Hiding time of the hermit crab Calcinus californiensis: observations from different shell types

2015 ◽  
Vol 93 (7) ◽  
pp. 559-565 ◽  
Author(s):  
Carlos Enrique Chávez-Solís ◽  
Guillermina Alcaraz
Keyword(s):  
Water Column ◽  
Potential Risk ◽  
Hermit Crab ◽  
Hermit Crabs ◽  
Resource Value ◽  
Risk Of Predation ◽  
Potential Risks ◽  
Time Required ◽  
The Cost ◽  
Return To Activity

Hermit crabs respond to predators by hiding in their shells. However, retraction may cause the crab to lose hold of the rock and fall through the water column, and the crab may land with the shell aperture in a different orientation. When the shell is aperture down, hermit crabs return to activity by moving their bodies forward and placing their legs on the ground. In contrast, when the shell is aperture up, crabs need to perform a righting maneuver by extending part of their bodies out of the shell, which makes them more vulnerable to predation. The main goal of this study was to examine the hiding time of the hermit crab Calcinus californiensis Bouvier, 1898 in different shell species under these two different situations to better understand the conflict between the cost of staying in hiding and the risk of predation. The study was conducted in rocky tide pools using seven different shell types that reflect different predator protection and resource value to the crab (based on previous studies). We measured the time required to perform the righting maneuver as a measure of the potential risk incurred when returning to activity. The hiding time with the shell aperture down was not affected by shell species. The requirement to carry out a righting maneuver lengthened the hiding time, which varied in the different shell species according to the time required to recover the natural position. The potential risks associated with the righting time, the protection offered by the shells, and the resource value played an important role in the hiding time of the crabs using different shells. This study shows that hermit crabs are aware of the attributes of the shell and use this information to make decisions about how long to stay hidden after being threatened.

scholarly journals Pengembangan Sistem Manajemen Risiko di Badan Perencanaan Pembangunan Daerah (BAPPEDA) Kota Bontang berdasarkan Kerangka ISO 31000

2017 ◽  
Vol 1 (1) ◽  
pp. 11
Author(s):  
Wijdani Anindya Hadi ◽  
Putu Dana Karningsih
Keyword(s):  
Risk Management ◽  
Potential Risk ◽  
Delphi Method ◽  
Controlling System ◽  
Iso 31000 ◽  
Potential Risks ◽  
The Cost ◽  
Evacuation Route ◽  
Very High ◽  
Made In

Procurement is one of activity of government institution. ULP Bontang as a procurement unit is a part of Bappeda Bontang. Due to importance of procurement process, ULP Bontang needs to manage its risks by identifying, analyzing and controlling potential risk that may impedes ULP objectives. All goverment institution refer to a Internal Government Controlling System which called by Sistem Pengendalian Intern Pemerintah (SPIP) for conducting its risk management.  Since there are several part of SPIP is not applicable in ULP Bontang. Therefore in this research, SPIP is modified based on ISO 31000 framework. Moreover, Delphi method is utilized to identiry riks  involving five experts and established 23 potential risk in ULP Bontang. The modifications were also made in developing of severity and probability tables corresponding to the conditions of ULP Bontang. The formulation of mitigation recommendation concerned by very high potential risks. The mitigation for risk number (12) ULP Bontang office is not representative are securing ULP office using fingerprint device so only authorized personel allowed to enter the office. The cost required for this mitigation is about Rp 30.000.000 and Rp 32.000.000 for CCTV installation and evacuation route sign and also ULP needs to partnership with other institution to securing ULP Bontang member.Keyword : risk management, procurement, ISO 31000, Delphi Method, ULP Bontang

Use of cold tolerant eucalyptus species as a partial replacement for southern mixed hardwoods

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 29-35 ◽  
Author(s):  
PETER W. HART ◽  
DALE E. NUTTER
Keyword(s):  
Potential Method ◽  
The United States ◽  
Partial Replacement ◽  
Growth Time ◽  
Eucalyptus Species ◽  
Cold Tolerant ◽  
Hardwood Pulp ◽  
Time Required ◽  
The Cost ◽  
Operational Data

