Canadian Journal of Zoology

Published by NRC Research Press
Online ISSN: 1480-3283
Publications
Article
Male laboratory mice were isolated for 3 weeks after weaning before being placed in groups of 1, 2, 4, 8, 16, and 32 animals. The groups were placed into cages of increasing size; so space per mouse remained constant. Indicator organs were weighed to determine the effect of the increasing number of social interactions. Weights of spleen and adrenal glands showed that hypertrophy increased as the number of possible social interactions increased. Testes development was inhibited by an increased number of possible social interactions. Populations may be regulated by increasing the number of social contacts without decreasing the space per animal.
 
Article
Rainbow trout (Salmo gairdneri) were fed dietary levels of 0-, 1-, 10-, and 100-ppm Aroclor 1254 for 229 to 330 days. The ultrastructural features of control livers were similar to those of other animals, but rainbow trout liver differed from mammalian liver in an apparent absence of Kupffer cells. Also small dense duct-type cells were present that formed a transition zone, combining with hepatocytes to form canaliculi; alone they formed preductules and in combination with cells of lower density they formed ductules. Microtubules were found in the vicinity of canaliculi and less frequently adjacent to the plasma membrane of other cell surfaces. They were not seen at the sinusoidal border as they are in mammalian liver. Peroxisomes lacked nucleoids. There were no ultrastructural liver changes in the 1-ppm group. The most frequently encountered alterations in both the 10- and 100-ppm groups were those involving the nucleus. These included irregular and bizarre nuclear outlines, separation of nucleolar components, and large nuclear pseudoinclusions. Other frequently encountered changes were slight increases in smooth endoplasmic reticulum, altered rough endoplasmic reticulum, increased lysosomes, reduced and altered glycogen, increased lipid, and hypoxic vacuoles. Seen also were concentric membrane arrays, myelin figures in intercellular spaces and Golgi cisternae, and bundles of fine tubules throughout the cytoplasm.
 
Article
90Sr and 137Cs were determined in 11 different tissues of the fin whale and 2 different tissues of the harp seal. Muscle tissue in most instances contained more 137Cs than did the other tissues that were examined. The average concentration of 137Cs in whale muscle was 4.5 pCi/g ash and in adult seal muscle was 2.5 pCi/g ash. The highest concentration (3.5 pCi/g ash) of 90Sr was found in whale blubber.
 
Article
Sodium-1-14C-acetate was injected into larvae of the parasite, Exeristes comstockii, reared on Galleria mellonella or on Lucilia sericata. The concentration and specific activities of the fatty acids in the larvae were measured 24 h later. The concentration of palmitoleic acid was 10 times greater in C. comstockii when it grew on L. sericata but the specific activity of this fatty acid was the same on either host. It is concluded that the level of palmitoleic acid and probably other fatty acids in the parasite is controlled predominantly by changes in metabolic rates which are regulated by the concentration of the fatty acid in the parasite's diet, that is, host tissue. Direct deposition of dietary fat would not accomplish this result.Another parasite, Itoplectus conquisitor, reared on G. mellonella was also examined.
 
Article
Rana sylvatica tadpoles were treated with 0.001 and 0.003 ppm [14C]DDT (1,1,1 -trichloro-2,2-bis(p-chlorophenyl)ethane) at 15 and 21 °C and the time course of uptake and residue levels in several tissues of contaminated tadpoles were studied. By 24 h post treatment, highest concentrations of DDT were found in whole animals and in isolated tadpole tissues. After 80 h, DDT tissue levels began to diminish and fall slowly throughout the duration of the experiment. Liver and fat were the main sites for pesticide deposition. Tadpoles treated at 15 °C retained higher tissue levels of DDT for longer periods, i.e., they lost DDT more slowly than tadpoles at 21 °C.
 
Article
Groups of yearling coho salmon held at 10 °C on a natural photoperiod, and fed excess ration daily, were administered either bovine growth hormone (bGH; 0.0092 IU/g body weight), L-thyroxine (T4; 1 μg/g), 17α-methyltestosterone (MT; 1 mg/kg diet), combinations of these hormones, or no hormone for 59 days. Fish received bGH and (or) T4 intramuscularly once weekly.Each individual hormone and hormone combination significantly enhanced growth. The sequence noted for growth rate of the groups was as follows: (bGH + MT + T4) > (bGH + MT) > (bGH + T4) > bGH > (T4 + MT) > MT > T4 > control groups. Three hormonal interactions were additive (T4 + MT; bGH + MT; bGH + MT + T4). The growth rate of fish treated with bGH + MT + T4 was over three times that of the controls.T4 or MT + T4 administration significantly increased condition factors, while MT, bGH, bGH + T4, bGH + MT, and bGH + MT + T4 decreased them.Significant elevations in percentages of muscle water (bGH) and lipid (T4; T4 + MT; bGH + MT) were found. Thyroid activity (follicle epithelial height) was significantly increased in MT and MT + bGH fish, but depressed in T4 fish. Hormone administration altered the histological structure of the endocrine pancreas (bGH and MT groups), ovary (bGH; MT groups), testis (MT groups), and interrenal tissue (bGH; MT).
 
