Abundance and distribution of South Australia's endemic sea star, Parvulastra parvivipara (Asteroidea: Asterinidae)

2008 ◽  
Vol 59 (3) ◽  
pp. 205 ◽  
Author(s):  
Lana M. Roediger ◽  
Toby F. Bolton
Keyword(s):  
High Tide ◽  
South Australia ◽  
Structural Complexity ◽  
Reproductive Mode ◽  
Wave Exposure ◽  
Tide Pool ◽  
Sea Star ◽  
Sea Stars ◽  
Ecological Variables ◽  
Abundance And Distribution

Parvulastra parvivipara is one of the smallest sea stars. It is restricted to tide pools on seven granite platforms within 200 km of coastline on the Eyre Peninsula of South Australia. This species exhibits intragonadal brooding and cannibalism of offspring, and gives birth to non-dispersive juveniles. Its distribution is variable, with specimens occupying few of the many seemingly similar tide pools at each site at differing densities. The abundance and distribution of P. parvivipara were examined in relation to twelve ecological variables of tide pools at all known mainland sites. An estimate of overall population size was also made. Multiple regression analyses showed that the abundance of P. parvivipara was negatively associated with wave-exposure and positively associated with the structural complexity of tide pools. A multiple logistic regression also indicated that the presence of sea stars (distribution) was more likely in structurally complex tide pools with low wave-exposure. Additionally, increasing elevation of a tide pool relative to the high-tide margin within the intertidal zone reduced the likelihood of finding sea stars. It is suggested that the variable abundance and distribution of P. parvivipara may be driven by broad scale ecological variables (e.g. complexity and wave-exposure), localised population extinctions (within tide pools) and recolonisation of tide pools via transportation of individuals across the rock platforms by wave-energy. It is also suggested that strikingly high abundances of P. parvivipara in some tide pools are likely to result from the reproductive mode of this species where each hermaphroditic individual gives birth to cohorts of up to twenty non-dispersive juveniles.

scholarly journals Sea stars generate downforce to stay attached to surfaces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mark Hermes ◽  
Mitul Luhar
Keyword(s):  
Body Shape ◽  
Control Volume ◽  
Water Channel ◽  
Morphological Plasticity ◽  
The Body ◽  
Sea Star ◽  
Sea Stars ◽  
Hydrodynamic Loads ◽  
Spherical Dome ◽  
Star Models

AbstractIntertidal sea stars often function in environments with extreme hydrodynamic loads that can compromise their ability to remain attached to surfaces. While behavioral responses such as burrowing into sand or sheltering in rock crevices can help minimize hydrodynamic loads, previous work shows that sea stars also alter body shape in response to flow conditions. This morphological plasticity suggests that sea star body shape may play an important hydrodynamic role. In this study, we measured the fluid forces acting on surface-mounted sea star and spherical dome models in water channel tests. All sea star models created downforce, i.e., the fluid pushed the body towards the surface. In contrast, the spherical dome generated lift. We also used Particle Image Velocimetry (PIV) to measure the midplane flow field around the models. Control volume analyses based on the PIV data show that downforce arises because the sea star bodies serve as ramps that divert fluid away from the surface. These observations are further rationalized using force predictions and flow visualizations from numerical simulations. The discovery of downforce generation could explain why sea stars are shaped as they are: the pentaradial geometry aids attachment to surfaces in the presence of high hydrodynamic loads.

?Tethyaster albertensis, a Late Cretaceous (Turonian) sea star from the Cardium Formation, Alberta, Canada

1990 ◽  
Vol 64 (6) ◽  
pp. 1045-1049 ◽  
Author(s):  
Russell L. Hall ◽  
Suzan Moore
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Sea Star ◽  
Sea Stars ◽  
Peace River ◽  
The North ◽  
The Family ◽  
Cardium Formation ◽  
Northern Alberta ◽  
Limited Change

Although many of the surviving lineages of sea stars appeared during an early Mesozoic radiation of the class and have undergone limited change since then, they have left a very poor fossil record, particularly in the Mesozoic of North America (Blake, 1981). This record from the Late Cretaceous of Alberta is made more significant by the fact that it is apparently only the second occurrence of a member of the family Astropectinidae in the Cretaceous of North America; Lophidiaster silentiensis was described by McLearn (1944) from the Lower Cretaceous (Albian) Hasler Formation, from a now-submerged locality on the Peace River in northern Alberta. All previously recorded fossil sea stars from the North American Cretaceous are representatives of the family Goniasteridae.

