Selection of Prey by American Lobsters (Homarus americanus) When Offered a Choice Between Sea Urchins and Crabs

1977 ◽  
Vol 34 (11) ◽  
pp. 2199-2203 ◽  
Author(s):  
Patricia D. Evans ◽  
Kenneth H. Mann
Keyword(s):  
Key Words ◽  
Sea Urchin ◽  
Direct Observation ◽  
Food Preference ◽  
Sea Urchins ◽  
Homarus Americanus ◽  
Cancer Irroratus ◽  
Feeding Experiments ◽  
Selection Of

American lobsters (Homarus americanus) were presented with various numerical combinations of sea urchins (Strongyhcentrotus droebachiensis) and rock crabs (Cancer irroratus) in long-term laboratory feeding experiments. They exhibited a 5:1 preference for crabs when the numerical ratio of urchins to crabs varied from 0.25:1 to 8:1. Lobsters presented with a superabundance of sea urchins (urchin:crab ratios of 16:1 and 100:1) maintained relatively constant proportions of urchins and crabs in their diet. Direct observation indicated that lobsters feed selectively. Their role as key predators in kelp–sea urchin communities is discussed. Key words: food preference, predation, Canadian Atlantic, bioenergetics

Distance Chemoreception and Vision in the Selection of Prey by American Lobster (Homarus americanus)

1978 ◽  
Vol 35 (7) ◽  
pp. 1006-1008 ◽  
Author(s):  
R. W. M. Hirtle ◽  
K. H. Mann
Keyword(s):  
Response Time ◽  
Key Words ◽  
Mytilus Edulis ◽  
Sea Urchins ◽  
Carcinus Maenas ◽  
Homarus Americanus ◽  
Strongylocentrotus Droebachiensis ◽  
American Lobster ◽  
Selection Of

Lobsters responded positively to the waterborne odor of intact living crabs (Carcinus maenas), sea urchins (Strongylocentrotus droebachiensis), and mussels (Mytilus edulis). The frequency of response was higher and the response time shorter to crabs than to sea urchins or mussels. Lobsters also responded to the sight of moving crabs or moving sea urchins, but not to the sight of stationary specimens. Crabs are probably more attractive to lobsters because of their odor and their greater activity, compared with sea urchins or mussels. Key words: lobsters, prey, chemoreception, vision, crabs, sea urchins, movement, odor

Estrogen administration to the edible sea urchin Paracentrotus lividus (Lamarck, 1816)*

Zoosymposia ◽  
2012 ◽  
Vol 7 (1) ◽  
pp. 247-254 ◽  
Author(s):  
SILVIA MERCURIO ◽  
MICHELA SUGNI ◽  
DENISE FERNANDES ◽  
CINTA PORTE ◽  
MARIA DANIELA CANDIA CARNEVALI
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Gonad Index ◽  
Hormonal Treatment ◽  
Paracentrotus Lividus ◽  
Maturation Stage ◽  
Physiological Values ◽  
Estrogen Administration

Despite the extensive use of sea urchins in embryology, the hormonal mechanisms regulating echinoid reproductive pro­cesses are scarcely known. This research is focused on the role of estradiol (E2), whose presence and seasonal variations in different echinoderm tissues have been previously reported. Three different concentrations of E2 were administered (via peristomial injection, 2/week) to adult specimens of the sea urchin Paracentrotus lividus for 2 and 12 weeks. The lowest concentration was close to physiological values, previously measured in field specimens. Despite the increase of circulating E2 in the coelomic fluids, neither short- nor long-term hormonal treatment induced marked variations in the considered reproductive parameters. The Gonad Index appeared to be more influenced by the feed intake than by E2. Similarly, the maturation stage of the gonads was not markedly affected by E2 injection, although some sex-specific dif­ferences could be observed: treated females never reached the maximum maturation stage compared to controls, although this was observed in males injected with the lowest E2 concentration. Although further research is needed to confirm our observations, according to the present study E2 does not markedly influence echinoid reproduction and, particularly, it does not promote female maturation, as reported for vertebrates and suggested for asteroid echinoderms.

