No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Ontogenetic diet shift and feeding activity in the temperate reef fish Cheilodactylus fuscus
Abstract
The red morwong, Cheilodactylus fuscus, is a large and conspicuous temperate reef fish of south-eastern Australia and is a popular target of spearfishers as well as an indicator species of bioaccumulation for water quality authorities. C. fuscus is a benthic carnivore, feeding on crustaceans, polychaetes and molluscs. Amphipods and other small benthic crustaceans (tanaids, cladocerans, cumaceans and mysids) constitute over 60% of the diet of juvenile fish (<200 mm standard length, SL), but only 35% of the adult diet (200 to 390 mm SL), and <20% of large adult diet (360 to 500 mm SL, which were obtained from spearfishing competitions). Adult and large adult fish consume significantly greater proportions of brachyurans, molluscs and echinoderms than juveniles. Juveniles occur over turfing algae in the upper sub-tidal region to depths of five metres, and feed continuously throughout the day, with bite rates of up to 16 per minute and high gut fullness (60-100%) throughout the day. Conversely, adults occur in deeper sub-tidal habitats (between five and 18 metres), rarely feed during the day (<4 bites per minute) and adult gut fullness declines from >50% in the early morning to <18% by early afternoon. Ontogenetic and diel factors as well as habitat choice influence the diet of this cheilodactylid. The crepuscular nature of feeding in adults of this species is in contrast to several other cheilodactylids which feed during the day.
... Fish >16 cm fork length occupy diel home ranges of 1865 ± 268 m 2 , which approximately doubles during night-time feeding activities (3639 ± 416 m 2 ). Red morwong also demonstrate homing behaviour, travelling 200-900 m and crossing sandy habitat to return to their point of capture Lockett and Suthers, 1998;Lowry and Cappo, 1999;Lowry and Suthers, 2004) Labridae Achoerodus viridis (eastern blue groper) ...
... Similar trends for higher densities of C. fuscus inside MPAs have been reported within the Jervis Bay and Batemans Bay Marine Parks in southern NSW (Barrett et al., 2006;Coleman et al., in preparation;Edgar and Barrett, 2012), and for a related species, Cheilodactylus spectabilis, in a MPA in New Zealand (Cole et al., 1990). The apparent response of C. fuscus to partial protection was consistent with tagging studies which show that the day time movements of C. fuscus (1865 ± 268 m 2 ) which inhabit the central region of the MPA are likely to be contained within MPA boundaries thereby reducing exposure of local aggregations to harvesting pressure Lockett and Suthers, 1998;Lowry, 2003). Protection over spatial scales of average day time movements appears adequate for reducing exposure of local aggregations of C. fuscus to harvesting pressure, despite significantly greater nocturnal movements (3639 ± 416 m 2 ) related to feeding activities (Lowry and Suthers, 1998). ...
... Cheilodactylus fuscus is a dominant part of the spearfishing catch in this region, and is rarely taken by anglers . The species is relatively easy to locate and spear due to its small home range, homing behaviour over distances up to 900 m, diver-neutral and docile behaviour and tendency to aggregate in relatively shallow water Lockett and Suthers, 1998;Lowry, 2003); traits which in combination with its restricted geographical distribution and thus sensitivity to climate change has led to its 'vulnerable' classification (Syms, 2011). Our results supports global research that shows spearing can significantly impact local densities, size, and depth distributions of targeted species (Godoy et al., 2010;Harmelin et al., 1995;Jouvenel and Pollard, 2001) and contributes to the currently limited empirical data suggesting localised effects of recreational spearfishing on cheilodactylids and sparids in marine temperate systems in the southern hemisphere. ...
... Red morwong are benthic carnivores that forage over reef and unconsolidated habitats feeding on a wide variety of prey including amphipods, polychaetes, crabs, molluscs and echinoderms (Bell 1979;Lockett and Suthers 1998). Diet and feeding behaviour are size-specific, with juvenile fish (\200 mm SL) feeding during the day, primarily on amphipods and other small benthic crustaceans. ...
... Diet and feeding behaviour are size-specific, with juvenile fish (\200 mm SL) feeding during the day, primarily on amphipods and other small benthic crustaceans. Larger fish feed primarily at night, on brachyurans, molluscs and echinoderms, with B35 % of their diet being similar to juveniles (Lockett and Suthers 1998). ...