Trophic importance of a temperate intertidal wetland to resident and itinerant taxa: evidence from multiple stable isotope analyses

2011 ◽  
Vol 62 (1) ◽  
pp. 11 ◽  
Author(s):  
Debashish Mazumder ◽  
Neil Saintilan ◽  
Robert J. Williams ◽  
Ron Szymczak
Keyword(s):  
Organic Material ◽  
High Tide ◽  
Structural Complexity ◽  
Primary Sources ◽  
Estuarine Ecosystem ◽  
Plant Materials ◽  
Crab Larvae ◽  
Sporobolus Virginicus ◽  
Feeding Habitat ◽  
Saltmarsh Wetland

Juveniles of commercially important fish species congregate in shallow vegetated estuarine habitats during high tides. Considerable debate has centred on whether the significance of these habitats lies in their provision of greater feeding opportunities, or shelter from predation afforded by greater structural complexity. We tested the hypothesis that an inundated mangrove and saltmarsh wetland provided feeding opportunities for itinerant species, and that the contribution of wetland primary producers and grazing herbivores could be identified in their diet, using stable isotopes of carbon and nitrogen. Potential sources of dietary carbon included mangrove, saltmarsh, seagrass, seagrass epiphytic material and benthic organic material. Saltmarsh plants (mostly Sporobolus virginicus and Juncus kraussii) and fine benthic organic material appeared to be the primary sources of dietary carbon for the resident grazing herbivores in the wetlands, based on IsoSource mixing models. During high tide, species of itinerant fish enter the mangrove and, when inundated, the saltmarsh, and feed primarily on crab larvae and copepods. Fine benthic organic matter, seagrass epiphyte, and C3 and C4 plant materials also supplement the diet of some fish. The crab larvae therefore provide a significant source of nutrition and an important link between the intertidal wetlands and the adjacent estuarine ecosystem. The carnivorous fish Acanthopagrus australis, at the highest trophic level, hunted within or adjacent to the mangrove–saltmarsh wetland and fed on several lower-order consumers within the wetland. The present study highlights the significance of mangrove and saltmarsh wetlands as a feeding habitat for resident grazers and itinerant nekton.

Behavioral interactions between the actinian Tealia piscivora (Anthozoa: Actiniaria) and the asteroid Dermasterias imbricata

1985 ◽  
Vol 63 (8) ◽  
pp. 1921-1929 ◽  
Author(s):  
Joel Elliott ◽  
James Dalby Jr. ◽  
R. Cohen ◽  
D. M. Ross
Keyword(s):  
Sea Anemone ◽  
Sea Star ◽  
Sea Stars ◽  
Behavioral Interactions ◽  
Size Dependent ◽  
Intermediate Size

Interactions between the sea anemone Tealia piscivora and the sea star Dermasterias imbricata have been studied in the laboratory and in subtidal habitats. Dermasterias causes the release of the pedal disk of smaller T. piscivora. The response is specific. Nineteen other sea stars did not cause release; four other species of Tealia did not respond to Dermasterias. The response is size dependent; unfailing and quick in small T. piscivora, less frequent and slow in those of intermediate size, it did not occur at all in large specimens. Unrestrained T. piscivora generally survived interactions with Dermasterias but when prevented from detaching, most of the small anemones were devoured. Tealia piscivora have been observed to detach and engulf small Dermasterias. Most small anemones were found at greater depths; most large anemones were found at lesser depths where Dermasterias were most abundant. It is suggested that by releasing the pedal disk, small T. piscivora eventually end up in deeper water where there are few Dermasterias and thus the anemones escape predation.

scholarly journals Competitors as accomplices: seaweed competitors hide corals from predatory sea stars

2015 ◽  
Vol 282 (1814) ◽  
pp. 20150714 ◽  
Author(s):  
Cody S. Clements ◽  
Mark E. Hay
Keyword(s):  
Field Experiments ◽  
Coral Cover ◽  
Ecological Communities ◽  
Protective Effects ◽  
Sea Star ◽  
Sea Stars ◽  
Macroalgal Blooms ◽  
Feeding Experiments ◽  
High Preference ◽  
And Function