Article
Lungworms were collected from 60 harbor porpoises shot at sea during May to August of 1970 and 1971 in the Bay of Fundy. These have been compared with related species from other odontocetes in order to evaluate the literature on pseudaliids and provide a consistent treatment of the family. This study also gives data on the occurrence of lungworms in odontocetes from Canadian waters. Keys to genera and selected species of pseudaliids in cetaceans are included.The following are redescribed: Pseudalius inflexus (Rudolphi 1808), Stenurus minor (Kuhn 1829), Torynurus convolutus (Kuhn 1829), Halocercus invaginatus (Quekett 1841), and H. taurica Delyamure, in Skrjabin 1942 from harbor porpoise, Phocoena phocoena, collected in eastern Canada; Stenurus globicephalae Baylis and Daubney 1925 from Globicephala melaena, G. macrorhyncha, and Grampus griseus (new host record); Stenurus arctomarinus Delyamure and Kleinenberg 1958 and Pharurus pallasii (van Beneden 1870) n. comb, from Delphinapteras leucas; Torynurus dalli (Yamaguti 1951) from Phocoenoides dalli; and Pharurus alatus (Leuck-art 1848) from Monodon monoceros. Pseudalius inflexus, H. taurica, and S. arctomarinus are reported for the first time from North American hosts; S. globicephalae, P. pallasii, P. alatus, and all the pseudaliids from Phocoena phocoena are reported from new host localities.Torynurus alatus is considered a synonym of Pharurus alatus. Stenurus arcticus (including previously proposed synonyms Strongylus arcticus, Pseudalius arcticus) is considered a synonym of Pharurus pallasii.Halocercus ponticus Delyamure 1946 is considered synonymous with H. invaginatus.
 
Article
Cestodes representing six species of the genus Diphyllobothrium Cobbold, 1858, were collected from naturally infected terrestrial mammals in Alaska during the period 1949-1970. Additional specimens were reared in experimentally infected animals. Of the species identified, viz., D. latum (Linnaeus, 1758), D. dendriticum (Nitzsch, 1824), D. lanceolatum (Krabbe, 1865), D. ursi Rausch, 1954, D. dalliae Rausch, 1956, and D. alascense Rausch and Williamson, 1958, all but D. alascense were obtained from man after treatment with quinacrine. D. latum occurred most commonly in humans; D. ursi is reported for the first time from this host, and D. lanceolatum in humans was represented by a single plerocercoid. D. lanceolatum, a characteristic parasite of phocids, was found also in dogs; D. alascense was obtained only from dogs. In humans, rate of infection by Diphyllobothrium spp. were highest in the delta region of the Kuskokwim and Yukon Rivers, western Alaska. Included is a description of D. latum and a discussion of morphologic variation, based upon specimens from Alaska, with a consideration of differential characters of the other species reported. Some biological characteristics of these cestodes are briefly discussed.
 
Article
A quantitative and histochemical study of Ms. pectoralis, gluteus, psoas, diaphragma (dorsal, lateral, and ventral parts separately) of the harp seal was carried out. Myoglobin and iron contents of all the muscles were high, highest being of M. psoas. Fat and glycogen were low in all muscles. The low glycogen value was possibly due to rapid glycolysis during struggle in capture and while the animal was under an overdose of sodium pentobarbital that was administered for killing it. Phosphorylase and succinate dehydrogenase (SDH) activity levels were also low. Lipase (tributyrinase) activity was high, that of M. diaphragma being higher than the other muscles studied. The histochemical investigation revealed some of the morphological and biochemical properties of the component fibers. Two types of fiber, the red (type 1) and white (type 2), comparable to those of other skeletal muscles were distinguished in all muscles except in the case of M. pectoralis where an intermediate type was also seen in sections treated for the histochemical demonstration of SDH activity.The low levels of fat and SDH in the muscles indicate that fat is not a favored metabolite for muscular energy. The significance of the high lipase (tributyrinase) activity is doubtful. It is suggested that the role of this enzyme is to clear the fat so as to prevent the accumulation of fat in the muscles which are, by and large, geared for a glycolytic metabolism as an adaptation for the animal's diving habit. The high myoglobin content of the muscles, however, should provide the oxygen necessary for the oxidation of glucose during the initial part of the dive.
 
