Filtering out parasites: sand crabs (Lepidopa benedicti) are infected by more parasites than sympatric mole crabs (Emerita benedicti (original) (raw)
Related papers
Nematodes Infect, But Do Not Manipulate Digging By, Sand Crabs, Lepidopa benedicti
Integrative and Comparative Biology, 2014
We examined sand crabs (Lepidopa benedicti) for endoparasites, and found the only parasite consistently infecting the studied population were small nematodes. Because many nematodes have complex life cycles involving multiple hosts, often strongly manipulating their hosts, we hypothesized that nematodes alter the behavior of their sand crab hosts. We predicted that more heavily infected crabs would spend more time above sand than less heavily infected crabs. Our data indicate infection by nematodes was not correlated with duration of time crabs spent above sand. We also suggest that organisms living in sandy beaches may benefit from relatively low parasite loads due to the low diversity of species in the habitat.
Parasite infection and sand coarseness increase sand crab (Emerita analoga) burrowing time
Behavioural Processes, 2011
Parasites with indirect life cycles require trophic transmission from intermediate hosts to definitive (vertebrate) hosts. Transmission may be facilitated if parasite infection alters the behavior of intermediate hosts such that they are more vulnerable to predation. Vulnerability to predation may also be influenced by abiotic factors; however, rarely are the effects of parasites and abiotic factors examined simultaneously. The swash zone of sandy beaches is a particularly harsh environment. Sand crabs (Emerita analoga) burrow rapidly in the swash zone to avoid predators and dislodgment. We examined prevalence and abundance of the acanthocephalan parasite Profilicollis altmani in sand crabs, and investigated the synergistic effects of sand grain size (an important abiotic factor), parasite infection, body size and reproductive condition on burrowing speed in females, from three California sites. More heavily parasitized crabs burrowed more slowly, making them potentially more vulnerable to predation by marine bird definitive hosts. Ovigerous females harbored more parasites than non-ovigerous females, but burrowed more quickly. All crabs burrowed slowest in the coarsest sand, and burrowing times increased with repeated testing, suggesting that it is energetically costly. Abiotic and biotic factors influence burrowing, and behavioral variation across sites may reflect the response to natural variation in these factors.
Journal of Parasitology, 2011
Larval tapeworms (Polypocephalus sp.) reside within the central nervous system of decapod crustaceans. Living within the nervous system would seem to create an excellent opportunity for the parasites to manipulate the behavior of their hosts, so we tested the hypothesis that behavior of white shrimp (Litopenaeus setiferus) would be correlated with the level of parasitic infection. We videorecorded the behavior of L. setiferus for 8 hr, then examined the nervous system and digestive glands for parasite infection. Larval Polypocephalus sp. were found in the nerve cord, often in large numbers, but only very rarely in the digestive gland, which was typically infected by the larval stage of the nematode, Hysterothylacium sp. There were significantly more Polypocephalus larvae in the abdominal and thoracic ganglia than the subesophageal ganglia and brain. Walking, but not swimming, was significantly and positively related to the number of Polypocephalus sp. lodged in nervous tissue, as well as shrimp carapace length. Polypocephalus sp. is 1 of only a few parasites residing inside the host nervous system and it may, therefore, be suitable for investigating mechanisms of parasite manipulation of invertebrate host behavior.
Open Journal of Marine Science, 2015
The species composition and infection levels were determined for helminth parasites in the mole crab, Emerita rathbunae, collected from seven sandy beaches from Guerrero and Michoacán, México. A total of 494 crabs were collected between August and December of 2009. The number of crabs that were examined from each beach varied from 40 in Lázaro Cárdenas to 114 in El Revolcadero. The cephalothorax length varied significantly between the sampled beaches, from 32.9 ± 5.5 mm (Ixtapa) to 40.5 ± 1.7 mm (Las Trancas). Four species of larval parasites were identified: 1 metacercaria (Microphallus nicolli), 1 cystacanth (Profilicollis sp.), 1 cestode (Trypanorhyncha) and 1 nematode (Proleptus sp.). Infection levels (prevalence and mean abundance) varied significantly between beaches, due to possible differences in the availability of final or intermediate hosts in beaches visited by tourist and those beaches not visited by tourists, as well as the size of individual hosts. Helminth communities, at levels of component and infracommunity, were characterized by a low number of species (3 to 4) and a high dominance by the metacercaria of M. nicolli. The body size of the hosts was positively correlated with the number of parasites and species richness of helminths, indicating that larger crabs accumulate a higher number of parasites during the lifetime, and that they harbor a higher number of species of helminth than smaller crabs.
Zoosystematics and Evolution, 2016
Parasites, by definition, can affect mortality of their host, making parasitism an important biotic determinant of animal population dynamics and community structure. Reduction in the number of larger, reproductive age females in populations of the Pacific sand crab, Emerita rathbunae (Decapoda, Hippidae), was observed in studies of the helminth community of this host. The aim of this study was to determine if high abundance of the metacercaria of the trematode, Microphallus nicolli (Microphallidae), causes mortality in this host. Females of E. rathbunae were collected from four sandy beaches in Guerrero State, Mexico, and helminths were collected from each crab. An analysis of variance (Anova) was applied to these data in order to identify differences in abundance between sizes of crabs, and an analysis of covariance (Ancova) was applied to identify differences in the abundance of metacercariae between locations. Parasite-related mortality was inferred by a decrease in abundance in older hosts. Linear and polynomial regressions of mean abundance of helminths (log x+1 transformed data) vs. cephalothorax length of crabs were significant for the four populations of E. rathbunae, indicating increased mortality of older, more heavily infected female crabs and resultant removal from the population. Encapsulation and melanization of cysts by crabs was observed, indicating that an immune response by crabs also killed a portion of the cysts from subsequent exposures. Mortality of hosts through behavioral modification favoring transmission of highly infected crabs was suggested as the driving force behind this process.