During the last several years, the increasing cost and decreasing availability of mixed southern hardwoods have resulted in financial and production difficulties for southern U.S. mills that use a significant percentage of hardwood kraft pulp. Traditionally, in the United States, hardwoods are not plantation grown because of the growth time required to produce a quality tree suitable for pulping. One potential method of mitigating the cost and supply issues associated with the use of native hardwoods is to grow eucalyptus in plantations for the sole purpose of producing hardwood pulp. However, most of the eucalyptus species used in pulping elsewhere in the world are not capable of surviving in the southern U.S. climate. This study examines the potential of seven different cold-tolerant eucalyptus species to be used as replacements for, or supplements to, mixed southern hardwoods. The laboratory pulping and bleaching aspects of these seven species are discussed, along with pertinent mill operational data. Selected mill trial data also are reviewed.

Sample sizes for point, double sampling

1992 ◽  
Vol 22 (7) ◽  
pp. 980-983 ◽  
Author(s):  
Richard G. Oderwald ◽  
Elizabeth Jones
Keyword(s):  
Basal Area ◽  
Double Sampling ◽  
Sample Sizes ◽  
Measuring Volume ◽  
Sample Points ◽  
Time Required ◽  
The Cost ◽  
Minimum Ratio

Formulas are derived for determining the total number of sample points and the number of volume points for a point, double sample with a ratio of means estimator to replace a point sample and achieve the same variance. A minimum ratio of the cost of measuring volume to the cost of measuring basal area at a point is determined for which the point, double sample will be less costly, in terms of time required to measure points, than the point sample.

Metopelloides paguri sp. nov., a new species of symbiotic stenothoid amphipod (Crustacea: Amphipoda: Stenothoidae) associated with sublittoral hermit crabs from the Russian coasts of the Sea of Japan

Zootaxa ◽  
2012 ◽  
Vol 3244 (1) ◽  
pp. 59 ◽  
Author(s):  
IVAN MARIN ◽  
SERGEY SINELNIKOV
Keyword(s):  
New Species ◽  
Sea Of Japan ◽  
Hermit Crab ◽  
Hermit Crabs ◽  
The Sea Of Japan ◽  
Crab Species ◽  
Body Coloration ◽  
The Family ◽  
Mandibular Palp ◽  
A New Species

A new species of amphipod from the genus Metopelloides Gurjanova, 1938 (Crustacea: Amphipoda: Stenothoidae) asso-ciated with two species of sublittoral hermit crab species, Pagurus pectinatus (Stimpson, 1858) and Elassochirus cavi-manus (Miers, 1879) (Crustacea: Decapoda: Paguridae), is described from the Russian coasts of the Sea of Japan. The newspecies clearly differs from the congeners by the combination of morphological features such as telson without lateralspines, an elongated mandibular palp with single apical setae, the structures of distoventral palmar margins of subchelaon gnathopods I and II in females, bright white-red body coloration. Thus, the record of Metopelloides paguri sp. nov.represents the second record of the family Stenothoidae in the association with sublittoral hermit crabs from the Sea of Japan.

scholarly journals Larval Gnathostomes and Spargana in Chinese Edible Frogs, Hoplobatrachus rugulosus, from Myanmar: Potential Risk of Human Infection

2020 ◽  
Vol 58 (4) ◽  
pp. 467-473
Author(s):  
Jong-Yil Chai ◽  
Bong-Kwang Jung ◽  
Jin-Youp Ryu ◽  
Hyun-Seung Kim ◽  
Sung-Jong Hong ◽  
...  
Keyword(s):  
Potential Risk ◽  
Human Infection ◽  
Local Market ◽  
Digestion Method ◽  
Artificial Digestion ◽  
Potential Risks ◽  
The Mean