Article
The large, heavy ossicles of Pagophilus groenlandicus are firmly attached to the epitympanic wall by a single fold of epitympanic mucosa. The epithelium of the middle ear mucosa is pseudostratified columnar epithelium. Large cavernous sinuses are present below the dense collagenous fibers of the submucosa. The cavernous sinuses are prominent around the promontory and the medial wall of the tympanic orifice of the auditory tube, and also in the tympanic sulcus of the tympanic membrane. The distension of the cavernous tissue may aid in hearing.The wall of the auditory tube consists of thick collagenous and elastic fibers. The medial wall is a thick fibrous block of connective tissue. Hyaline cartilage forms the central core of the thick fibrous medial wall of the auditory tube. The robust wall of the tube makes it unlikely that the tube wall is collapsed by the increase pressure in the nasopharynx during diving. Pressure equilibration during diving may be achieved by the opening of the nasopharyngeal orifice by muscular contraction. The closing of the tube may be achieved by the elasticity in the tube wall.
 
Article
The retina of the harp seal (Pagophilus groenlandicus) was studied by means of the light microscope. Ganglion cells occupy a single layer. Thinly dispersed throughout this layer are giant ganglion cells. There is no area centralis. The inner nuclear layer consists of large horizontal cell processes with bipolar and amacrine cells between the horizontal cell processes. The outer nuclear layer is the thickest of all retinal layers. Its density is constant in the central and peripheral areas of the retina, similar to that found in the inner nuclear and ganglion layers. Only rod photoreceptors were found; therefore it is presumed that seals have no color vision. The tapetum covers an extensive area and is 32–34 cellular layers thick centrally, diminishing in thickness peripherally. The combination of tapetum and rod receptors makes possible excellent visual sensitivity to dim light.
 
Article
The surface preparation technique was used to estimate the sensory cell population and density in the organ of Corti of seven harp seals and four ringed seals. The average total of inner hair cells for the harp seal was 3654 (3078–263) as compared with an average total of 3232 (3120–3354) in the ringed seal. The average total number of outer hair cells in the harp seal was 14 318 (12 173 – 15 709) as compared with an average total of 13 497 (12 903 – 14 894).The distribution of outer and inner hair cells showed an increase in density from base to apex. An increase in density of about 21% and 29% was observed in the inner hair cells of the ringed and harp seal. The increase in density for each row of outer hair cells was 21% in the harp seal and 17% in the ringed seal. The density of outer hair cells per unit surface area decreased from a maximum value at the base to about half its value at the apex.The average total sensory cells of seals exceeded the average total sensory cells of both man and dolphin but were within the range of variation of the human.
 
Article
Surface preparations of the organ of Corti of four harp seals were used to study the effect of prolonged ingestion of methyl mercury on the sensory cell population.A low level of damage to the sensory hair cells occurred throughout the length of the cochlea. Damage was confined to the three outer rows of sensory hair cells especially the third outermost row. At each location along the length of the cochlea, sensory hair cell damage in the seals on a daily dose of 25.0 mg/kg of methyl mercury exceeded the damage to the cochlea of the seals fed on a daily dose of 0.25 mg/kg of methyl mercury. Greatest damage in all the mercury-treated seals occurred in the middle coil of the cochlea. Seals on the higher mercury diet showed a 20–24% sensory cell damage at the upper middle coil, about 19–26 mm from the base, whereas only 4–5% damage was found within same region in the cochlea of the seals on the lower mercury diet.This lack of specificity and low level of damage to the sensory hair cells seems characteristic of mercury and is a direct contrast to other known ototoxic agents.
 
Article
Methods of capturing harp seals and maintaining them in captivity are described, and the molt and symptoms of various diseased animals are discussed together with postmortem findings.
 
Article
A free-field underwater audiogram from 0.76 to 100 kHz was obtained for Pagophilus groenlandicus. Areas of increased sensitivity occurred at 2 and 22.9 kHz. The lowest threshold was −32.9 db/μbar at 15.0 kHz. Above 64 kHz the threshold increases at a rate of 40 db/octave. The audiogram was similar to that of the Phoca vitulina. The effects of ambient noise on the audiogram are discussed.
 
