The biology of Australian reef populations of the shark Heterodontus portusjacksoni has been studied underwater with SCUBA. Additional life—history data have been obtained from catch records of adults and juveniles and from observations on captive animals. The mature breeding female H. portusjacksoni lays 10—16 eggs which are deposited in rock fissures on shallow reefs; the young emerge approximately 1 year later. The breeding season on the central coast of New South Wales occurs in late winter and spring. This species appears to segregate by sex into separate juvenile, adolescent, and adult populations. A slow growth rate and protracted immaturity is characteristic. Sexual maturity is reached at 8—10 years for males and 11—14 years for females. Most feeding occurs during darkness over both reefs and soft substrates, gut contents reveal that they feed on a variety of benthic invertebrates. Populations of H. portusjacksoni observed on sublittoral reefs consisted of adult sharks, the majority of which were females. A few specific sites, usually caves in which they shelter during the day, are preferred. Resightings of sharks tagged on a reef at Bondi, Sydney, revealed that animals which formed the local population moved freely to and from the reef and also between the several sites on the reef. Reef densities were highest during the breeding season and were correlated with low water temperatures. Emigration from inshore reefs occurs at the end of the breeding season in late September and October. A number of tagged sharks returned to the same reef in the following year and others after periods of up to 2 years. Recaptures made outside the Sydney area indicate that some sharks may travel several hundred kilometers during their migration.
SummaryThe results of over 1400 precipitin tests on the stomach contents of engorged mosquitoes to determine the source of their blood meals are recorded. Fifteen species of mosquitoes are included in this survey, but three .species, Anopheles annulipes, Culex fatigans, and C. annulirostris, dominated the collections.Engorged mosquitoes have been collected from three types of situation. (i) Restricted animal habitats such as human dwellings, fowl houses, horse stables, dog kennels, and rabbit warrens; (ii) The general farmyard environment; and (iii) River Hats and creek banks.The collections from restricted animal habitats have indicated that for the species under consideration the site of collection is indicative of the blood source of the mosquitoes therein collected. Farmyard collections have given valuable information on the range of hosts attacked by nocturnally active mosquitoes. River Hat collections have been most useful in disclosing rabbitfeeding species. Collections have also been made of mosquitoes attracted to man in the field and a small but significant percentage of these have been found to be already engorged. Such collections have been most interesting in that species feeding on marsupials have been revealed.To the information derived from these precipitin tests has been added our accumulated observations of biting activity in the field, on man and other animals. In this way it has been possible to prepare a statement of the range of blood sources known to be utilized by each species and to give some indication of the preferences exhibited by certain mosquitoes for particular blood sources.Anopheles annulipes has been shown to feed particularly on cattle and rabbits although other animals, man, and poultry are also attacked. Culex fatigans bites man in the domestic environment but is equally attracted by fowls in fowl-runs, or by horses in stables or dogs in kennels. Biting by this species is almost exclusively under shelter. C. annulirostris attacks man and most domestic animals but is most active out of doors. Rabbits are frequently attacked by this species. It is well known as biting man but man is not a preferred blood source. Culex pipiens australicus has been shown to attack rabbits and poultry. Species which have been revealed as attacking marsupials are Anopheles stigmaticus, Aedes notoscriptus, A. alboannulatus, and A. queenslandis. Finally the significance of the feeding habits is discussed in relation to possible disease transmission by the various species. Anopheles annulipes, Culex annulirostris, and C. pipiens australicus, because of the frequency with which they attack rabbits, have an important role in myxomatosis transmission. Culex fatigans and C. annulirostris, attacking both poultry and man, are likely suspects for the transmission to man of Murray Valley encephalitis. Anopheles annulipes, on the other hand, because it attacks man only casually, is unlikely to assume any importance as a vector
SCUBA observations show that Port Jackson sharks repeatedly visit specific resting sites on ocean reefs at South Bondi (New South Wales) and, when disturbed, move directly from one site to another. The sharks also use specific resting sites in Sydney Harbour and, when transferred by boat to different localities within the harbour, up to 3 km away, return to their original resting sites. The sharks migrate from as far south as Tasmania to Sydney Harbour to lay their eggs in specific sites. Speculative extrapolation from the above observations suggests that Port Jackson sharks must have a highly developed spatial memory.
The rate of ciigesl;iol1 of human blood was invcsLigated at 4-hourly intorval" by tho I'reeipitin and benzidine tests for tho mosquito species .Aedes aegypti, A. concolor, A. noto8oriptu8, A. soutellaris, and Culea., fllliymis. In an enviroWllent ill which temperature and humidity w('["o oonstant and in whioh thoro were equal periods of light and darkness, the mie of digestion ranged from :11 hI' for 8CUtellm'is to ·Hl hI' for A. COil color.
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