were signifi cant positive correlations (one-
tailed tests) between the number of prey ingested at 24 h
and A. indicus arm length, with a stronger correlation for M.
senhousia (R=0.655, p<0.001) as compared to U. vestiarium
(R=0.392; p<0.05) (Fig. 5).
DISCUSSION
Availability of food is one of the main factors determining
the behaviour, distribution and abundance of species (Gaymer
et al., 2001). Intraoral digestion in Astropecten sea stars
facilitates the easy investigation of stomach contents and
thus their feeding habits (Jangoux, 1982). Similar to other
Astropecten diet analyses (Ribi & Jost, 1978; Wells & Lalli,
2003), the dominant (94.74%) phylum found in the stomach
of A. indicus was Mollusca. A review by Christensen (1970)
showed that almost all Astropecten species, with the possible
exception of A. johnstoni, feed mainly on molluscs. Even
though A. indicus consumed a total of 27 species, there was
a very high percentage (36.09% of total prey items) of M.
senhousia. From the Changi and Pasir Ris study areas, 10
M. senhousia were recovered from each site, whereas only
one M. senhousia was regurgitated from Chek Jawa. There
were, however, far fewer mussel beds at Chek Jawa compared
to the other study sites (pers. obs).
The number of bivalves ingested was higher than that of
gastropods, but the species diversity of the latter was greater.
These included eulimid (family Eulimidae) and pyramidellid
gastropods (family Pyramidellidae), potential parasites of A.
indicus. Echinoderms are known to host ~800 ectoparasitic
species from the family Eulimidae (Waren, 1984), but, even
in large aggregations, these do not cause mortality (Jangoux,
1987). Asterolamia hians, a common eulimid gastropod, is
known to feed on the aboral surface of A. indicus (Waren,
1980). Pyramidellidae are also often parasitic, but possess
a certain degree of host specificity (Robertson & Mau-
Lastovicka, 1979). Further work is required to determine
whether any of the gastropods regurgitated by A. indicus
are parasitic.
The prey choice experiment demonstrated that A. indicus
selected M. senhousia over U. vestiarium, even though the
M. senhousia were larger (maximum linear dimension). In
addition, the ingestion experiment showed that A. indicus
254
Loh & Todd: Diet and feeding in Astropecten indicus
Table 1. Species regurgitated by A. indicus collected at four sites (1=Changi, 2= Chek Jawa, 3= Pasir Ris Location 1, 4= Pasir Ris).
Site (No. sea stars that regurgitated)
Taxon Family 1 (12) 2 (20) 3 (16) 4 (21) Total Percentage (%) Rank
MOLLUSCA
Bivalvia
Musculista senhousia Mytilidae 10 1 14 23 48 36.09 1
Anomalocardia squamosa Veneridae 5 5 3.76 6
Venerid bivalve 1 Veneridae 1 1 2 4 3.01 7
Tellinid bivalve Tellinidae 2 1 3 2.26 8
Dosinia sp. Veneridae 1 1 0.75 9
Venerid bivalve 2 Veneridae 1 1 0.75 12
Anadara sp. Arcidae 1 1 0.75 12
Mactrid bivalve Mactridae 1 1 0.75 12
Total bivalves 13 7 19 25 64 48.12
Gastropoda
Rissoid gastropod Rissoidae 2 1 15 18 13.53 2
Pyramidellid gastropod 1 Pyramidellidae 12 12 9.02 3
Trochoid gastropod Trochidae 4 3 7 5.26 4
Umbonium vestiarum Trochidae 6 6 4.51 5
Eulimid gastropod Eulimidae 3 1 4 3.01 7
Stenothyra sp. Stenothyridae 2 1 3 2.26 8
Batillaria sp. Batillariidae 2 2 1.50 9
Cerithium sp. Cerithiidae 1 1 2 1.50 9
Nassariid gastropod Nassariidae 1 1 0.75 9
Pyramidellid gastropod 2 Pyramidellidae 1 1 0.75 10
Clithon oualaniensis Neritidae 1 1 0.75 10
Costellariid gastropod Costellariidae 1 1 0.75 10
Acteonid gastropod Acteonidae 1 1 0.75 10
Iravadia sp. Iravadiidae 1 1 0.75 10
Haminoea sp. Haminoeidae 1 1 0.75 10
Pseudoliotia sp. Vitrinellidae 1 1 0.75 10
Total gastropods 7 31 18 6 62 46.62
ARTHROPODA
Crustacea
Balamus sp. Balanidae 3 3 2.26 7
Crab cheliped Unknown 1 1 0.75 9
Calappid crab cheliped Calappidae 1 1 0.75 10
Portunid crab leg Portunidae 0 0.00 10
Total crustaceans 1 1 0 3 5 3.76
OTHERS
Dead Cerithium sp. before ingestion 2 2 1.50 9
Total prey 21 39 37 36 133
was able to consume more M. senhousia than U. vestiarium
after two and 24 hours of prey introduction. Finally, A.