Article
The gross and microscopic structure of the auditory meatus of the harp seal (Pagophilus groenlandicus) is described from dissections and serial sections. The meatus bends ventrally from the oval external orifice, posteroventrally, ventrally, and finally medially into the cranium. The ventrally directed wall of the meatus is membranous, the posteroventral and ventrally directed wall is incompletely wrapped by cartilage, and the medially directed wall is bony. The areas between sections of the cartilaginous wall ate completed by connective tissue. The meatus is closed internally by the intrinsic helicis and antitragicus auricular muscles. The external orifice is closed by the superficial auricular muscles. The auditory meatus is lined with stratified squamous epithelium, sebaceous glands, and ceruminous glands. Longitudinal blood sinuses and elastic fibers in the hypodermis may function as a pressure regulating device during diving. Blood sinuses are most prominent in the bony region of the meatus and extend into the tympanic sulcus of the pars tensa. Blood sinuses engorged with blood and a closed meatus may enhance transmission of sound to the tympanic membrane when the seal is under water.
 
Article
The normal levels of haemoglobin, iron, certain metabolites (glucose, fat, and cholesterol) and enzymes (amylase, aldolase, lactic dehydrogenase, and lipase/esterase) in the blood of the harp seal were estimated. All values except for the lipase (esterase), were considerably higher than those recorded for other animals, including man. The elevated level of lactic dehydrogenase activity as a normal characteristic of the blood is attributed to the role of the enzyme in the oxidation of lactic acid to pyruvate as an adaptation in a diving animal. The extremely low level of lipase (esterase) activity in the blood is suggested to be indicative of the fact that fat is not the favored metabolite for muscular energy in a diving animal.
 
Article
An electron microscopic study of the structure of three skeletal muscles, pectoralis major, psoas, and longissimus dorsi, of the harp seal (Pagophilus groenlandicus) was carried out. Two types of fiber, the dark and the light comparable to the red (type 1) and the white (type 2) of other vertebrate skeletal muscles, were recognized while a third, the intermediate type, could be clearly distinguished only in the pectoralis major. All the fiber types contained considerable amounts of glycogen, while large aggregations of mitochondria and lipid droplets were seen only in the dark fibers.The intermyofibrillar matrix in the fibers of the pup (< 3 months) muscle was found to be more extensive than that of the adult muscle. The dark fibers in M, longissimus dorsi of both the pup and the adult appeared to have higher mitochondrial density than those of the other two muscles studied, thereby indicating that this muscle had a greater capacity for aerobic metabolism than M. psoas, which in turn had a larger population of mitochondria than M. pectoralis major. Though the presence of large mitochondrial aggregations and lipid droplets suggests the possibility of fat being used as fuel for muscular energy, it is postulated that the seal muscle is basically geared for anaerobic use of carbohydrate as an adaptation for the animal's diving habit. However, aerobic metabolism of carbohydrate and of a limited amount of fat may be used during surface swimming. It is also suggested that the mitochondrial aggregations and lipid droplets in the dark fibers of both adult and pup muscles represent an adaptation for thermogenesis comparable to that of the brown adipose tissue.
 
Article
The structure of the large vestibular apparatus of the harp seal (Pagophilus groenlandicus) is similar to that of other mammals. However, the posterior semicircular canal is the smallest of the three canals and the plane of the lateral is below that of the posterior semicircular canal. An additional sensory end organ (crista neglecta) is present about 0.75 mm from the posterior crista. The neuroepithelium of the crista neglecta is similar to that of the crista of the semicircular canals and consists of large supporting and sensory cells, the sensory hairs of which project into the cupula. No otoconia were seen on the crista neglecta as were present on the otolithic membrane of the maculae utriculi and sacculi. A large macula utriculi and crista neglecta may be necessary for body orientation during diving.
 
Article
A free-field air audiogram from 1 to 32 kHz was obtained for a Pagophilus groenlandicus trained to respond to pure tone signals. The lowest threshold was at 4 kHz at a level of 29 db//0.0002 dynes/cm2. The air audiogram was generally flat. The critical ratios at 2 and 4 kHz were 10%. The lumen of the external auditory meatus is probably acoustically blocked. The outer and (or) middle ear structures and their acoustic impedance mismatch with the air are believed responsible for the comparatively irregular and slightly insensitive hearing of the seal in air.
 
