Showing papers in "Journal of Zoology in 1958"

The green sea turtle, chelonia mydas (linn.) in malaya and sarawak

Abstract: SUMMARY A four-year study was conducted on breeding populations of Green Sea Turtles, Chelonia mydas (Linn.), in Malaya and Sarawak. The area of study was confined to the South China Sea (Sunda Shelf) coasts of the two countries. The history of the exploitation of sea turtle populations for eggs in the Muslim areas of Malaysia is reviewed; compared with other parts of the world where turtles are killed for flesh and fat, the populations in Malaya and Sarawak appear to have suffered little reduction in size. The general aspects of the marine environment and the different types of sea turtle breeding beaches in the area are described. Chelonia mydas tends to build up large breeding concentrations around a small number of beaches, with only limited use of other beaches in the region. Possible causes and adaptive features of the observed situation are discussed. The type of beach utilised by large breeding concentrations of Green Turtles is described, and several particular beaches are described in detail. The process of nesting is described at length, drawing on extensive field notes made over a four-year period. Particular attention is paid to behavioural aspects of the nesting process and to their possible adaptive significance. Female turtles approaching the beach for nesting are very shy while still in the water and still able to make a rapid escape; they show a clear set of reactions to visual stimuli. With progression up onto the land and isolation from the aquatic environment, the turtles show progressively less response to alarm stimuli. Ihe mechanics of terrestrial locomotion and of the various nesting activities are described, along with discussions of inhibitory and initiatory stimuli which appear to govern the different stages in the process. A table is presented showing the timing of the nesting process in three selected observations on individual females. Courtship and copulation in Chelonia mydas are described as they were observed in Malaya and Sarawak. 2,720 adult female turtles were tagged on three islands off Sarawak, where the Sarawak Government operates a turtle egg industry. Through the cooperation of the industry, statistical studies were carried out. Methods of tagging are described and pertinent features of the statistical work are discussed The recorded annual egg production from the three islands averages slightly less than two million eggs a year, with a recorded minimum of 700,000 and a maximum in excess of three million eggs. While there is no non-breeding season in Sarawak, there is a pronounced annual cyclical variation in the intensity of breeding, with a marked heavy season around June, July, and August. The absence of a non-breeding season is considered to be related to the virtual lack of any marked annual variation in temperature. The existence of a definite peak breeding season is thought to relate to the adaptive advantage of a habit of synchronous breeding aggregation in a widely ranging species. The timing of the peak breeding season appears to relate to the period of the Northeast Monsoon, which brings relatively inclement weather from November through February. The development and decline of the breeding season as shown by egg production figures from the industry shows a remarkable consistency through “good” years and “bad”. While presumably located in time to occur when monsoon effects are minimal, it does not show correspondence to yearly fluctuations in the timing of the monsoon. The per cent contribution of each calendar month to the annual total egg production tends to remain constant regardless of whether the monsoon periods preceding or following are early or late. Individual tagged turtles returned repeatedly to the same beach to nest. Of 5,748 records of returning tagged females only 3–7 per cent failed to return to the same island previously used, despite the fact that two of the islands were only about 500 metres apart. Female turtles nested six or seven times in a season at intervals of about 10 days. Records showed a maximum of 11 successful nests made by a single individual. 8,147 clutches of eggs averaged 104-7 eggs per clutch, with a Standard Deviation of 1–31. The return in 1956 of numbers of the turtles tagged in 1953 indicates a three-year breeding cycle in the Sarawak turtles, and provides evidence that individuals are able to make their way back to the same nesting grounds after the long absence. The environment of the incubating nest is described and the hatchery procedures practised on the Sarawak islands are outlined. A special series of nests was transplanted to the industry's hatchery enclosure for studies on incubation. Although surface sand temperatures underwent a diurnal fluctuation of as much as 23o C, at the depths where eggs were deposited the measured temperature never fluctuated more than about 2o C. Incubating nests showed a progressive temperature rise due to the metabolic heat produced by the developing embryos, reaching temperatures as high as 35o C. by the time of hatching. Records of 354 hatchery nests showed an average of 47 per cent of the transplanted eggs resulting in hatchlings which emerged to the surface. Recorded intervals between oviposition and time of emergence of young turtles to the surface varied seasonally from an average of about 70 days during the latter part of February to an average of about 54 days during the period June to October. The process of emergence of the hatchling turtles from their subterranean chamber and their movement to the sea is described. The available data on growth rate and age of maturation is assembled and discussed. It is concluded that Asian Green Turtles probably mature in from four to six years. The carapace measurements of 200 adult females from Sarawak are plotted on a graph; the weights and carapace measurements of ten females are given in a table. Predation upon incubating nests and upon turtles at all stages is discussed. Ghost Crabs (Ocypoda sp.) were the most serious observed menace to incubating nests in the areas studied. The heaviest predation observed on hatchling turtles was by Ghost Crabs and small sharks. There is little predation by sea birds on the Malaysian beaches. Several large Tiger Sharks (Galeocerdo sp.) were caught off the Sarawak islands; two of these had the remains of adult sea turtles in their stomachs. The various parasites and commensals found on turtles during the study are reported; observations are made on the burrowing parasitic barnacle, Stephanolepas muricata, and its apparent tumour-inducing proclivities. The paper concludes with an analysis of the problem of scientific management of wild populations of Green Turtles. It is concluded that exploitation for eggs is more logical, more profitable, and more amenable to management techniques than is exploitation for flesh and fat.