... Fish [16 cm FL of both sexes occupy diel home ranges of 1,865 ± 268 m 2 (mean ± standard error), which approximately doubles during night-time feeding activities (3,639 ± 416 m 2 ) (Lowry and Suthers 1998). Red morwong also demonstrate homing behaviour, travelling 200-900 m and crossing sandy habitat to return to their point of capture (Lockett and Suthers 1998). ...
Knowledge of the population biology, life-history ecology and scales of pre and post-settlement movement of marine species are needed to inform effective conservation management strategies, particularly when spatial information is required for management purposes such as zoning in Marine Protected Areas. This review provides the most current summary from primary and grey literature on the biology and ecology of several coastal fishes of economic and ecological significance in south-east Australia; identifies key knowledge gaps which may impede the development of effective spatial management; and recommends future research directions and methods. Reviewed species are luderick (Girella tricuspidata), eastern rock blackfish (Girella elevata), yellowfin bream (Acanthopagrus australis), tarwhine (Rhabdosargus sarba), snapper (Pagrus auratus), red morwong (Cheilodactylus fuscus) and eastern blue grouper (Achoerodus viridis). The species have a diverse range of life-histories and population traits, and selected parameters were well studied in several species, such as growth (blue groper, luderick, yellowfin bream, tarwhine, snapper), post-settlement movement (red morwong), and larval ecology (yellowfin bream). However, empirical data on levels of pre- and post-settlement connectivity and real-time movements are not available for most species, and this represents a significant gap for improved spatial management. A multidisciplinary approach incorporating a range of methods including acoustic tracking and telemetry, otolith chemistry, intergenerational markers, and biophysical modelling will provide a more comprehensive understanding of life history parameters, movement and connectivity at scales relevant to MPA planning and monitoring.
... A consequence of larger prey can be an increase in energy intake, growth rates and decreased predation risk (Grossman et al. 1980). Such changes have been documented for many invertebrate feeders, including the bay goby (Lepidogobius lepidus; Grossman et al. 1980), red morwong (Cheilodactylus fuscus ; Lockett and Suthers 1998) and lane snapper (Lutjanus synagris; Duarte and Garcia 1999). ...
... Such changes have been demonstrated for planktivorous pempherids, Pempheris affinis, P. multiradiata and P. adspersa (Mooi 2000; Annese and Kingsford 2005), and a benthic feeding cheilodactylid (C. fuscus; Lockett and Suthers 1998). Proposed advantages of size-related changes include decreased competition, increased nocturnal prey availability and avoidance of visual predators by larger adults (Hobson 1973; Helfman 1978). ...
The neon damsel, Pomacentrus coelestis, is characteristic of surge zones on Australian coral reefs and is most abundant on outer slopes of reefs in the southern Great Barrier Reef. When settling, it appears to 'avoid' lagoonal habitats. Recruitment records confirm that this is a general pattern regardless of whether lagoons have permanent or temporary connections to the ocean. This study included direct sampling, around One Tree Reef from the southern Great Barrier Reef, of all presettlement stages of P. coelestis with the aid of light-traps, channel nets and a plankton purse seine. Pelagic juveniles were abundant in catches from light-traps moored outside of the reef crest. In contrast, this developmental stage was rare in catches from all gear types used within the lagoon. The channel nets collected newly hatched larvae that entered the lagoon at night, but either they did not remain in the lagoon or they did not survive because they were not taken from the lagoon by diurnal purse seines. This direct evidence shows that broad-scale habitat selection can begin in the planktonic stage. It implies that pelagic juveniles have excellent sensory and motor capabilities, which disqualify them from being classified and modelled as plankton. Temperature records from inside and outside of the lagoon indicated that warm plumes (up to 3ºC above ambient) influence reef waters near One Tree Reef, and temperature may be one of the cues that presettlement fish use to identify lagoonal habitats.
... In particular, knowledge about activity patterns is much lower in circalittoral and small, cryptobenthic fishes, which may be due to methodological difficulties associated with studying behavioural patterns of such species. Secondly, besides the general lack of information on adult activities other than feeding for most species, there is also very scarce knowledge of diel patterns of larval and juvenile stages, which may differ considerably from adults through ontogenetic shifts in diel feeding activity (Helfman 1978;Lockett and Suthers 1998;Annese and Kingsford 2005;Nunn et al. 2012). Finally, even in adults, the activity patterns can be complex and dependent on various factors. ...