indicus was observed to eject live U. vestiarium after
consumption. All these fi ndings suggest A. indicus prefers
M. senhousia over U. vestiarium. Other sea stars, such as
Luidia clathrata, have similar strong prey preference for one
species (e.g. L. clathrata prefers the bivalve Mulinia lateralis)
despite ingesting a wide range of organisms (McClintock &
Lawrence, 1985).
The degree of diet specialisation usually depends on the
stability of the environment. An unstable environment will
often lead to a more generalised diet (Klopfer, 1959) while
a stable environment (one where the preferred prey is more
readily available across spatial and temporal scales) facilitates
specialisation (Connell, 1970). The relative degree of diet
specialisation will change according to the fluctuations
in the abundance of the preferred prey (Emlen, 1966).
Musculista senhousia populations are known to experience
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THE RAFFLES BULLETIN OF ZOOLOGY 2011
Fig. 2. Examples of 16 prey types found in the stomachs of Astropecten indicus (n = 69) collected in Singapore. The white bar at the bottom
right of each item = 1 mm. *Cerithium sp. was dead before ingestion.
episodic high mortality (Crooks, 1996), therefore A. indicus
probably requires the ability to switch feeding habits
between the dominant preferred species and a wide range
of other molluscan prey (Town, 1980; Wells & Lalli, 2003).
Astropecten scabra also showed similar foraging strategies
where feeding, growth and reproduction homeostasis was
maintained even when their preferred prey species was less
available (Town, 1980).
The flexibility of a sea star’s stomach is important to
determining the number of prey it can digest ad libitum.
Due to its elastic dorsal body Astropecten articulatus can
increase its stomach-capacity by up to 43% (Beddington
& McClintock, 1993). An individual A. articulatus of arm
length 35.4 mm was observed to ingest 10 bivalves ranging
from 8.8 to 12.4 mm within 20 min (Christensen, 1970). In
the present study, on average, A. indicus (mean arm length
26.4 mm, n=20) ingested 14 M. senhousia ranging from
256
Loh & Todd: Diet and feeding in Astropecten indicus
Fig. 5. Scatter plot showing the relationship between number of
prey items ingested and Astropecten indicus (n=20) arm length
after 24 h.
Fig. 3. a) Number of Astropecten indicus that chose with-shell
and without-shell Umbonium vestiarium and Musculista senhousia
prey (n=30). b) Mean number + S.E. of prey ingested at 2 h and
at 24 h. Differences between light and dark bars are signifi cant
for both a) and b).
Fig. 4. Stomach packing of A. indicus after ingesting Umbonium
vestiarium ad libitum.
7.5 to 10.2 mm within two hours. Smaller sized prey are
preferred by A. articulatus due to the stiff architecture of its
oral frame (Beddington & McClintock, 1993). Conversely, A.
irregularis can ingest large prey due to their highly fl exible
mouth (Christensen, 1970). The length of the mactrid bivalves
(family Mactridae), the largest prey recorded in the diet of A.
indicus, is approximately four times greater than the diameter
of its oral orifi ce, suggesting that A. indicus is capable of
extending its mouth opening. This should help A. indicus
increase the breadth of its diet by including a larger range
of prey sizes—potentially useful during low availability of
smaller prey.
Due to the ease of handling and ingestion, sea stars with
intraoral digestion prefer smaller prey compared to larger
prey of similar dry weight (McClintock & Lawrence, 1985;
Beddington & McClintock, 1993). Shorter handling time
helps maximise food intake per unit time (Campbell, 1987).
However, in the present study, the shell length of selected M.
senhousia was consistently longer than U. vestiarium for the
same dry weight of fl esh. According to optimal diet theory,
high calorifi c values are usually chosen as they can yield
more energy per unit time (Sih & Christensen, 2001). But,
M. senhousia has a slightly lower calorifi c content of 17.6 kJ
g-1 (Oka et al., 1999) compared to U. vestiarium’s of 20.1 kJ
g-1 (Berry, 1983). Thus, neither shell size nor calorifi c content
explains A. indicus preference for M. senhousia. Calorifi c
yield can, nonetheless, be of secondary importance to prey
availability (Town, 1980). Prey availability is directly related
to ingestion conditioning, i.e. the predator selecting for a
particular prey because it has been feeding on it for some time
(Christensen, 1970). Ingestion conditioning may account for
the preference for M. senhousia in the choice experiment as
it appears that A. indicus has been disproportionately exposed
to this mussel species.