Indirect biotic effects arising from multispecies interactions can alter the structure and function of ecological communities—often in surprising ways that can vary in direction and magnitude. On Pacific coral reefs, predation by the crown-of-thorns sea star, Acanthaster planci , is associated with broad-scale losses of coral cover and increases of macroalgal cover. Macroalgal blooms increase coral–macroalgal competition and can generate further coral decline. However, using a combination of manipulative field experiments and observations, we demonstrate that macroalgae, such as Sargassum polycystum , produce associational refuges for corals and dramatically reduce their consumption by Acanthaster . Thus, as Acanthaster densities increase, macroalgae can become coral mutualists, despite being competitors that significantly suppress coral growth. Field feeding experiments revealed that the protective effects of macroalgae were strong enough to cause Acanthaster to consume low-preference corals instead of high-preference corals surrounded by macroalgae. This highlights the context-dependent nature of coral–algal interactions when consumers are common. Macroalgal creation of associational refuges from Acanthaster predation may have important implications for the structure, function and resilience of reef communities subject to an increasing number of biotic disturbances.

Protective refuges for seeded juvenile scallops (Placopecten magellanicus) from sea star (Asterias spp.) and crab (Cancer irroratus and Carcinus maenas) predation

2005 ◽  
Vol 62 (8) ◽  
pp. 1766-1781 ◽  
Author(s):  
Melisa C Wong ◽  
Myriam A Barbeau ◽  
Allan W Hennigar ◽  
Shawn MC Robinson
Keyword(s):  
Initial Density ◽  
Carcinus Maenas ◽  
Predation Rate ◽  
Seeding Density ◽  
Alternative Prey ◽  
Sea Star ◽  
Placopecten Magellanicus ◽  
Sea Stars ◽  
Cancer Irroratus ◽  
Mussel Density

We examined two methods to provide refuge for seeded juvenile sea scallops (Placopecten magellanicus) from sea star (Asterias spp.) and crab (Cancer irroratus and Carcinus maenas) predation by considering (i) initial density of seeded scallops and (ii) presence of an alternative prey species (blue mussel (Mytilus edulis)). In the seeding density experiment, underwater plots were seeded with different densities of scallops (1, 6, and 69·m–2). In the alternative prey experiment, plots were seeded with one density of scallops (5·m–2) and different densities of mussels (0, 5, and 30·m–2). Animal densities were monitored over time, and predation rate was estimated using tethered scallops. In the seeding density experiment, scallop density in plots initially seeded with 6 scallops·m–2 decreased at the slowest rate. Estimated predation rate of scallops in all plots tended to increase with prey density. In the alternative prey experiment, mussel density decreased immediately after seeding, while scallop density decreased after approximately 1 week. Estimated predation rate of scallops decreased with increasing mussel density. Also, sea stars aggregated in plots containing scallops and mussels. In both experiments, 17%–58% of seeded scallops were lost to dispersal, and final scallop density was approximately 1·m–2, independent of treatment.

Role of current and prey odour in the displacement behaviour of the sea star Asterias vulgaris

2004 ◽  
Vol 82 (10) ◽  
pp. 1547-1553 ◽  
Author(s):  
David Drolet ◽  
John H Himmelman
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Sea Star ◽  
Sea Stars ◽  
Essential Condition ◽  
Asterias Vulgaris ◽  
Degree Of Orientation ◽  
Slow Moving ◽  
Odour Plumes

We performed a factorial experiment to investigate the effects of current and prey odours (mussels) on the displacement behaviour of the sea star Asterias vulgaris (Verrill, 1866). This sea star is a common subtidal predator of sessile and slow-moving animals in the western North Atlantic Ocean. In the presence of current and prey odours in a flume, sea stars oriented themselves upstream and 70% succeeded in finding the prey. Also, the degree of orientation toward the prey increased as the sea star approached the prey. In contrast, only 5% of individuals tested in still water found the prey. Thus, for A. vulgaris the presence of macroscale flow is an essential condition for locating distant prey. Sea stars tested in current alone showed rheotactic behaviour, moving diagonally upstream. This behaviour should enhance the probability of encountering prey odour plumes in the field. Sea stars moved faster and straighter in flowing water than in still water. The slow movement of A. vulgaris in still water probably minimizes costs of foraging when there is a low chance of finding prey and the straight diagonal movement in current should ensure that the sea star continuously samples new areas, rather than resampling the same odour-free area.

scholarly journals Selective Feeding by a Predatory Sea Star Across a Depth Gradient in Northern Patagonia, Chile

