Host characteristics and infection level of an intestinal parasite Corynosoma strumosum (Acanthocephala) in the Kuril harbor seal of Erimo Cape, Hokkaido, Japan

Kaimoto, Tadashi; Hirazawa, Takuya; Masubuchi, Takahito; Morohoshi, Aya; Katahira, Hirotaka; Kobayashi, Mari

doi:10.1016/j.parint.2017.12.008

Cited by 10 publications

(13 citation statements)

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“…These features additionally reduce frictional drag, which helps females withstand the harsh microhabitat conditions in the stomach longer than males [14]. Corynosoma strumosum and C. magdaleni favour the jejunum and proximal ileum [30–32]. Rheological conditions in this microhabitat are expected to be more benign because peristaltism is less intense and the digesta more fluid than in the stomach.…”

Section: Discussionmentioning

confidence: 99%

Morphology, performance and attachment function in Corynosoma spp. (Acanthocephala)

2018

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BackgroundFunctional inference on the attachment of acanthocephalans has generally been drawn directly from morphology. However, performance of structures is often non-intuitive and context-dependent, thus performance analysis should be included whenever possible to improve functional interpretation. In acanthocephalans, performance analysis of attachment is available only for Acanthocephalus ranae, a species that solely relies on the proboscis to attach. Here we compare body morphology and muscle arrangement in 13 species of Corynosoma, which use their spiny body as a fundamental holdfast. A basic performance analysis using live cystacanths of two representative species is also provided.MethodsAdults of 13 Corynosoma spp. were obtained from 11 marine mammal species. Specimens were cut and carefully cleaned to examine muscle arrangement through light and scanning electron microscopy. Live cystacanths of C. australe and C. cetaceum were selected for performance analysis. Video records of evagination-invagination cycles of the proboscis were obtained and analysed with a video editor.ResultsThe basic arrangement of proboscis retractors, trunk circular and longitudinal muscles, neck retractors and receptacle retractors, was conserved in all Corynosoma species. Interspecific variability was found in the relative development of disk muscles: minimum in C. enhydri, maximum in C. cetaceum; the distal insertion of the ventral neck retractor: ventro-lateral in C. cetaceum, C. hamannni and C. pseudohamanni and ventral in the other species; and the distal insertion of the receptacle retractors: more proximal in species with a longer hindtrunk. Performance analysis indicated striking similarities to that described for A. ranae except that (i) the foretrunk bends ventrally during the evagination-invagination cycles of the proboscis; (ii) disk muscles can flatten the tip of the foretrunk regardless of these cycles; and (iii) the receptacle bends ventrally and is driven to the hindtrunk by coordinated action of receptacle retractors.ConclusionsSpecies of Corynosoma are able to use up to six holfast mechanisms. Attachment relies on a similar performance to that described for A. ranae. However, structural ventral bending of an inflated, spiny foretrunk, with a parallel re-arrangement of foretrunk muscles, have generated unexpected novel functions that make attachment extremely effective in species of Corynosoma. Interspecific variability in trunk shape and muscle arrangement grossly correlates with the rheological conditions each species experiences in their microhabitats within the gut of marine mammals.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3165-1) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Morphology, performance and attachment function in Corynosoma spp. (Acanthocephala)

2018

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“…Clustering of Corynosoma species within microhabitats of the intestine has been reported (Helle & Valtonen, 1981;Valtonen & Helle, 1988;Nickol et al, 2002;Kaimoto et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Corynosoma strumosum in seals tend to congregate just past the midgut, and C. semerme has adapted to life in the nutrientpoor colon of seals (Helle & Valtonen, 1981;Nickol et al, 2002;Kaimoto et al, 2018). These two species differ in size and proportion, with C. semerme being smaller and stouter, with a shorter trunk than C. strumosum (Valtonen & Helle, 1988).…”