The prey preference for M. senhousia and the high number
ingested by A. indicus may serve an important ecological
role in the benthic community. Musculista senhousia is an
opportunistic and gregarious mytilid native to the Indo-Pacifi c
region (Crooks, 1996; Mistri, 2004). Although small as an
individual, M. senhousia forms extensive mats which can
predominate and alter benthic habitats (Creese et al., 1997;
Yamamuro et al., 2000; Mistri, 2004). Furthermore, they
have a high growth rate and often occur in huge numbers
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THE RAFFLES BULLETIN OF ZOOLOGY 2011
(Crooks, 1996). Sea star predation is an important factor in
controlling populations of mussels (Yamamuro et al., 2000;
Gaymer & Himmelman, 2002) and the feeding preference
and high ingestion limit for M. senhousia by A. indicus
should help promote habitat heterogeneity and higher species
diversity by preventing mussel beds dominating intertidal
soft sediments.
ACKNOWLEDGEMENTS
Many members and staff of the Marine Biology Laboratory
and the Tropical Marine Science Institute provided facilities
and assistance, especially Prof. Chou Loke Ming, Dr. Tan
Koh Siang, Neo Mei Lin, Ow Yan Xiang, Poquita Rosa
Celia, and Chim Chee Kong. Prof. John Lawrence and Dr.
David Lane kindly shared their expertise of sea stars. The
National Parks Board facilitated the work under the research
permit NP/RP824. This study was supported by Singapore’s
Ministry of Education’s AcRF Tier 1 funding: grant number
R-154-000-414-133.
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... Preyed item was identified to the lowest possible taxonomic level. Percent of occurrence was calculated using this formula by Loh and Todd (2011): ...
... This suggests that the juvenile A. planci are found out to be more cyptic, with an age ranged of 0.5 year to 2 years while the coral feeding adults the age ranged from 2 years to 5 years . Availability of food is one of the main factors in determining the behavior, distribution and abundance of the species (Gaymer et al., 2001;Loh & Todd, 2011). ...
... In this study, five seaweed species; Cyptonemia crenulata, Gracilaria spp., Halimeda macroloba, Padina gymnospora, Sargassum polycystum and one sea grass species; Cymodocea serrulata were also found in the gut of A. planci. These seaweed and sea grass species are characterized by having soft tissues which suggests that it can be easily digest since the flexibility of a sea star's stomach is important in determining the number of prey it can digest (Loh & Todd, 2011). The selectivity of prey is influenced by several factors such as the prey size which depends on its body size and constraints imposed by the mechanism of intraoral digestion (Ventura et al., 2001). ...
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Coral reef degradation is the major consequence posed by the massive infestation of Acanthaster planci (crown of thorns), a corallivorous sea star. This present study assessed the bioecological aspects of A. planci in terms of its morphology, coral type preference, gut analysis and physico-chemical parameter preferences on the coastal areas of Saloagan, Dimataling, Zamboanga del Sur. Two color morphs were exhibited by A. planci among the 90 individuals collected. The largest body size in diameter was 270mm, weighing 365g and with 7-16 number of arms. There were 14 identified coral species foraged by A. planci where Porites is the most preferred coral genus preyed by 23.33% of the A. planci studied. Gut analysis revealed fragments of coral species such as Pocillopora spp., Acropora spp., five algae species, one sea grass species and unidentified species of crabs, gastropods and bivalves were found in the stomach of A. planci. All of the physico-chemical parameters obtained in Saloagan, Dimataling are within the same range compared to other areas where outbreaks of A. planci have been reported which indicate that the conditions in this local habitat are suitable for the growth of A. planci. This study may be significant in establishing management strategies to predict or possibly inhibit the outbreaks of A. planci on the coral communities.
... Seastar, Astropecten indicus (Phylum: Echinodermata: Class: Asteroidea: Order: Paxillosida), a generalized feeder is geographically distributed along the coast of South-East Asian countries including the coast of Bay of Bengal, India (Loh and Todd, 2011). Coastline of India, including Bay of Bengal is reported to be contaminated by various types of MPs (Tiwari et al., 2019). ...