Diel activity patterns are an important aspect of behavioural ecology, yet summarising works on diel activity patterns of fishes are lacking for several regions of the world, including the Mediterranean Sea. Based on a comprehensive review of literature, internet searches, citizen science and personal observations, we compile existing knowledge of diel activity of Mediterranean pelagic and demersal teleosts commonly occurring at depths shallower than 200 m as adults (393 native and 165 newcomer species, representing 124 families), using the categories strictly or mainly diurnal and nocturnal, crepuscular, cathemeral and diel vertical migration. Most of the available data refer to foraging activity patterns of adult fishes, while knowledge of time of reproduction, migratory movements, or territorial defence remains unknown for more than half of the species. Confamilial species often have the same activity pattern, although a high plasticity or diversity in diel activity patterns is seen in some families (Belonidae, Carangidae, Clupeidae, Gadidae, Gobiidae, Scombridae, Scorpaenidae, Sparidae, and Triglidae). We found correlations between adult feeding activity patterns and trophic level, habitat use and depth range: diurnal species have a lower trophic level, prefer shallower depths, and tend to occur over hard bottoms or have multi-habitat use, nocturnal species are mostly carnivorous and prefer soft bottoms in deeper waters, while cathemeral species are commonly carnivorous and pelagic. Our results do not support the hypothesis that nocturnal Indo-Pacific immigrants are more successful colonizers. The present work highlights the perils of over-generalizing activity patterns and shows that several gaps in knowledge of diel activity patterns of fishes remain despite that such knowledge can support conservation efforts.
... Such changes have been demonstrated for planktivorous pempherids, Pempheris affinis, P. multiradiata and P. adspersa (Mooi 2000; Annese and Kingsford 2005), and a benthic feeding cheilodactylid (C. fuscus; Lockett and Suthers 1998). Proposed advantages of size-related changes include decreased competition, increased nocturnal prey availability and avoidance of visual predators by larger adults (Hobson 1973; Helfman 1978). ...
Nemipterids are ubiquitous mid-sized fishes on Indo-Pacific reefs. We investigated the trophic ecology of the nemipterid species Scolopsis bilineatus at two locations on the Great Barrier Reef: One Tree Island and Orpheus Island. Fish ate a variety of benthic invertebrate taxa represented by rank: polychaetes, ophuiroids, sipunculids, nemerteans and small crustaceans. Polychaetes dominated the diet of fish of all sizes. Feeding behaviour and habitat utilization varied with the size of fish. Juveniles fed diurnally and adults nocturnally. Most juveniles fed rapidly in sand and rubble habitat during the day. In contrast, adults occupied shelter sites during the day, but dispersed onto sand to feed at night. A manipulative experiment demonstrated that small adult S. bilineatus exhibit opportunistic behaviour by responding to disturbance of the substratum for the purposes of feeding. Diurnal opportunistic feeding probably has a minimal influence on overall dietary intake. Identification of nocturnal feeding for adult S. bilineatus is of significant ecological importance, as nocturnal fishes often play unique and important roles in energy and nutrient cycling on reefs.
... Juveniles are diurnal feeders, and during the day they inhabit sand and rubble, where they feed (Boaden & Kingsford, 2012). Juveniles of nocturnal species often occupy distinct microhabitats compared with adults, as has been shown for pomadasyids (Ogden & Ehrlich, 1977), apogonids (Lecchini & Galzin, 2005) and the red morwong Cheilodactylus fuscus Castelnau 1879 (Lockett & Suthers, 1998). Juveniles and adults may also differ in the physiology of the eye, and physiological changes such as alteration of the ratio of rods to cones may occur in accordance with a change to nocturnal feeding (Pankhurst, 1989). ...
This study focussed on the demography and ecology of Scolopsis bilineatus at three locations on the Great Barrier Reef: the Lizard Island Group, Orpheus Island and One Tree Island. Scolopsis bilineatus lived for up to 16 years and had four distinct life-history stages, which varied in their distribution patterns, habitat use and reproductive behaviour. Pre-maturational sex change occurred whereby all males were derived from immature females, and males grew faster and larger than females. Small females and larger males generally formed pairs, which influenced their spatial distributions at small scales. Distributions of S. bilineatus were influenced by depth and exposure within reefs, particularly for juveniles, and most fish were found in shallow, sheltered habitats. Abundance was influenced by benthic cover, and was higher in areas of high coral cover and low where algae were abundant. Habitat associations were stronger at the microhabitat scale, and shelter sites were important for adults. Ontogenetic changes in microhabitat associations were found: juveniles occupied sand and rubble, and adults occupied shelters such as caves and overhangs. Adults showed site fidelity for shelter sites over a period of 4 days and returned to specific shelter sites repeatedly. These findings illustrate the importance of understanding the spatial ecology and habitat use of coral reef fishes, particularly with reference to size-based changes within species.