Chinese edible frogs, Hoplobatrachus rugulosus, were examined to estimate the potential risks of human gnathostomiasis and sparganosis in Myanmar. A total of 20 frogs were purchased in a local market of Yangon and examined with naked eyes and the artificial digestion method after skin peeling in June 2018 and June 2019. Larvae of gnathostomes and Spirometra (=spargana) were detected in 15 (75.0%) and 15 (75.0%) frogs with average intensities of 10.5 and 6.3 larvae per infected frog, respectively. Gnathostome larvae were 2.75-3.80 (av. 3.30) mm long and 0.29-0.36 (0.33) mm wide. They had a characteristic head bulb with 4 rows of hooklets, a muscular long esophagus, and 2 pairs of cervical sac. The mean number of hooklets were 41, 44, 47, and 50 on the 1st, 2nd, 3rd, and 4th row, respectively. Collected spargana were actively moving, particularly with the scolex part, and have ivory-white color and variable in size. Conclusively, it has been first confirmed that Chinese edible frogs, H. rugulosus, are highly infected with larval gnathostomes and spargana in this study. Consuming these frogs is considered a potential risk of human gnathostomiasis and sparganosis in Myanmar.

scholarly journals A Short Path Quantum Algorithm for Exact Optimization

Quantum ◽  
2018 ◽  
Vol 2 ◽  
pp. 78 ◽  
Author(s):  
M. B. Hastings
Keyword(s):  
Hybrid Algorithm ◽  
Optimal Solution ◽  
Quantum Algorithm ◽  
Low Energy ◽  
Weighted Sum ◽  
Natural Hybrid ◽  
Sum Of Products ◽  
Time Required ◽  
The Cost ◽  
Exact Optimization

We give a quantum algorithm to exactly solve certain problems in combinatorial optimization, including weighted MAX-2-SAT as well as problems where the objective function is a weighted sum of products of Ising variables, all terms of the same degree D; this problem is called weighted MAX-ED-LIN2. We require that the optimal solution be unique for odd D and doubly degenerate for even D; however, we expect that the algorithm still works without this condition and we show how to reduce to the case without this assumption at the cost of an additional overhead. While the time required is still exponential, the algorithm provably outperforms Grover's algorithm assuming a mild condition on the number of low energy states of the target Hamiltonian. The detailed analysis of the runtime dependence on a tradeoff between the number of such states and algorithm speed: fewer such states allows a greater speedup. This leads to a natural hybrid algorithm that finds either an exact or approximate solution.

Rich-Media Interactive Simulations

2016 ◽  
pp. 261-283
Author(s):  
Suzanne Tsacoumis
Keyword(s):  
Real World ◽  
High Fidelity ◽  
Rich Media ◽  
Job Candidates ◽  
Real World Applications ◽  
Fidelity Measures ◽  
Time Required ◽  
The Cost ◽  
Interactive Simulations

High fidelity measures have proven to be powerful tools for measuring a broad range of competencies and their validity is well documented. However, their high-touch nature is often a deterrent to their use due to the cost and time required to develop and implement them. In addition, given the increased reliance on technology to screen and evaluate job candidates, organizations are continuing to search for more efficient ways to gather the information they need about one's capabilities. This chapter describes how innovative, interactive rich-media simulations that incorporate branching technology have been used in several real-world applications. The main focus is on describing the nature of these assessments and highlighting potential solutions to the unique measurement challenges associated with these types of assessments.