... Seastars with average diameter of 2.4 ± 0.3 cm, were acclimatized in glass aquaria consisting artificial sea water (ASW) and sand sediments with adequate aeration and filtering system at a density of single specimen per 3 L of sea water at constant temperature range (15− 22 • C), salinity (33 PSU) and pH (8.0-8.1) for 7 days. Both control and treated specimens were fed with chopped flesh of Asian date mussel, Musculista senhousia (Loh and Todd, 2011) at every 24 h of interval and water quality parameters were monitored routinely. Prior to feeding, chopped flesh of mussel were evenly spread over sand surface of the aquaria. ...
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Microplastics (MPs) are established contaminants of coastal ecosystem. Present investigation is aimed to assess comparative toxicity of polystyrene microplastic (PS-MP) and expanded polystyrene microplastic (EPS-MP) in the coelomocytes of Astropecten indicus, a common seastar of Digha coast of Bay of Bengal, India. Coastal water of Digha, a tourist spot of attraction, bears the ecotoxicological risk of contamination by various agents including expanded and nonexpanded microplastics of industrial origin. Coelomocytes of seastar perform multiple physiological functions including pathogen engulfment, cytotoxicity and respiratory gas exchange and considered as immunoeffector cells in echinoderms. We report an adverse shift in total count, phagocytic response, cytotoxicity and oxidative potential of the coelomocytes of A. indicus under the exposures of 0.5 and 1 mg L⁻¹ PS-MP and EPS-MP for 7 and 14 d. Experimental data suggested a higher level of cytotoxicity of EPS-MP in coelomocytes in comparison to that of PS-MP. Seastar is considered as a keystone species, which plays an important role in maintaining the functional homeostasis of coastal ecosystem. Unrestricted contamination of coastal water by MPs may lead to a persistent immunophysiological stress in seastar. Experimental endpoints may be considered as effective monitoring tool to assess ecotoxicity of MPs in seastar and alike organisms sharing the same habitat.
... In sandy and muddy subtidal habitats, starfish present a variety of feeding strategies, including scavenging and deposit and suspension feeding (Hendler et al., 1995;Gaymer et al., 2004). In addition, starfish actively prey on a wide variety of organisms, including mollusks, crustaceans, polychaetes, sipunculids, pennatulids, ascidians, fish, and other echinoderms (Monteiro and Pardo, 1994;Wells and Lalli, 2003;Gil and Zaixso, 2008;Loh and Todd, 2011). The coexistence of several species (e.g. ...
... Our identification analysis using the highest taxonomic separation possible was essential to verify the dietary similarities between the two sympatric starfish species evaluated here: Astropecten marginatus Gray, 1840 and Luidia senegalensis (Lamark, 1816). These two species feed on a wide variety of prey, with a preponderance of macro-invertebrates as already described for other starfish (e.g., Terborgh et al., 1999;Loh and Todd, 2011;Monteiro and Pardo, 1994). As these starfish share the same habitat, they generally feed on the same food types. ...
Article
Starfish are important predators that may shape rocky shore communities, but their ecological role in unconsolidated substrate communities is still poorly known. We assessed the feeding niche overlap of two sympatric starfish, Astropecten marginatus and Luidia senegalensis, from the shallow subtidal zone in southeastern Brazil. During one year, we conducted monthly samples to compare diet composition, abundance and frequency of occurrence of each food item between species. With 24 of the 34 food items identified in this study consumed by both species, they exhibited generalist behaviors, with a more diverse diet during the warm periods, when the main prey items were abundant. However, A. marginatus showed more variation in abundance of prey consumed over time than L. senegalensis. The diet of A. marginatus consisted primarily of the bivalve Tivela mactroides and L. senegalensis of the bivalve Mulinia cleryana. The size of T. mactroides was positively correlated to the size of A. marginatus, while only small-sized individuals of L. senegalensis consumed this item, the most abundant prey in the area and an important food resource for local the community. The large quantity and variety of items consumed by both species support the structuring role of starfish in subtidal unconsolidated substrate communities, exerting a generalist top-down control, primarily on dominant bivalve populations. Temporal variation in the availability of the main prey may change how selective are both species. The differences in prey composition between species and the ontogenetic differences in prey selectivity by L. senegalensis may attenuate interspecific competition, facilitating their coexistence.
... The prey selection will be changed based on the abundance of prey in the niche [21]. About 83.67% of S. childreni fed on benthic foraminiferans. ...