Article
Behavioral determinations of harp seal spectral sensitivity, under light- and dark-adapted conditions, indicated the presence of a Purkinje shift. Maximum photopic sensitivity occurred near 550 nm. Scotopic sensitivity peaked in the region of 500–525 nm. A large increase in relative sensitivity, approaching 8 log units at 525 nm, accompanied dark adaptation. This confirms anatomical suggestions that the harp seal possesses excellent visual sensitivity. Increased sensitivity to green wavelengths may indicate adaptation to a particular underwater environment.
 
Article
The population and density of the bipolar ganglion cells were determined from serial horizontal sections and graphic reconstructions of the cochleas of five captive harp seals. The -turn spiral ganglion forms a continuous ring throughout its course except at the extreme basal end where it is narrowest. The nerve cell body is 25 μm long (16.1–38.8 μm) and 16 μm wide (10–24 μm). The average number of ganglion cells present was 57 185 (46 389 – 70 952), with a corrected total number of 52 000 ganglion cells. Two peaks are present in the density curve of the ganglion cells. The first was at 1–1.5 mm and the second at 20 mm, where 2620 cells/mm2 and 2250 cells/mm2 respectively are present.The ratio of total ganglion cells to total sensory hair cells was about 3:1. This ratio was not uniform throughout the length of the cochlea; it was 6:1 at 2–3 mm from the basal end and declined gradually to 3:1 at the apical end. The average total of ganglion cells in the harp seal exceeded the average value in humans, but did not exceed the values found in dolphins.
 
Article
An examination of 246 mink, Mustela vison Schreber, from both southeast and southwest Manitoba, showed Dioctophyme rénale in three animals from the former area but none in the latter. This is the first record of D. renale from wild mammals in Manitoba.
 
Article
Paruterina candelabraria was found in 4 out of 40 rodents collected in gravel pits near St. Lupicin, Mulvihill, Wasagaming, and Lockport, Manitoba. The hosts were Microtus pennsylvanicus and Peromyscus maniculatus. Cladotaenia globifera was found in 1 out of 15 M. pennsylvanicus collected near Bissett, Manitoba.
 
Article
Dioctophyma renale was found in the right kidney of 48% of mink (Mustela vison) trapped in late fall and winter in the Black River area of Ontario. Eggs embryonated at temperatures from 14 C to 30 C. Eggs hatched in the intestine of the aquatic oligochaete Lumbriculus variegatus, and first-stage larvae migrated to the ventral blood vessel where development took place. The first molt occurred about 50 days after infection in oligochaetes kept at 20 C; the second molt occurred about 100 days after infection. Third-stage larvae removed from oligochaetes produced infection in a mink. Larvae given to frogs (i.e. Rana clamitans, melanota and R. pipiens) became encapsulated in the stomach wall or abdominal muscles. A mink was infected with larvae removed from frogs experimentally infected 25 days earlier. A mink was also infected with larvae found in a naturally infected bullhead (Ictalurus nebulosus). Infective larvae of D. renale were found in wild Rana catesbeiana (6.2%), R. septentrionalis (9.6%), and R. clamitans melanota (0.7%) in an area enzootic for dioctophymiasis. It is suggested frogs as well as bullheads are important natural paratenic hosts for D. renale. The various larval stages of D. renale are described and its third-stage larva is distinguished from that of Eustrongylides spp. which may also be found in frogs.
 
Article
The acanthocephalan Echinorhynchus salmonis showed a marked seasonality of occurrence in the yellow perch Perca fluviatilis in the Bay of Quinte, Lake Ontario. The incidence of the parasite started increasing in autumn and reached a peak in late winter. It started decreasing in March and fell to zero in August or September. Such seasonality has been previously observed for acanthocephalans in bodies of water which freeze, as does the Bay of Quinte. There is a single egg maturation period for the parasite in early summer, after which the parasites die. Infestation of intermediate hosts occurs in spring when the population of the hosts is high. The subsequent warm period ensures rapid development of the parasite. Within the fish the parasite is less affected by the lower temperatures prevailing in winter. No influence was apparent between the maturity and seasonality of the parasite and the food and breeding cycle of the fish.
 