... The occurrence of larger individuals in deeper water has been observed in a variety of species (Clarke 1977, Choat & Ayling 1987, Macpherson & Duarte 1991. Smaller Cheilodactylus fuscus (< 20 cm) have a significantly different diet than the adults (Lockert & Suthers 1998). Juvenile red morwong feed on invertebrates in the foliose algal turf, which is most abundant in the shallows where it is warm and presumably most productive, while adults move over a wide variety of deeper habitat, feeding mainly at night. ...
Strip transect surveys of the large temperate rocky reef fish Cheilodactylus fuscus revealed size- and sex-structured populations across seasons and 3 conditions of wave exposure, from an estuary to the open coast. Large, mostly male, fish (>30 cm fork length) predominated on the open coast and in deeper water (>10 m), while smaller fish predominated in the more protected estuarine areas and in the subtidal regions (<5 m), particularly during the winter to spring recruitment period. Aggregations of C. fuscus were geographically persistent, varying in their size and sex composition over 2 yr, which suggested an ontogenetic migration from shallow and protected areas to more exposed coastal locations. Reasons defining the location of aggregations were unclear, as multivariate analysis of 29 habitat characteristics of 13 aggregation sites versus 6 similar control sites revealed no significant difference. Fish re-colonised the same location 2 to 4 mo after a summer and a winter experiment removed >70% of the adults by intense spear fishing. Experimental sites were recolonised by >20 cm males and females, and rarely by juveniles, There was no significant difference between the pre- and post-removal estimates of home range of tagged fish at removal sites or in controls.
A simple SCUBA diving survey was used to study the habitat use and coexistence of three species in the family Serranidae with sympatric distribution patterns along the rocky subtidal south of Iquique. Depth and microhabitat were recorded for each sampled individual. Samples were taken at 15 different beaches through SCUBA diving in the deepest areas of the first rocky fringe, herein referred to as the transi-tion zone. The data were analyzed according to depth and frequency of use (microhabitat, habitat) for each species and considering three size classes. Dendograms were created to interpret the similarities in the use of beaches, microhabitat, and habitat. The results showed the species to be independent in their use of the micro-habitat and habitat. The most abundant species was the roving Paralabrax humeralis whose habitat was mostly associated with Lessonia trabeculata. Hemiluthjanus macrophthalmos and Acanthistius pictus are cavity specialists, although their microhabitat use differed according to the size of the cavity: H. macrophthalmos occupied larger caves (> 0.5 m) and A. pictus mostly smaller cavities (
In order to identify any factors regulating larval extrusion, growth rates, and settlement patterns of the rockfish Sebastes inermis, otolith microstructure analysis was conducted for two samples from two distinct but contiguous fishing sites in the southwest coast of Miura Peninsula in central Japan: Sajima Bay and Aburatsubo Bay. Condition indices (RNA: DNA ratio, total proteins, Fulton's K) were also examined for habitat quality assessment. Four monthly extrusion groups were identified by daily age backcalculation. Growth rate during the planktonic period was positively related with the duration of this life stage and with water temperature. Flexible settlement timings of each group suggested an adaptive strategy to variability in environmental conditions: larvae experiencing unfavourable temperature settle earlier at smaller lengths and grow faster after settlement. Clear differences in traits related to planktonic and post-settlement stages between sites imply the utilization of different habitats during early life stages, and suggest that offshore mixing of larvae might not be occurring. Juveniles in Sajima Bay had higher growth and condition indices, showing a higher habitat quality and importance as a nursery of this site.
A variety of fish species undergo an ontogenetic change in prey selectivity, and several potentially interacting factors, including nutrient requirement, microhabitat change, and foraging ability, may account for the occurrence of the shift. Here we examine the foraging ecology and ontogenetic diet shift of a micro-carnivorous goby, Pterogobius elapoides (serpentine goby), dominant component of fish assemblage in shallow rocky areas off the coast in Korea and Japan. Although most other gobies are primarily benthic carnivores, P. elapoides is a semipelagic fish; however, little is known about how those species change their foraging tactics with growth. In our diet analyses, the most common diet was pelagic copepods and benthic amphipods, and diet shift was observed from pelagic to benthic with growth. The ontogenetic diet shift seems to be the result of the preference for energetically more profitable prey in larger-size classes as well as the results of different prey availability due to among-habitat variation in diet. However, differential food preference does not appear to affect individual scope for searching food. Several factors such as predation pressures and interspecific resource partitioning might contribute to the changes in diet observed among size classes, which were included in our ongoing tests.