Coenobichnus currani (new ichnogenus and ichnospecies): Fossil trackway of a land hermit crab, early Holocene, San Salvador, Bahamas

2003 ◽  
Vol 77 (3) ◽  
pp. 576-582 ◽  
Author(s):  
Sally E. Walker ◽  
Steven M. Holland ◽  
Lisa Gardiner
Keyword(s):  
Hermit Crab ◽  
Fossil Record ◽  
Trace Fossil ◽  
Early Holocene ◽  
Hermit Crabs ◽  
Coastal Environments ◽  
Atlantic Region ◽  
Western Atlantic ◽  
San Salvador ◽  
Left And Right

Land hermit crabs (Coenobitidae) are widespread and abundant in Recent tropical and subtropical coastal environments, yet little is known about their fossil record. A walking trace, attributed to a land hermit crab, is described herein as Coenobichnus currani (new ichnogenus and ichnospecies). This trace fossil occurs in an early Holocene eolianite deposit on the island of San Salvador, Bahamas. The fossil trackway retains the distinctive right and left asymmetry and interior drag trace that are diagnostic of modern land hermit crab walking traces. The overall size, dimensions and shape of the fossil trackway are similar to those produced by the modem land hermit crab, Coenobita clypeatus, which occurs in the tropical western Atlantic region. The trackway was compared to other arthropod traces, but it was found to be distinct among the arthropod traces described from dune or other environments. The new ichnogenus Coenobichnus is proposed to accommodate the asymmetry of the trackway demarcated by left and right tracks. The new ichnospecies Coenobichnus currani is proposed to accommodate the form of the proposed Coenobichnus that has a shell drag trace.

Hermit Crabs as Emergent Icons of Global Waste Epidemic and Their Unreal Estate Housing Struggles

2019 ◽  
Vol 27 (7) ◽  
pp. 697-715
Author(s):  
Concepción Cortés Zulueta
Keyword(s):  
Hermit Crab ◽  
Polar Bear ◽  
Companion Animals ◽  
Hermit Crabs ◽  
Wild Animals ◽  
Housing Crisis ◽  
Glass Bottle ◽  
Human Waste

AbstractA hermit crab housed in a broken glass bottle or inside a plastic cap is becoming like a polar bear stranded on a tiny, melting iceberg: those pictures are emergent icons of the plight faced by oceans and creatures, caused by human waste excesses and wrongdoings. These inventive crustaceans fulfill a warning role akin to charismatic megafauna, and induce empathy with varied sources, dominated by human projections like the housing crisis metaphor. Crabs emerge like a cluster where many opposed notions collapse, while they stage the frictions of a complex, fractured balance. They are wild animals, and controversial companion animals, and when they live inside human trash, they show resilience that questions the natural-artificial divide. Simultaneously, they remind humans of strains imposed upon them, the oceans, and the planet, becoming tokens of the unbalances with which humans have to deal in their often-misguided attempts to fix the things they are rupturing.

scholarly journals Microplastics disrupt hermit crab shell selection

2020 ◽  
Vol 16 (4) ◽  
pp. 20200030 ◽  
Author(s):  
Andrew Crump ◽  
Charlotte Mullens ◽  
Emily J. Bethell ◽  
Eoghan M. Cunningham ◽  
Gareth Arnott
Keyword(s):  
Hermit Crab ◽  
Information Gathering ◽  
Animal Behaviour ◽  
Hermit Crabs ◽  
Marine Biodiversity ◽  
Crab Shell ◽  
Potential Threat ◽  
Pagurus Bernhardus

Microplastics (plastics < 5 mm) are a potential threat to marine biodiversity. However, the effects of microplastic pollution on animal behaviour and cognition are poorly understood. We used shell selection in common European hermit crabs ( Pagurus bernhardus ) as a model to test whether microplastic exposure impacts the essential survival behaviours of contacting, investigating and entering an optimal shell. We kept 64 female hermit crabs in tanks containing either polyethylene spheres ( n = 35) or no plastic ( n = 29) for 5 days. We then transferred subjects into suboptimal shells and placed them in an observation tank with an optimal alternative shell. Plastic-exposed hermit crabs showed impaired shell selection: they were less likely than controls to contact optimal shells or enter them. They also took longer to contact and enter the optimal shell. Plastic exposure did not affect time spent investigating the optimal shell. These results indicate that microplastics impair cognition (information-gathering and processing), disrupting an essential survival behaviour in hermit crabs.

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