The behaviour of the giraffe, giraffa camelopardalis, in the eastern transvaal

Abstract: SUMMARY The giraffe in South Africa live entirely in the Eastern Transvaal, a lowveld region primarily of grass or veld with scattered bushes and low trees. The giraffe browse on a wide variety of trees in the spring and fall when few leaves are available, but in summer when all the trees are in foliage they are much more selective. The giraffe spend most of the day and part of the night feeding, especially the early morning and late afternoon. In the summer when food is abundant, the giraffe have more time during the day to chew their cud and lie down. The males spend part of the day fighting with each other. Such matches are seldom serious and often end in sexual play with one male mounting the other. The most common heterosexual activity was the testing of the females' urine by the male. There is no breeding season among giraffe, and the young are born all through the year. Giraffe are usually found in groups or herds, but they do not appear to communicate with each other, although they are capable of making sounds. The herds are loose associations of animals, generally with no definite leadership, and often include both adult males and females. Herds travelled very slowly, and often remained on the farm where they were studied for at least one year. The giraffe on Fleur de Lys farm have become used to farm conditions; they jump fences instead of breaking through them, and drink water from the cattle troughs, often walking among the cattle to do so.

The comparative ethology of grassfinches (erythrurae) and mannikins (amadinae)

Abstract: SUMMARY The behaviour of twenty-seven species of estrildine finches is concisely reported. Brief information is also given about the geographical distribution and the comparative morphology of the Estrildinae. Ethological, geographical and morphological data are then combined in a discussion of the evolution of the group, and finally some minor taxonomic revisions are suggested. Most of the ethological research has been concentrated on similarities and differences in sexual patterns, and the pre-copulatory behaviour of the following species is described: Zonaeginthus pictus (Painted Finch); Z. bellus (Fire-tail Finch); Z. guttutus (Diamond Sparrow); Poephila phueton (Crimson Finch); P. rujcuuda (Star Finch); P. guttutu (Zebra Finch); P. bichenovi (Bicheno Finch); P. modesta (Cherry Finch); P. cincta (Parson Finch); P. acuticuuda (Long-tailed Grassfinch); P. personata (Masked Grassfinch); P. gouldiae (Gouldian Finch); Erythrura spp. (Parrot Finches); Padda oryzivora (Java Sparrow); Amadina fasciatu (Cutthroat Finch); A. erythrocephala (Red-headed Finch); Lonchura pectoralis (Pectoral Finch); L. malabarica (Silverbill); L. bicolor (Black-breasted Mannikin); L. cucullata (Bronze Mannikin); L. striata (Striated Finch); L. punctulata (Spice Finch); L. ferruginosa (Chestnut Mannikin); L. maja (Pale-headed Mannikin); L. castaneothorax (Chestnut-breasted Mannikin); Estrilda temporalis (Red-browed Finch). Many of the sexual displays have been derived from nesting patterns, as a result of the intimate association in time of high intensity reproductive nest-building and high intensity courting. Straw-holding, bowing-with-straw, looping straw, mandibulating, tongueing, and cavity-scooping have been incorporated in the courtship sequences of many species and there are interesting specific differences in the ways in which these patterns have become modified as signals (i.e. ritualised). Displacement beak-wiping is also an important source of ritualised signals' in various species; here too there are specific differences in the extent and nature of the ritualisation. The vertical inverted curtsey dance and the horizontal pivoting dance of the males are derived from intention movements of approaching and avoiding the female. Certain pair-formation ceremonies are shown to be related to sunbathing patterns. The evolution of the group appears to have taken one of the following two possible courses: The group seems to have originated in Africa and from there to have spread around the Old World to Australia via Asia. This probably involved ancestoral mannikin forms, which gave rise to the grassfinches when they reached Australia. Many of the grassfinches are now extremely convergent with certain African waxbills. The alternative evolutionary scheme, which cannot be ruled out on the present evidence, is that both ancestoral mannikins and waxbills spread round to Australia and that the grassfinch group is not a natural unit, but that part of it has come from ancestoral mannikin stock and part from ancestoral waxbill stock. The former view is favoured here, but it is stressed that more information is required to be certain on this point. In conclusion, a taxonomic revision is presented, as far as the species discussed here are concerned. This involves the following changes to Delacour's (1943) arrangement: the setting up of three more subgenera (Spermestes; Gouldaeornis; Aegintha) and two more genera (Aidemosyne; Bathilda); the shifting of the Red-browed Finch from the waxbill tribe to the grassfinch tribe, and several other minor alterations. No new names are introduced; in each case an old name discarded by Delacour has been revived. Delacour's revision of the group was extremely valuable in sweeping away a mass of unnecessary “splitting”, but it over-compensated, and it is now necessary to reverse a few of his more extreme “lumpings”.