We counted nocturnal fishes both day and night, and monitored the position of tagged individuals on temperate reefs in New South Wales, Australia. Pempheris affinis and P. multiradiata were the most abundant nocturnal planktivores on Sydneys rocky reefs and showed great differences in diel migration behaviour. Both species were observed in deep shelter sites during the day (5–10m), and most emerged into the water column at night. P. multiradiata was found to undergo extensive vertical and horizontal migrations. In contrast, P. affinis remained within daytime depth strata, with tagged individuals often moving less than 20m at night. Tagged adult P. affinis returned to tagging sites for up to 7weeks, indicating high site fidelity. Dietary analysis demonstrated that small and large pempherids differed in diet and the timing of foraging, suggesting a size-based transition from diurnal to nocturnal foraging. Stratified sampling of planktonic assemblages at different depths during the day and night showed spatial variation in the availability of prey items at different times of the day. Amphipods, the main prey of large fish, were only available during the night, and concentrated in shallow water, whereas decapod larvae, consumed mainly by small fish, were abundant day and night. Large P. affinis also fed on polychaetes, which were never found in the stomachs of P. multiradiata, suggesting that these species may have different prey requirements, or that these polychaetes are only found in deep water where foraging P. affinis were abundant. We found no general model for the Pempheridae. The movements and behaviour of nocturnal fishes varied greatly by species, and this may be due to differences in body size, and/or physiological (e.g. visual ability) and ecological constraints.
Stomach contents of 104 C. fuscus (of 275-415 mm standard length) from rocky reef habitats in the Sydney region were analysed. This species was found to be entirely carnivorous, polychaetes, brachyurans, amphipods, gastropods and bivalves comprising the major food types and dominating the diet throughout the year. However, the relative proportions of these food types in the diet were found to vary considerably on a seasonal basis.
Examination of the stomach contents of 153 predominantly sub-adult (modal standard length c. 40 mm) fortescues, C. australis, collected from an estuarine Posidonia aulstralis seagrass meadow near Sydney showed that these fish were macrophagic carnivores. Crustaceans (mainly grapsid crabs and penaeid and carid shrimps) made up 90% of the diet by estimated volume; other major food types included polychaete worms and gastropod molluscs. Minor food items included seagrass, algae and foraminiferans. This predominantly crustacean diet was found to be generally similar to that of a number of other scorpaenid species. No obvious seasonal differences in diet were detected apart from slight changes in the composition of the crustacean component. The morphology of the alimentary tract of C. australis is of a typical carnivorous type. Fortescues were found to be relatively abundant in the Posidonia habitat, representing, on average, 11 .5 % of the fish community by numbers and occurring at an average density of 1 fish per 14 m2. Sub-adult fortescues appear to be highly dependent on the Posidonia habitat and its invertebrate community as a food source.
The feeding ecology of castaneta (Cheilodactylus bergi) was studied during six research cruises carried
out both in the Argentine-Uruguayan Common Fishing Zone during 1986-87 and at the southern border
of the distribution area of the species during 1988-89. A qualitative and quantitative analysis was made.
The trophic spectrum was analysed by fish size class, season and bathymetric depth.
A trend to euryphagy and trophic opportunism was evident. Castaiieta preyed primarily on
polychaetes and secondarily on crustaceans. This species showed both seasonal and bathymetric
variations in its trophic spectrum. The diet of juveniles was closely related to the pelagic food web
(copepods and euphausids), whereas adults consumed benthic organisms (polychaetes, echinoderms and
gammarid amphipods). Such a trend was more evident among larger fish.