Article
The 'tunnel' within which the nematode Trichuris muris is contained was examined by light, scanning, and transmission electron microscopy. The amount of worm covered by the tunnel varied with age. Young larval worms were completely embedded in the host's intestinal mucosa whereas older larvae and adults had part, if not all, of the posterior region protruding into the lumen. All worms were found to have heads embedded in the tissue and in no cases were whole worms found free in the lumen.The 'tunnel' was shown to be a syncytial protoplasmic mass with recognizable cellular elements such as nuclei, lipid droplets, mitrochondria, and mucous droplets anteriorly whereas more distal to the head these elements became increasingly scarce and degenerated. The syncytium is bordered apically, laterally, and basally by cell membrane. The basal lamina can be identified beneath the basal membrane of the syncytium indicating that syncytium formation occurs in the epithelial sheet only and does not extend into the lamina...
 
Article
The functional organization and cytochemistry of the epidermis of an air-breathing fish, Channa striata, is described. In the basal cells a dense population of mitochondria, strong alkaline phosphatase, and succinic dehydrogenase activity indicates high metabolic activity. In the outermost layer, polygonal cells showed strong succinic dehydrogenase activity and elaborated sulfated acid mucopolysaccharides and lipids. Mucous cells were also numerous. A new term, 'sacciform granulated cells,' is proposed for the 'sacciform cells' or 'granular cells.' The contents of these cells are basic proteins. A thick coat of slime containing mucopolysaccharides, lipids, and basic proteins is probably important in keeping the skin moist for cutaneous respiration, retarding the rate of water loss by evaporation, facilitating burrowing in the mud and swimming movement in water, and protecting the skin from bacterial and fungal attacks. A relatively thin epidermis (32 μm on the general surface, 18 μm at the posterior free margins, and 6 μm below the scales) in conjunction with vascularization of the stratum laxum probably assists cutaneous respiration.
 
Article
The structure and the cytochemistry of the dermis and the subcutis of Channa striata, which buries in mud to survive droughts, is described and correlated with its habitat. The dermis consists of an outer stratum laxum and an inner stratum compactum. The stratum laxum is mainly composed of well-developed scales lodged in connective tissue pockets which are characterized by the presence of huge deposits of lipids. These lipids may play important roles: in supplying energy during the period of fasting, acting as a barrier for water diffusion through the skin, and serving as shock absorbers, protecting the body from mechanical injury during burrowing. The presence of sulfated acid-mucopolysaccharides, the substantia amorpha in the stratum laxum, has been described as an adaptation to prevent desiccation. Alkaline phosphatase, sulfated acid-mucopolysaccharides, and calcium are closely associated in the osseous layer of the scales and probably play an important role in calcification. Numerous fine collagen fiber strands connecting the basement membrane to the scales provide firm attachment of the epidermis to the dermis. The presence of a relatively thin subcutis may be correlated with the well-developed layer of fat cells in the stratum laxum.
 
Article
Juvenile coho salmon (Oncorhynchus kisutch) held in 11 °C fresh water (FW) were fed Oregon moist pellets supplemented with 3,5,3′-triiodo-L-thyronine at 4 ppm (T34) or 20 ppm(T320) and (or) 17α-methyltestosterone at 0.2 ppm (MT0.2) or 1 ppm (MT1) until early or normal seawater (SW) transfer.During FW residency all hormonal treatments improved growth, appetite, and food utilization. In February, fish fed T320 singly or with MT had increased degranulation of somatotrop cytoplasm. Thyroid epithelial cell height of fish fed T34 or T320 was either suppressed or enhanced. MT1 singly or combined with T3 induced androgenic side effects in males. Proximate body composition was affected only by MT. T320 induced morphological anomalies and treatment was discontinued. In May, thyroid activity and number of putative gonadotrops of fish fed MT1 were increased. Androgenic effects of all groups given MT1 were greater in May than in February.After SW transfer in February growth, appetite, and food utilization were depressed but fish fed T34 performed better than controls. Performance of all groups improved after May but, in general, mortality increased slightly. After transfer in May, T3-fed fish had increased growth in length.It is concluded that MT and T3 effectively enhance growth in FW but only T3 facilitates SW transfer.
 
Article
Cysticerci of Taenia crassiceps were found in Microtus pennsylvanicus drummondii (Aud. and Bach, 1853) in Fort Gary municipality of Greater Winnipeg. A vegetatively propagated strain of these cysticerci was established in LDF1 mice, and their growth studied in other rodents.
 
Article
Eggs of Contracaecum osculatum were dissected from the vagina and uterus of adult worms from seals and were incubated in seawater at 15C. Freshly hatched larvae were cultivated to preadult in Eagle's medium (MEM) with 20% foetal calf serum.At 15C, the ensheathed second-stage larvae exsheathed and grew to the infective stage without further molts. Infective larvae of C. osculatum were 6.5 mm (5.9–9.5) in length after 32 weeks.At 35C, 58% of infective larvae > 2 mm in length molted to subadults which possessed cuticular lips but lacked interlabia. Subadults were 2.9–13.8 mm in length and morphologically similar to larvae found attached to the gastric mucosa of seals. Four subadults subsequently molted to preadults 13.1–17.2 mm in length with interlabia. However, an attempt lo infect a seal with cultivated infective larvae was unsuccessful.
 