... Molluscs usually burrow and stay inside the sediments and thus matched feeding behaviour of S. childreni. Other Asteroidea researchers [21] reported that shelled molluscs (gastropod and bivalve) served as main diet of approximately 90% Astropecten zebra and 75% of A. velitaris. In this study, detailed examination on the gut content related to molluscs revealed that gastropod juveniles had frequency occurrence of 44.89%, followed by bivalve juveniles (12.24%) and scaphopod juvenile (4.08%). ...
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Sea star (Class Asteroidea, Phylum Echinodermata) is one of the most successful marine organisms inhabiting a wide range of habitats. As one of the key stone species, sea stars are responsible for maintaining much of the local diversity of species within certain communities. Malaysian Exclusive Economic Zone (EEZ) Resource Survey had been carried out from 16th Aug to 6th Nov 2015 and one of the invertebrate by-catch organisms is sea star Stellaster childreni Gray, 1840. This study documents morphological characters and diet of the sea star, besides providing brief descriptions of the habitats based on particle size analysis and vessel log data sheet. A total of 217 individuals had been examined throughout this study. Fragments of flora and fauna were found in the gut including Mollusca (gastropod, bivalves and scaphopods), sponge seagrass and seaweed as well as benthic foraminifera. Stellaster childreni were found at depth of 45 m to 185 m in the South China Sea off Sarawak Malaysia, with various sea bottom substrata. Approximately 41 % of S. childreni were found at a mixture of sandy and muddy substratum, followed by mixture of sandy and coral (19.3%), muddy substratum (17.5%), coral substratum (11.5%) and sandy areas (10.6%). The widely distributed sea star on different types of sea beds suggested healthy deep sea ecosystem, thus Malaysia should explore further potential fisheries resources in the EEZ off Sarawak coast.
... Members of the family Astropectinidae, including the genus Astropecten (Gray, 1840), inhabit tropical, subtropical and temperate waters (Bitter & Penchaszadeh, 1983;Soto, 2000;Loh & Todd, 2011). This genus is exclusively carnivorous and an active predator with a generalist diet, and has negative effects on the density of its prey (Jangoux, 1982). ...
... Regarding feeding behavior on the genus Astropecten, several studies conducted worldwide have found primarily mollusks, especially bivalves (Christensen, 1970;Penchaszadeh, 1973;Nojima, 1988Nojima, , 1989Freeman, Richardson & Seed, 1998;Brogger & Penchaszadeh, 2008;Loh & Todd, 2011) and gastropods (Soto, 2000, Ganmanee et al., 2003Juan, Cartes & Demestre, 2007) as main prey. The same feeding pattern has also been observed for A. marginatus inhabiting the Caribbean Sea (Soto, 1984;Ortega et al., 2011) and Brazil (Monteiro & Pardo, 1994). ...
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The sea star Astropecten marginatus has a neotropical distribution and is a highly abundant and frequent species in shrimp trawling by-catchin many places along the Brazilian coast. This has caused its threat to extinction and in addition, its bio-ecological aspects are poorly known. Thus, the main objective of this study was to analyze the seasonal variations of population length structure and feeding habits of the sea stars A. marginatus inhabiting off state of Parana, Southern Brazil. The analyzed specimens were collected in February (summer), April (fall), June (winter) and October (spring) of 2008 from shrimp by-catch trawling. in the labora- tory, each individual had its length measured and then weighed on an analytical scale. Afterwards, the stomach contents of 10 individuals of each of two most frequent length classes were seasonally analyzed. The relative frequency and abundance for each prey category was determined and, then combined into an index of alimentary importance. A total of 994 individuals of A. marginatus were collected with length ranging from 7.0 to 56.2mm, but most individuals were in the 20.1-25mm length classes. individuals larger than 40mm were only collected in the spring while a few recruits (<10mm) were found in fall and winter. The total weight of individuals ranged from 0.1 to 15.3g and the weight-length relationships showed a negative allometric growth (b<2.54). Regarding its food consumption, this sea star explored eleven food items, with cumaceans and mollusks as the most fre- quent items. High frequency of empty stomach was recorded at fall. Seasonal differences in the amount explored preys and ingested items as well as in the prey composition were also observed. Higher amount of explored prey categories and ingested items were recorded at winter-spring than summer-fall periods. Predominance in prey category changed from gastropods (summer and fall) to cumaceans (winter and spring). The importance of gastropods as main prey category at summer and fall should be carefully considered since it was coincidently observed with high frequency of empty stomach and low amount of ingested items. The observed seasonal dif- ferences in feeding behavior pattern were mainly associated to low prey availability and to changes in the sea star feeding rates, and probably reflected in some biological traits such as small body size of the population inhabiting waters off the Parana coast, Southern Brazil. Rev. Biol. Trop. 62 (1): 59-68. Epub 2014 March 01.