Seaweeds, Sea Urchins, and Lobsters: A Reappraisal

1985 ◽  
Vol 42 (12) ◽  
pp. 2061-2072 ◽  
Author(s):  
Robert J. Miller
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Stomach Contents ◽  
Homarus Americanus ◽  
Strongylocentrotus Droebachiensis ◽  
Sea Otter ◽  
Feeding Rates ◽  
Growth And Survival ◽  
Definition Of ◽  
Urchin Grazing

A popular hypothesis, that on the south coast of Nova Scotia the green sea urchin (Strongylocentrotus droebachiensis) has been released from control by predators, is critically reviewed. Predator control is given the functional definition of limiting sea urchin grazing sufficient to permit abundant growth of seaweed. Of the predators identified, the American lobster (Homarus americanus) is the least likely to have been important in sea urchin control in recent decades. Feeding rates, stomach contents, and field biomass are available for this species. A smaller amount of data available for the rock crab (Cancer irroratus) and benthic feeding fish points to the conclusion that they likewise cannot control urchin populations. Among other temperate sea urchin species the case is strongest for sea otter control of Strongylocentrotus sp. in some areas of the west coast of North America. The formation of sea urchin grazing fronts, a usual step in the destruction of seaweed beds, has been explained as a behavioral response to predators. This may in fact be merely a response to the location of food. Evidence for suspected enhancement of lobster production by seaweeds is equivocal, and comparative field data collected in and out of seaweed beds (e.g. lobster abundance, food, growth, and survival) have not been published.

scholarly journals PERAN EKOLOGI BULU BABI DALAM KOMUNITAS RUMPUT LAUT DI PERAIRAN PESISIR KEMA KABUPATEN MINAHASA UTARA

2011 ◽  
Vol 7 (1) ◽  
pp. 1
Author(s):  
Ruddy D Moningkey
Keyword(s):  
Sea Urchin ◽  
Functional Role ◽  
Food Preference ◽  
Negative Impact ◽  
Sea Urchins ◽  
Gut Contents ◽  
Seagrass Bed ◽  
Transect Line ◽  
Feeding Periodicity

A study on the functional role of the sea urchin, Salmacis belli, on seagrass bed near the coast of Kema, North Minahasa Regency, was done by analyzing the gut contents, the food preference, and the feeding periodicity. Sea urchins and plants were collected from the seagrass bed by snorkeling along a 100 M transect line with 30 quadrates randomly placed. The feeding periodicity was determined from the gut index in 24 hours with 3 hour intervals.  The results showed that the sea urchin S. belli fed mainly on seagrass Thallasia hemprichii, Enhalus acoroides and Halimeda opuntioa. The feeding periodicity data indicated that the sea urchins actively fed in the day. The grazing capacity of the sea urchin was not affected by their body size.  In high density, sea urchins could potentially cause negative impact on the seagrass bed (i.e., destruction of the meadow).

scholarly journals Fitness benefits and costs of shelters to the sea urchin Glyptocidaris crenularis

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8886
Author(s):  
Xiaomei Chi ◽  
Jiangnan Sun ◽  
Yushi Yu ◽  
Jia Luo ◽  
Bao Zhao ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Natural Environments ◽  
Trade Off ◽  
Positive Effects ◽  
Long Term Study ◽  
Glyptocidaris Crenularis ◽  
Fitness Benefits ◽  
Benefits And Costs

Understanding the ecological role of shelters is greatly hampered by the scarcity of long-term laboratory experiments on the trade-off between fitness benefits and costs. This lack probably leads to an underestimation of the negative and/or positive effects on behaviors and growth of marine invertebrates in benthic ecosystems. Although our previous study revealed a significant effect on fitness-related traits of Glyptocidaris crenularis after 31 months, the present study extended it and investigated fitness benefits and/or costs of long-term sheltering on sea urchins to over 7 years. The present long-term study suggests that the previously reported reduction in feeding rate probably resulted from a reduction in reflexive feeding motions (Aristotle’s lantern reflex) rather than changes in foraging behavior. Actively seeking sheltering behavior was negatively impacted in individuals with continuous access to shelters. However, covering and righting behaviors did not differ in sheltered sea urchins, indicating that these behaviors are maintained to escape from adverse environments regardless of shelter. Body size of sea urchins in the group with shelters was significantly lower than those without shelters after 7 years. Weights of gonads and gut were not significantly different after 7 years despite previous observations of differences after ~2.5 years. The present study provides valuable information on the trade-off between fitness benefits and costs to sea urchins residing in shelters. However, the present study is only a laboratory investigation for one urchin species (G. crenularis) which does not consider the complexity of natural environments. Field studies should be carried out with G. crenularis and other sea urchin species, before a more universal conclusion can be drawn.