The composition of the diet of a landlocked form of the normally catadromous
stream-dwelling fish Galaxias maculatus from Lake Modewarre in south-western
Victoria was studied using a new method of stomach contents analysis based on the
principle of ranking. The overall diet of this landlocked fish was found to consist
mainly of amphipods, chironomid larvae, and copepods (basic food types), with other
groups of crustaceans (cladocerans and ostracods) and insects (trichopteran and
zygopteran larvae) being of lesser importance (secondary food types), and a few other
incidental food types occurring in only small amounts. The diet of this landlocked form
thus consists mainly of crustaceans, in contrast to that of the stream-dwelling form
which comprises mainly insects. There was a change in the pattern of feeding in the
landlocked fish with growth, the smaller fish eating more of the smaller planktonic and
the larger fish more of the larger littoral-benthic food organisms. Amphipods were the
dominant food type during all seasons except autumn, when copepods were dominant.
Cladocerans were also important when they bloomed in summer, and chironomid adults
when they swarmed in autumn. Selection coefficients indicated that those food types
which were dominant in the diet were actively selected and those that were unimportant
were avoided. This landlocked galaxiid was found to share most of the available food
resources with the other four fish species found in the lake, and can be broadly classified
as a euryphagic carnivore.
Feeding was examined in 1574 tarakihi, Cheilodactylus macropterus (Bloch and Schneider) (Teleostei: Cheilodactylidae). Occurrence, points (bulk), and numbers methods of gut content analysis were used throughout the study. By all three methods of analysis, polychaetes, crustaceans, echinoderms, and molluscs (in that order) generally formed the main food groups. Crustaceans dominated the food of tarakihi <15cm in fork length, and polychaetes were the dominant food group in specimens ≥ 15 cm. Length of specimen, sampling depth and area, geographical region, and time of day affected the occurrence, volume, and numbers of food items in the gut, but sex and season did not. Male tarakiili frequented deeper water than females; this result was significant at the <0.001 level.
Stomach contents of Australian bass, M. novemaculeata, sampled from the Hawkesbury River and Georges River in the Sydney Basin, New South Wales, between November 1977 and January 1982 were analysed by the occurrence and points methods. Stomach fullness was also recorded. A total of 143 aquatic and terrestrial animal taxa were present in the diet, and these were grouped into 19 food types for analysis. M. novemaculeata is a euryphagic carnivore. Season and habitat type had significant effects on composition of the diet. Insects were the most important food type, followed by fish and large crustaceans. A large proportion of the diet of bass was derived from allochthonous sources, mainly during summer, and especially in lotic habitats. Mean stomach fullness was highest in spring and lowest in winter. Young M. novernaculeata (TL 11-47 mm) from the Hawkesbury River estuary fed on far fewer prey taxa (mainly chironomids and copepods) than did adults. Dietary overlap occurs between M. novemaculeata and many other carnivorous freshwater vertebrates in the Sydney Basin. However, persistent competitive clashes are generally avoided, either by differences in microhabitat preference and feeding behaviour or by larger-scale habitat partitioning.
The red morwong, Cheilodactylus fuscus Castelnau (Pisces : Cheilodactylidae), is a conspicuous fish on
the rocky reefs of the eastern Australian coast. Visual determination of the sex of individuals in the field is
necessary to remove sex bias in home-range and associated bioaccumulation studies. A sample of 61 fish
(30-50 cm fork length) was collected from spear-fishing competitions in the Sydney area, and from each
fish 16 morphometric measurements were taken. A multivariate analysis revealed that, in comparison with
females, males are generally larger, with a significantly larger orbit-tubercle - or horn - situated in front
of each eye, a smaller eye diameter and a smaller head length. A discriminant function analysis derived
from these four features correctly identified 87% of an independent sample of 40 fish. Visual appraisal of
fish on the basis of the proportional length of the horns misidentified <10 % of fish >30 cm and <30% of
fish 20-30 cm fork length. The orbit-tubercle in males is between 2% and 4% of the fork length and is
composed of bone. According to this simplified visual technique, red morwong aggregations in the
Sydney region have consistently biased sex ratios.
Habitats including depth, diurnal activity patterns, and diets of the two cheilodactylid fishesCheilodactylus zonatus andC. zebra were studied at Igaya Bay, Miyake-jima, Japan. Both species occurred at nearly equal densities in identical habitats and
depths. They preyed on benthonic organisms from early morning to shortly before sunset, when feeding activities decreased
remarkably and intraspecific social behavior greatly increased. Gut analyses showed a high degree of dietary overlap, but
proportions of food items in their diets differed slightly.C. zonatus was more of a food generalist thanC. zebra, showing a higher niche breadth value.C. zebra tends to feed on epifauna, especially gammaridean amphipods and decapods, whileC. zonatus takes both epifauna and infauna including polychaetes.