... Sea stars are common invertebrates in benthic communities, acting as omnivorous, opportunistic (Martín et al., 2001), predatory, herbivorous, detritivorous or scavenging species (Dayton et al., 1974;McClintock, 1994;Gil and Zaisxo, 2008;Loh and Todd, 2011). In the Southern Ocean and southern South America, the genus Odontaster is represented by five species of sea stars: Odontaster meridionalis (E.A. Smith, 1876), O. validus (Koheler, 1906), O. penicillatus (Phillipi, 1870), O. pearsei (Janosik and Halanych, 2010) and O. roseus (Janosik and Halanych, 2010) Halanych 2010, Janosik et al., 2011). ...
Article
We report for the first time the presence of local populations of the starfish Odontaster penicillatus in the regions of Atacama and Antofagasta, Chile. This finding indicates an extension of the distribution limit of 500 km with respect to the last observation made in 2007 in Isla Grande de Atacama. A total of 121 specimens of O. penicillatus were recorded at depths of between 8 m and 24 m. They were associated with rocky substrate and with different species of barnacles, sponges and bryozoans. The presence of O. penicillatus expands the knowledge of the benthic biodiversity of the region, and the development of studies on its ecological importance will be promoted. Keywords: Odontaster penicillatus, new record, Antofagasta, Atacama, South Pacific Ocean
... El valor de diversidad de la estación C2 (H'= 0.38 bits ind -1 ) fue inferior al reportado para áreas perturbadas (0.8 bits ind -1 ; Jones et al. 2006), debido a una elevada abundancia de organismos de la especie A. cingulatus (37.9 10 3 ind km -2 ), la cual es reportada como especie clave que determina la composición de especies macrofaunales por predación, influyendo en la dieta de otros carnívoros presentes en el área (Loh & Todd 2011); siendo responsable del 96% de la abundancia de una comunidad compuesta mayoritariamente por organismos que son sus frecuentes ítem alimenticios (e.g. crustáceos y moluscos; Bitter & Penchaszadeh 1983, Lawrence 2014. ...
Thesis
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Los atributos comunitarios son el conjunto de características estructurales y funcionales que permiten definir comunidades espacial y temporalmente. Dichos atributos se evaluaron en comunidades megabentónicas capturadas en maniobras con redes de arrastre de fondo, realizadas en los cruceros oceanográficos Gomex IV (GIV), Gomex V (GV), Perdido II (PII) y Perdido III (PIII), llevados a cabo en los márgenes externos de la plataforma de Yucatán (MEPY) y el Cinturón Plegado Perdido (CPP), durante noviembre de 2015 a junio de 2017; donde fueron evaluadas ambientales de fondo y las características químicas y texturales del sedimento. En los MEPY las variables oceanográficas de fondo, tipo de sedimentos e hidrocarburos fueron los principales gradientes ambientales; mientras que en el CPP lo fueron las variables oceanográficas de fondo, el contenido de carbono, hidrocarburos y metales almacenados en sus sedimentos terrígenos. Fueron capturados 174,811 individuos y 273,693 kg AFDW (peso seco libre de cenizas en su acrónimo en inglés), distribuidos en 459 especies. El 82% de los organismos se capturaron en los MEPY, donde los grupos más importantes fueron crustáceos, moluscos y poríferos, mientras que en el CPP lo fueron los crustáceos y equinodermos. Periclimenes iridescens y Astropecten cingulatus fueron las especies más abundantes (104.5 103 ≤ ind km-2 ≤ 136.3 103), mientras que Callinectes sapidus y Panulirus argus exhibieron los valores más altos de biomasa (137.6 ≤ kg AFDW km-2 ≤ 209.1). Los MEPY no exhibieron gradientes asociados con la distribución espacial ni la profundidad, mientras que el gradiente batimétrico fue determinante en la fauna del CPP. Los valores de diversidad local de los MEPY fueron mayores a los del CPP (2.88 ≤ bits ind-1 ≤ 5.31 bits ind-1, 0.35 ≤ bits ind-1 ≤ 3.69), esta última área presentó mayor diversidad beta que los MEPY (0.86 y 0.85 respectivamente); siendo este un patrón típico de ambientes con distribuciones agregadas. Los MEPY presentaron mayor estabilidad, diversidad regional y funcional que el CPP (Δ+-Δ+=86.76-430.40 y Q=0.43±0.23; Δ+-Δ+=90.02-250.53 y Q=0.48±0.20, respectivamente); patrón atribuido a una mayor influencia de las actividades económicas sobre la fauna del CPP, favoreciendo menor sensibilidad y mayor resiliencia ante actividades de arrastre evidenciado en los índices TDI. BESITO y RTI. Los índices BAMBI y M-BAMBI indicaron de manera preliminar altas condiciones ambientales y ausencia de disturbios. Se recomienda adelantar programas de protección en los MEPY y programas de monitoreo en el CPP, a fin de mantener y mejorar las condiciones de las áreas evaluadas.