Position of larval tapeworms, Polypocephalus sp., in the ganglia of shrimp, Litopenaeus setiferus
Integrative and Comparative Biology, 2014
Parasites that invade the nervous system of their hosts have perhaps the best potential to manipulate their host’s behavior, but how they manipulate the host, if they do at all, could depend on their position within the host’s nervous system. We hypothesize that parasites that live in the nervous system of their host will be randomly distributed if they exert their influence through non-specific effects (i.e., general pathology), but that their position in the nervous system will be non-random if they exert their influence by targeting specific neural circuits. We recorded the position of larval tapeworms, Polypocephalus sp., in the abdominal ganglia of white shrimp, Litopenaeus setiferus. Tapeworms are more common within ganglia than in the section of the nerve cord between ganglia, even though the nerve cord has a greater volume than the ganglia. The tapeworms are also more abundant in the periphery of the ganglia. Because most synaptic connections are within the central region of the ganglion, such positioning may represent a trade-off between controlling the nervous system and damaging it.
2016
Synopsis Parasites that invade the nervous system of their hosts have perhaps the best potential to manipulate their host’s behavior, but how they manipulate the host, if they do at all, could depend on their position within the host’s nervous system. We hypothesize that parasites that live in the nervous system of their host will be randomly distributed if they exert their influence through non-specific effects (i.e., general pathology), but that their position in the nervous system will be non-random if they exert their influence by targeting specific neural circuits. We recorded the position of larval tapeworms, Polypocephalus sp., in the abdominal ganglia of white shrimp, Litopenaeus setiferus. Tapeworms are more common within ganglia than in the section of the nerve cord between ganglia, even though the nerve cord has a greater volume than the ganglia. The tapeworms are also more abundant in the periphery of the ganglia. Because most synaptic connections are within the central ...
Journal of Fish Diseases, 1978
SoccuZwiagrani/'era was found in 12% of commercial sandcrabs, Portunus pelagicus, in Moreton Bay irrespective of sex. Although male and female crabs were randomly distributed about Moreton Bay, egg bearing females were most common at the seaward station. This and the distribution of epizoic barnacles on gills and carapace suggest the sexes school separately. The increased prevalence of barnacles on the carapace of infected crabs indicates Sacculina inhibits moulting. The distribution of interna infections in small crabs towards south and west and externa infections in large crabs in the easterly, seaward stations suggests Sacculina preferentially attacks young crabs as they move inshore and then induces crabs to behave like "berried' (i.e. egg bearing) females by moving seaward as they grow. Morphologically female crabs are little changed by Sacculina, but the males show considerable modification which is reflected most accurately in the shortening ofthe chelar propodus to proportions similar to normal females. Infected crabs are sterile and internally the hepatopancreas becomes green rather than tan. Parasitized crabs were seen to groom their externae as 'berried' females groom their egg masses.
Journal of Fish Diseases, 1979
The behaviour of crabs Portunus pelagicus infected with the rhizocephalan barnacle Sacculina granifera is examined and compared with that of normal uninfected crabs. With regard to alarm reactions, feeding and locomotion, the infected crabs behave as normal crabs. Their stance, defaecation and burying behaviour differ in that they must accommodate to the physical presence of a large body, the parasite, suspended between cephalothorax and abdomen. General body care is increased as a result of the increased epizoic fauna on the exoskeleton which develops when moulting ceases. Infected crabs with an externa resemble ovigerous females in terms of their moderate daylight activity and particularly the grooming care and attention given to the sac-a surrogate egg mass. Parasitized crabs excavate a depression and using the third walking legs (and often second and first as well) attend the externa as an ovigerous female attends her egg mass. The grooming of the externa is of equal periodicity to egg mass grooming behaviour, but is less prolonged at maximum intensity. Sac grooming behaviour begins 18 days after emergence of an externa and declines progressively if the externa is removed and the interna degenerates. In interactions with other crabs parasitized individuals initiate fewer and dominate fewer encounters than normal crabs of similar size and sex; and parasitized males, at least, are less active when with other crabs than when alone. It is concluded the parasite secretes a hormonal mimic which induces ovigerous behaviour which maximizes the survival of the parasite population.
Parasite Distributions in Arboreal and Semi-Aquatic Crabs of Cockroach Bay, Florida
Zenodo (CERN European Organization for Nuclear Research), 2022
The mangrove crab Aratus pisonii and fiddler crabs Leptuca pugilator and Minuca pugnax belong to two different families of crabs, yet inhabit the same mangrove swamps found throughout Florida. Literature regarding parasitic infections for all three species of crabs is scant, yet it is known that parasites which infect crabs can reduce survivability, cognitive function, and the ability to reproduce in their hosts. We tested the hypothesis that fiddler crabs will have significantly different mean parasite abundance when compared to the mangrove crabs due to fiddler crabs' semi-aquatic lifestyle and greater interaction with substrates within Cockroach Bay in Tampa, Florida. From the 25 juvenile nematodes found, the sand fiddlers and marsh fiddlers had a higher prevalence percentage than the mangrove crabs with 61.5% and 26.7% respectively. Utilizing a 2-sample t-test analyzing mean nematode abundance per crab species, we found a p-value of .013 between the mangrove crab and marsh fiddler, supporting our hypothesis that fiddler crabs will have a greater parasite intensity than the mangrove crabs. Furthermore, we discovered two members of the parasitic isopod Leidya disorta within two members of Minuca pugnax, a novel discovery of Bopyrid isopods within Minuca pugnax of Cockroach Bay.