Section: Introductionmentioning

confidence: 99%

“…Prevalence of infection with C. enhydri in southern sea otters has been seen at 90% (Hennessey & Morejohn, 1977) and 94.4% (Mayer et al ., 2003), while northern sea otters were observed to have a prevalence of 51% (Margolis et al ., 1977). Prevalence of Corynosoma infections in seals showed strong variability in geographic location and, over time, measured 56% in the Baltic ( n = 26) (Nickol et al ., 2002), 23% in the Wadden Sea ( n = 23) (Lehnert et al ., 2007), 87.5% in Japan ( n = 40) (Kaimoto et al ., 2018), 100% in Ireland ( n = 26) (O'Neill & Whelan, 2002) and 29.5% in Alaska ( n = 105) (Kuzmina et al ., 2012). This difference may be due to host species location, diet and availability of fish intermediate hosts (Nickol et al ., 2002).…”

Section: Introductionmentioning

confidence: 99%

“…GI tracts were thawed overnight if frozen, then cleaned of the mesentery and omentum by careful removal with a scalpel. The intestine was laid out in full; the small intestine was measured for total length, and cut into five equal sections, the large intestine left intact as the sixth (Nickol et al, 2002;Sinisalo et al, 2003;Aznar et al, 2004;Kaimoto et al, 2018). Each section was then opened, and parasites were removed with soft forceps.…”

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Habitat selection and populations ofCorynosoma(Acanthocephala) in the intestines of sea otters (Enhydra lutris) and seals

et al. 2020

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Acanthocephalans are common intestinal parasites of marine mammals, the most widespread of which is the genus Corynosoma. In this study, parasite infrapopulations of two closely related species of Corynosoma were examined: Corynosoma enhydri from sea otters (Enhydra lutris) in Alaska (n = 12) and California (n = 19), and Corynosoma strumosum from seals in Germany (n = 22). Prevalence of C. enhydri was 100% in Californian otters, with a mean abundance of 30, and 83% in Alaskan otters, with a mean abundance of 232. In seals, C. strumosum had a prevalence of 65%, with a mean abundance of 33. Female C. enhydri dominated both Californian (82%) and Alaskan (79%) infections, while, in seals, female C. strumosum made up 68% of the parasite population. Reproduction rates for C. enhydri, with 16% (California) and 18% (Alaska) of females mated, were low compared to C. strumosum in seals, of which 40% of females were mated. Habitat selection also differed significantly between the two species. Corynosoma enhydri was found most frequently in the second and third fifths of the small intestine, while C. strumosum was found most frequently in the fourth. The differences in habitat selection and prevalence analysed in this study may be related to a trade-off between growth and reproduction between the two species.

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Morphological identification in skull between spotted seal and harbor seal using geometric morphometrics

Kanaiwa

Kato

Kobayashi

2021

Journal of Morphology

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The morphology of the skull contains considerable ecological information about a species, because the skull contains sensory organs that are used to look for food, compete for mates, or to migrate. Spotted seals (Phoca largha) and harbor seals (Phoca vitulina) are similar in body size and pelage color but differ in habitat use and reproductive biology. The current study aims to clarify differences in the shapes of skulls in the spotted and harbor seals using geometric morphometrics and to discuss whether ecological differences can explain morphological differences in skulls. First, we discovered that the age at which the shape of skulls stopped changing was 7 years in both species, using the linear‐threshold model. Using a total of 75 landmarks, 54 individuals (25 spotted seals, 29 harbor seals) that were older than the age at which skulls stopped changing were correctly identified at a rate of 100%. The total of 75 landmarks was narrowed down to eight key landmarks that resulted in an identification accuracy rate of 100% using random forests. Of the eight landmarks, seven were related to feeding apparatus, indicated that the harbor seal had a broader mouth and mandible than the spotted seal. Because of both species were dietary generalists and classified as pierce feeders, we suggested that the different features in the shapes of their skulls were caused not only by differences in their feeding behavior but also other differences related to reproductive behavior.

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Host characteristics and infection level of an intestinal parasite Corynosoma strumosum (Acanthocephala) in the Kuril harbor seal of Erimo Cape, Hokkaido, Japan

Cited by 10 publications

References 42 publications

Morphology, performance and attachment function in Corynosoma spp. (Acanthocephala)

Morphology, performance and attachment function in Corynosoma spp. (Acanthocephala)

Habitat selection and populations ofCorynosoma(Acanthocephala) in the intestines of sea otters (Enhydra lutris) and seals

Morphological identification in skull between spotted seal and harbor seal using geometric morphometrics

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