... Organisms prefer more generalised food in an unstable environment (Klopfer, 1959) while a relatively stable environment facilitates specialisation (Connell, 1970). Recent studies about the feeding behaviour of A. indicus indicate that they prefer very quality food in their diet and they ingested more number of bivalves in their diet (Loh and Todd, 2011). In the present study a sandy shore ecosystem (Muzhuppilangadu beach, South West coast of Kerala, India) investigated and revealed the trophic relation between A. indicus and the spats of D. incarnatus. ...
... Organisms prefer more generalised food in an unstable environment (Klopfer, 1959) while a relatively stable environment facilitates specialisation (Connell, 1970). Recent studies about the feeding behaviour of A. indicus indicate that they prefer very quality food in their diet and they ingested more number of bivalves in their diet (Loh and Todd, 2011). In the present study a sandy shore ecosystem (Muzhuppilangadu beach, South West coast of Kerala, India) investigated and revealed the trophic relation between A. indicus and the spats of D. incarnatus. ...
... Organisms prefer more generalised food in an unstable environment (Klopfer, 1959) while a relatively stable environment facilitates specialisation (Connell, 1970). Recent studies about the feeding behaviour of A. indicus indicates that they prefer very quality food in their diet and they ingested more number of bivalves in their diet (Loh and Todd, 2011). In the present study a sandy shore ecosystem (Muzhuppilangadu beach, South West coast of Kerala, India) investigated and revealed the trophic relation between A. indicus and the spats of D. incarnatus. ...
Conference Paper
Full-text available
In the present study, diversity of macrofauna and the factors influencing their occurrence in the soft bottom intertidal ecosystem of Muzhappilangad beach (Lat. 11˚47′55″N and Long. 75˚ 26′27″ E), southwest coast India were investigated. Two consecutive samplings were undertaken, one during premonsoon (February – May, 2013 and monsoon (June - September 2013). Sampling was conducted along three transects (Infra-littoral zone, middle zone and supra-littoral zone) using a quadrate with an area of 0.25m2 . Bivalves (Donax incarnatus), crustaceans (Emerita sp., Pagurus sp.) and polychaetes were the major groups recorded during pre-monsoon. During monsoon, this particular ecosystem was characterised by the presence of star fish Astropecten indicus and large number of spats of Donax incarnatus. A. indicus was of the size range between 5 – 8 cm. They were able to burrow and hide beneath the mud or sand. D. incarnatus were filter feeders and were able to shift with respect to the tidal level and burrow inside the sand. Collected specimens of A. indicus were preserved in 10% formalin and gut content was analysed to find out the trophic relation between the occurrence of this species and the Donax spats. Presence of enormous number of Donax spats (900/m2 ) during monsoon indicated that their breeding occurred during this season and large amount of organic matter deposition on the beach favoured their feeding and spawning. In the gut content analysis of A. indicus, undigested spats of D. incarnatus were found. This clearly indicates the predator-prey relationship between A. indicus and D. incarnatus.