Predation by Rock Crabs (Cancer irroratus) on Diseased Sea Urchins (Strongylocentrotus droebachiensis) in Nova Scotia

1984 ◽  
Vol 41 (12) ◽  
pp. 1847-1851 ◽  
Author(s):  
Robert E. Scheibling
Keyword(s):  
Nova Scotia ◽  
Sea Urchins ◽  
Mass Mortality ◽  
Strongylocentrotus Droebachiensis ◽  
Significant Preference ◽  
Laboratory Findings ◽  
Cancer Irroratus ◽  
Feeding Experiments ◽  
Defensive Behaviors ◽  
Strong Attachment

Predation of morbid sea urchins (Strongylocentrotus droebachiensis) by rock crabs (Cancer irroratus) and other predators was observed using SCUBA during an outbreak of disease in southwestern Nova Scotia in August 1983. Disease increases susceptibility of sea urchins to predation by precluding natural defensive behaviors including spine projection, strong attachment to the substratum, and aggregation. In laboratory feeding experiments, rock crabs preferred diseased or narcotized sea urchins over healthy ones and fed upon them at a much higher rate than crabs given only healthy sea urchins as prey. Rock crabs showed no significant preference between diseased and narcotized sea urchins. Rock crabs clearly preferred mussels over healthy or diseased sea urchins. Although rock crabs do not appear to be important predators of healthy sea urchins, from field and laboratory findings I conclude that they contribute to mass mortality of sea urchins by preying upon morbid individuals during outbreaks of disease.

scholarly journals Attraction to and selection of prey by immature lobsters (Homarus americanus)

1982 ◽  
Vol 60 (3) ◽  
pp. 326-336 ◽  
Author(s):  
J. A. Carter ◽  
D. H. Steele
Keyword(s):  
Sea Urchins ◽  
Homarus Americanus ◽  
Significant Preference ◽  
Relative Attractiveness ◽  
Rock Crab ◽  
Selection Of

This study was concerned with the relative attractiveness of prey extracts and metabolites and ninhydrin-positive compounds (NPCs) offered to immature lobsters (Homarus americanus). Extracts of rock crabs were the most attractive. Those of sea urchins and starfish were the least attractive. Immature lobsters showed significant preference for rock crab extract when offered those of various species. Only rock crab metabolites elicited significant food-searching responses from lobsters. Proline and ammonia were the most attractive of the NPCs tested.Selection of intact prey by immature lobsters was observed. Brittlestars, nereids, and polynoids were attacked more often than other prey, including rock crabs, starfish, mussels, sea urchins, and periwinkles. Polychaetes were almost always completely consumed when attacked. Immature lobsters ate smaller proportions of larger prey. Small rock crabs and large starfish, sea urchins, and mussels tended to avoid predation.An analysis of prey NPCs implicated the higher levels of NPCs, such as proline and ammonia, as a reason for the significant attractiveness of rock crabs.

scholarly journals Ocean warming alters predicted microbiome functionality in a common sea urchin

2018 ◽  
Vol 285 (1881) ◽  
pp. 20180340 ◽  
Author(s):  
Cecilia J. Brothers ◽  
William J. Van Der Pol ◽  
Casey D. Morrow ◽  
Joseph A. Hakim ◽  
Hyunmin Koo ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Seawater Temperature ◽  
Coelomic Fluid ◽  
Lytechinus Variegatus ◽  
Community Function ◽  
Near Future

The microbiome of sea urchins plays a role in maintaining digestive health and innate immunity. Here, we investigated the effects of long-term (90 day) exposure to elevated seawater temperatures on the microbiome of the common, subtropical sea urchin Lytechinus variegatus . The community composition and diversity of microbes varied according to the type of sample collected from the sea urchin (seawater, feed, intestines, coelomic fluid, digested pellet and faeces), with the lowest microbial diversity (predominately the order Campylobacterales) located in the intestinal tissue. Sea urchins exposed to near-future seawater temperatures maintained the community structure and diversity of microbes associated with their tissues. However, marginal, non-significant shifts in microbial community structure with elevated temperature resulted in significant changes in predicted metagenomic functions such as membrane transport and amino acid and carbohydrate metabolism. The predicted changes in key metabolic categories suggest that near-future climate-induced increases in seawater temperature could shift microbial community function and impact sea urchin digestive and immune physiology.

Women's Participation in Politics: Ukrainian Case

2014 ◽  
Vol 2013 (3) ◽  
pp. 53-66
Author(s):  
Skovikov Alexey
Keyword(s):  
Political Culture ◽  
Separation Of Powers ◽  
Party Competition ◽  
Political Life ◽  
Ruling Class ◽  
Political Actors ◽  
Women's Participation ◽  
Democratic Transformation ◽  
Selection Of

AbstractThe international practices takes into account the question of women's participation in the political life of modern Ukraine. The selection of the state was due to the dynamic process of democratic transformation - the separation of powers, the formation of multi-party competition among political actors in the electoral process, the activity women in the various institutions of civil society. The position was claimed on the basis of empirical data range of academic institutions and reputable sociological centers, and also interviews with experts who said that the creation of real conditions for self-realization by women's interest in politics is only possible for long term. The process is controversial and caused by political culture, traditions and interests of the ruling class represented mainly by men.

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