Article
The cuticle forming the excretory pore complex and the vulva and vagina vera in female Syphacia obvelata is formed by body wall cuticle. The nature of the cuticle surrounding the excretory pore and forming the bladder, and tile absence of a muscular system to control the complex suggest that internal pressure (probably hydrostatic) is the generating force for fluid expulsion. The lumens of the vulva and vagina vera are lined by and continuous with the cortical zone of the body wall cuticle. The lumens of both the vulva and vagina vera are tetraradiate. The arrangement of the cuticle at the proximal end of the vagina vera allows for a mechanical means of ejecting eggs (the functional ovijector). The initial force to move eggs up to the ovijector is from the muscles surrounding the vagina vera.
 
Article
A postlarva of the trypanorhynch, Hepatoxylon trichiuri (Holden 1802), was discovered in the caecum of the giant squid, Architeuthis dux Steenstrup 1857. This may establish a selachian or a teleost as being food of the architeuthid, about which subject there is no direct information.
 
Article
The head region of the pinworm Syphacia obvelata (Rudolphi, 1802) has been examined to determine the nature of modification of the cuticle responsible for, or associated with, lips and buccal capsule, cephalic papillae and amphids, cephalic inflations, and cervical alae. The median zone of the cuticle was found to be the most modified and variation in the extent and distribution of striated material is compatible with its proposed structural role. The variations found are probably related to compensation for stresses that may develop in the cuticle during the complex movements of the head end. Lips are only inconspicuous expansions of the body wall cuticle, while esophageal cuticle is strikingly different in appearance. It is proposed to refer to all regions of the mouth cavity bounded by both the lips and esophagus as the buccal capsule while only the limited region bounded by body wall cuticle may be referred to as stoma. A mechanism involving three groups of intrahypodermal cytoskeletal filaments attached to the tips of somatic muscles, esophagus, and cuticle is proposed to move the lips.
 
Article
The body cuticle of Syphacia obvelata (Rudolphi, 1802) has been examined with light and electron microscopy through larval and adult stages. In all stages the cuticle consists of a cortex, and median and basal zones. Material showing transverse striations with 180–220 Å periodicity (striated material) occurs in the median zone of larvae and young adults. However, progressive growth and deposition of more striated material results in the cuticle of older females appearing markedly different from the cuticle of the short-lived males. Striated material is concluded to be formed of bands of approximately circular discs. Overlap of such bands produces the various patterns seen in sections. Similarities between methods of formation of striated material and other cuticular components are noted between molting periods and the growth phase of females. The presence of intracuticular tubules and external longitudinal ridges is noted.
 
Article
Ten species of freshwater ostracods were ingested by Catostomus commersoni. Of these Physocypria pustulosa females were recovered alive from the gut and were able to reproduce. The possible significance of this observation to P. pustulosa dispersal is discussed.
 
Article
Dicrocoelium dendriticum is reported for the first time in western Canada. Nearly 4000 worms were obtained from the bile ducts of two British Columbia cattle slaughtered in Lethbridge, Alberta in April, 1973. On the basis of unpublished records, it appears that D. dendriticum occurs in three localities in British Columbia, and has been known since 1965.
 
Article
In the Delta Marsh, third-stage Echinuria uncinata juveniles were found in Daphnia magna, D. pulex, Simocephalus vetulus, and Gammarus lacustris. Daphnia magna, the major host, were found infected from late May to early November with a peak of 108 parasites per 100 Daphnia in early August. Experimentally, D. magna, D. pulex, Ceriodaphnia reticulata, C. acanthina, S. vetulus, Moina macrocopa, Eurycercus lamellatus, G. lacustris, Hyallela azteca, Chirocephalopsis bundyi, and Lynceus brachyurus became infected when exposed to E. uncinata eggs. Parasites developed to the infective stage in D. magna and D. pulex in 30 days at 15 °C and in 10 days at 20–24 °C.In mallard ducks, E. uncinata completed the fourth molt 20 days after infection; male worms were sexually mature after 30 days and females oviposited 40 days after infection. Parasites grew faster in 1-week-old Delta mallards than in 2- and 3-month-old birds. Adult nematodes were located beneath the mucosal layer at the junction of the proventriculus and gizzard where granulomas formed after 30 days. The number of granulomas was correlated with the number of parasites. Mallards, pintails, gadwalls, lesser scaup, common eiders, and domestic geese were more susceptible to Echinuria infection than were shovellers, blue-winged teal, redheads, ruddy ducks, and American coots. Parasite eggs died when frozen but 50% survived 85 days when dried on filter paper. Echinuria uncinata can survive winter in resident mallards.
 