Article
As other species of Astropecten, A. irregularis rests buried in the substrate between periods of feeding activity. These usually occur at twilight hours. The sea-star can sense and localize prey buried underneath it with great precision. Prey animals are quickly pushed through the mouth opening and into the stomach by the (sucker-less) tube feet surrounding the mouth. Astropectcn cannot dig deep enough to seize deep-sitting prey such as e. g. members of the Tellinidae and non-juvenile Mya spp. It feeds mainly on small animals, but may occasionally swallow very large prey. Digestion of prey takes place in pockets of the stomach wall and requires that lobes of the stomach can be inserted and applied in direct contact with the digestible tissue.Protected prey organisms such as bivalves with tightly appended valves cannot be digested before they succumb and start to gape permanently due to a lack of oxygen. Since oxygen requirements differ, prey are retained in the stomach for varying periods of time. Whereas Spisula subtruncata, for example, is digested and the empty shells ejected well within 24 hours, specimens of (non-juvenile) Venus gallina and Corbula gibba may be retained for 2-3 weeks or more. Certain prey as e.g. non-juvenile Natica spp., V.gallina of all sizes and C.gibba more than 2-3 mm long may often be ejected alive after a shorter or longer stay in the sea-star stomach. Astropecten is a selective feeder, mainly engulfing bivalves, among which it exhibits a distinct preference for species with a low resistance to anaerobic conditions. This behaviour and a pronounced tendency to feed primarily on juvenile specimens ensure that the digestible matter of swallowed prey in most cases may be quickly assimilated. Metabolic rate may seemingly be used as an index for attractiveness of bivalve prey, but the real stimulus is probably one or several metabolic end products. Food uptake is significantly reduced in the absence of “first class” food species. If only highly undesirable food species are present, the sea-star may almost stop feeding and loose weight. A medium sized Astropecten may pick up and digest more than 400 S.subtruncata spat within 24 hours and theoretically destroy some 30,000 spat annually. Among other bivalves taken in considerable numbers are Mya truncata and Montacuta ferruginosa. Newly settled Echinocardium cordatum are also heavily preyed upon, at least when attractive molluscan species are absent or scarse. In Danish waters feeding practically stops below 4°C. Above this temperature the feeding rate depends highly on the density and types of potential prey spesies present. In the 0resund, for example, feeding rates are usually low at the most favourable temperature level because such attractive prey as 0-group S.subtruncata are exterminated while the tempereture still is low. This results in undernourishment and stops reproduction. At 11-16° C, small specimens fed on attractive prey may daily consume an amount of food equal to about 18 % of their own living weight, whereas adult specimens consume considerably less, i.e. about 2 %. Data from the literature indicates that the majority, if not all, of the Astropecten spp. probably are selective feeders which mainly feed on molluscs.
Chapter
A key premise of optimal foraging theory is that animals have, through the process of natural selection, evolved behaviors that tend to maximize their rate of energy intake (see Pyke, Pulliam, & Charnov 1977; Krebs 1978, for reviews). Therefore, a predator determines the relative costs and benefits of feeding on different prey types, and chooses the prey type that maximizes food value and predator survival. The predator does not necessarily make conscious decisions (Krebs 1978). Rather, the decision is the result of partially or wholly genetically controlled behavior shaped by evolution.
Article
The stomach contents of 124 Astropecten articulatus have been identified and discussed. This starfish ingests great numbers of small sand-dwelling organisms. Ninety-one species of invertebrates were recovered, of which 73 were molluscs. The gastropods Acteocina candei, Natica pusilla and Olivella mutica comprised over 60% of the animals recovered. Astropecten articulatus apparently ingests whatever animals or shells it encounters. Because it effectively samples tiue fauna of offshore sand bottoms, its use is recommended as a collection tool for the study of this community.
Article
Extended spectroscopic analysis has led to the derivation of structure for a novel steroidal glycoside isolated from the starfish ; this compound, named indicoside A, contains a 5-0-methyl-β-galactofuranosyl moiety linked to C-28 of 24-methyl-5α-cholestane-3β,6α,7α,8,15β,24, 28-heptanol aglycone (1).
Chapter
Food resources are tabulated and discussed and trophic groups identified. Asteroidea often act as top carnivores in their benthic communities. Feeding mechanisms are examined: intraoral and extraoral types are distinguished, and capture of motile, slow-moving, sedentary and attached prey is described. Ciliary feeding is also noted. Digestion time, feeding rate and feeding rhythm are reviewed.-P.J.Jarvis
Article
On San Juan Island, Washington, three species of intertidal barnacles (Balanus glandula, Balanus cariosus and Chthamalus fissus) are the main prey of several species of predators, the commonest being three species of snails, Thais emarginata, Thais canaliculata and Thais lamellosa. Larvae of B. glandula settle throughout the intertidal zone but, except in quiet bays, survive to maturity only in a narrow zone at the top of the shore. In quiet bays, where predators of barnacles were scarce, and in areas of turbulent water where predators were excluded by other circumstances, adult B. glandula occurred over the whole intertidal zone. From the lower part of the intertidal zone. Predators were evidently eliminating all B. glandula from the lower part of the intertidal zone. The rates of feeding of Thais lamellosa and Thais emarginata were measured in cages on the shore. The existing population of Thais could account for all of the mortality of B. glandula which occurred at low shore levels in mid and late summ...