2021 ◽  
Vol 8 ◽  
Author(s):  
Ignacio Garrido ◽  
Luis Miguel Pardo ◽  
Ladd E. Johnson ◽  
Dirk Schories
Keyword(s):  
Feeding Behavior ◽  
Prey Selection ◽  
Feeding Strategy ◽  
Benthic Communities ◽  
Generalist Predator ◽  
Subtidal Zone ◽  
Polar Regions ◽  
Depth Gradient ◽  
Sea Star ◽  
Sea Stars

Sea stars often function as keystone predators in food webs of intertidal and subtidal communities, especially in temperate and sub-polar regions. In South America the sea star Cosmasterias lurida is distributed along both the Atlantic and Pacific coasts of Patagonia and is one of the most conspicuous and abundant benthic predators in the shallow subtidal zone (<25 m). Its feeding strategy and prey selection are, however, still poorly known. This study describes the feeding behavior of C. lurida at a site in the Seno del Reloncaví (Chile), assessing its abundance, size and prey selection in the field relative to observed prey abundance and size along a bathymetric gradient. We hypothesized that C. lurida is a generalist predator, feeding on suitable prey according to their availability. However, we found that this predator only consumed a limited number (7 of 48) of potential prey species, primarily the slipper limpets Crepipatella spp. and the mussels Aulacomya ater and Mytilus chilensis. Electivity analysis revealed a clear preference for one mussel (A. ater) but not the other (M. chilensis) as well as depth-dependent selectivity for the slipper limpets, which changed from avoidance to preference with increasing depth. Sea star densities varied with depth, peaking between depths of 5 and 10 m, but the size of sea stars and the size of their prey did not vary significantly along a depth gradient. No significant correlations were found with the most commonly selected prey. These results would indicate that while this predator may be a generalist–opportunist, its feeding behavior is context-dependent and its high selectivity for certain species suggests that this sea star plays a key role structuring subtidal benthic communities in Patagonia.

scholarly journals KEANEKARAGAMAN JENIS BINTANG LAUT DI PANTAI BAHOWO KECAMATAN BUNAKEN KOTA MANADO SULAWESI UTARA

PHARMACON ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 65
Author(s):  
Putri Binambuni ◽  
Marnix Langoy ◽  
Deidy Y Katili
Keyword(s):  
Sampling Method ◽  
Diversity Index ◽  
Wealth Index ◽  
High Water ◽  
Line Transect ◽  
Sea Star ◽  
Sea Stars ◽  
North Sulawesi ◽  
Index Value ◽  
Method Analysis

ABSTRACT Indonesia's territory has high water resources such as fauna diversity. One animal example from the Phylum Echinodermata Class Asteroidea. This is supported by the presence of sand, seagrass and coral reef habitats. Asteroidea is a inhabitant of shallow waters and is commonly found in seagrass beds and coral reefs. This study aims to analyze the diversity of sea star species in Bahowo Beach, Bunaken District, Manado City, North Sulawesi. The sampling method used in this study is the line transect and squared method. Analysis of the data used is Relative Abundance (KR), Diversity Index (H '), Evenness Index (e), and Wealth Index (R). The results of the study found 5 species with a total of 73 individuals. Diversity index value is H '= 1.23 and shows the results of moderate diversity. Keywords: Diversity of Types of Sea Stars in Bahowo Beach, Bunaken District, Manado City, North Sulawesi.  ABSTRAK Wilayah Indonesia memiliki sumber daya perairan yang tinggi seperti keanekaragaman fauna. Salah satu contoh hewan dari Filum Echinodermata Kelas Asteroidea. Hal ini didukung oleh keberadaan habitat pasir, padang lamun, dan terumbu karang. Asteroidea adalah penghuni perairan dangkal dan umumnya terdapat di padang lamun dan terumbu karang. Penelitian ini bertujuan untuk menganalisis keanekaragaman jenis bintang laut yang ada di Pantai Bahowo, Kecamatan Bunaken, Kota Manado, Sulawesi Utara. Metode pengambilan sampel yang diigunakan dalam penelitian ini adalah metode garis transek dan kuadrat. Analisis data yang digunakan yaitu Kelimpahan Relatif (KR), Indeks Keanekaragaman (H’), Indeks Kemerataan (e), dan Indeks Kekayaan (R). Hasil penelitian didapatkan 5 spesies dengan jumlah 73 individu. Nilai indeks keanekaragaman yaitu H’= 1,23 dan menunjukkan hasil keanekaragaman sedang. Kata Kunci: Keanekaragaman Jenis Bintang Laut di Pantai Bahowo, Kecamatan Bunaken, Kota Manado, Sulawesi Utara.

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