Article
A gubernaculum is demonstrated in the male Ascarops strongylina (Rudolphi, 1819) by examination of serial sections of the caudal region. Mature specimens of A. strongylina were found in a bird, a greater sulphur-crested cockatoo, Cacatua galerita.
 
Article
The incidence of abnormalities or structural deformities in the squid Illex illecebrosus was extremely low for the sample number (595) examined. The anomalies found were of five types; (1) brachial anomalies which involve sucker displacement, (2) abnormal ctenidia, involving deformities of associated vascular organs, (3) abnormal mantle-hyponomal locking cartilages, (4) dextral displacement of the caecum with respect to the location of the stomach, and (5) duplication of the chitinous lining of the alimentary canal.
 
Article
The alimentary tracts of seven Weddell seals taken at McMurdo Sound, Antarctica, were examined for helminth parasites. Two species of trematodes, three of cestodes, and one of nematodes were recovered. Numerical data on incidence and intensity of infection are given for each species. Heavy infections of diphyllobothriid plerocercoids were also recorded.
 
Article
Five species of the subgenus Gyrodactylus (Mesonephrotus) Malmberg, 1964, namely G. stunkardi Kritsky and Mizelle, 1968, G. freemani n. sp., G. prolongis Hargis, 1955, G. atratuli Putz and Hoffman, 1963, G. avalonia Hanek and Threlfall, 1969, and seven species of the subgenus Gyrodactylus (Metanephrotus) Malmberg, 1964, namely Gyrodactylus etheostomae Wellborn and Rogers, 1967, G. eucaliae Ikezaki and Hoffman, 1957, G. macrochiri Hoffman and Putz, 1964, G. goerani n. sp., G. limi Wood and Mizelle, 1957, G. nebulosus Kritsky and Mizelle, 1968, and G. dechtiari n. sp., are described and figured from the fishes of the Bay of Quinte region, Ontario.
 
Article
In this fourth and final paper on the monogenetic trematodes from the Bay of Quinte area, Ontario, the genus Dactylogyrus Diesing, 1850 is studied. Host–parasite and the parasite–host lists of the monogenetic trematodes recovered during the entire survey are presented.
 
Article
Examination of 129 bobcats (Lynx rufus) from New Brunswick, Nova Scotia, and Maine and 14 lynx (Lynx canadensis) from Newfoundland revealed the presence of adult Taenia macrocystis (Diesing 1850) in 86% of the bobcats and in all the lynx. Concurrent examination of snowshoe hares (Lepus americanus) showed that a high proportion of adult hares were infected with cestode larvae of the strobilocercus type. Scolices of these larvae were identical with scolices of T. macrocystis adults recovered from wild cats.Experimental infection of domestic cats with fresh larvae from hares yielded adult taeniids, within 42 days, which were identical with the adult T. macrocystis found in wild cats.Experimental infection of laboratory-reared snowshoe hares with eggs of these cestodes produced fully developed, infective strobilocercus larvae within 14 weeks, thus establishing that Lepus americanus acts as an intermediate host in the life cycle of T. macrocystis in northeastern North America.
 
Article
Two hundred and fifty auks of five species (Alca torda, Uria aalge, Uria lomvia, Cepphus grylle, Fratercula arctica) were collected in Newfoundland in 1972 and 1973, and examined for Ixodes uriae. Ticks were recovered from all the bird species examined except C. grylle. No significant difference (P > 0.05) was found in the burden on adult auks with regard to sex and weight. The distribution of the tick stages on the hosts is presented: adult females prefer the neck, larvae prefer the body regions. The distribution of nymphs varied with the host species. The population structure of the tick on the hosts is recorded. Immature auks are rarely infested.
 
Top-cited authors
Bradley White
  • Trent University
Peter T Boag
  • Queen's University
Ian Stirling
  • University of Alberta and Environment and Climate Change Canada
Marco Festa-Bianchet
  • Université de Sherbrooke
Brock Fenton
  • The University of Western Ontario