A revision of the british aceosejinae (acarina: mesostigmata)

Abstract: SUMMARY 1 This paper deals with a revision of the British species of the subfamily Aceosejinae together with a synonymic list of the species of the subfamily. 2 Keys are given for the separation of genera and species of the British aceosejines. 3 The following new synonymy is introduced: (a) Arctoseiulus Willmann and Arctotarseius Willmann are synonyms of Arctoseius Sig Thor. (b) Arctoseiodes Willmann is a synonym of Leioseius Berlese. (c) Seiopsis Berlese, Jordensia Oudemans and Blattilaelaps Womersley are synonyms of Proctolaelaps Berlese. (d) Garmania Nesbitt and Paragarmania Nesbitt are synonyms of Melichares Hering. (e) Arctoseiopsis Evans is a synonym of Iphidozercon Berlese. (f) Aceosejus Sellnick is a synonym of Lasioseius Berlese. (g) Lasioseius (L.)innumerabilis Berlese, Lasioseius alpinus Schweizer and Lasioseius ventritrichosus Schweizer are synonyms of Hypoaspis hypudaei Oudemans. (h) Typhlodromus domesticus Oudemans is a synonym of Melichares agilis Hering. (i) Typhlodromus tineivorus Oudemans, Blattisocius triodons Keegan and Lasioseius similis Schweizer are synonyms of Lasioseius (L.) tarsalis Berlese. (j) Lasioseius fimbriatus Halbert and Seiulus amboinensis Oudemans are synonyms of Lasioseius (L.) dentriticus Berlese. (k) Laelaps ligoniformis Michael is a synonym of Sejus muricatus C. L. Koch. (l) Arctoseius austriacus Willmann is a synonym of Gamasellus (Sessiluncus) eremitu Berlese.

The bottom fauna communities across the continental shelf off accra, ghana (gold coast)

Abstract: SUMMARY 1 A quantitative investigation of the marine bottom fauna has been earned out, in conjunction with an analysis of the physical environment, across the continental shelf off Accra from the shore to a depth of fifty fathoms. 2 The concept of “community” used in the present work is discussed and defined. 3 Although the nature of the bottom sediment is of primary importance, wave action in shallow water and temperature in deeper water are important factors in community differentiation. 4 Four distinct infaunal communities have been recognised associated with four different types of bottom conditions, these are: (a) The Inshore Fine Sand Community (0 to eight fathoms), dominated by the polychaetes Owenia fusiformis and Diopaira nea/polilana with the lamellibranch Cultellus tenuis. (b) The Sandy Silt Community (8–20 fathoms), with Turritdla annvMa and Sternaspis scutata. (c) The Silty Sand Community (20–25 fathoms), dominated by two species of Foraminifera–Jullienellajoetida and Schizammina sp. (d) The Coarse Sand Community (25–50 fathoms), dominated by the coral Caryophyllia clavus. 5 At depths greater than fifty fathoms a rock epifauna exists which is Mediterranean in nature and contains many new faunal records for West Africa. It is characterised by massive colonies of the coral Dendrophyllia ramea and large numbers of the basket star Astrospartus mediterraneus. The bottom temperature at this depth varies little from similar depths in Northwest Africa and the Mediterranean. 6 The communities off Accra are clear cut and well defined and this is considered to be largely due to the rapidly changing nature of the bottom deposits across the shelf. These rapid changes in bottom conditions are caused first of all, in shallow water, by the sorting action of the surf waves on the bottom deposits. In deeper water a second transition is brought about by the production of coarse sediment from the erosion of a limestone deposit on the outer shelf edge.

Reproduction in the east african lung-fish protopterus aethiopicus heckel

Abstract: SUMMARY 1Four occupied nests, which differ in form and environment, of P. aethiopicus are described from Lake Victoria. These constitute the first definite records of the nests of this species. Evidence is adduced which strengthens the possibility that certain structures previously thought by other authors to be nests were in fact those of lung-fishes. 2The oxygen content of one nest was determined and found to be low, probably never exceeding 3 p.p.m. During the breeding periods studied, the modal day water temperature was 23oC. and the temperature range 17-8o to 25-0oC. The least diurnal temperature variation was 0–5o and the greatest 3–6oC. 3From one nest over 5,000 larvae were recovered and from another (incompletely sampled) more than 2,000. Some broods showed a distinct fractioning into several ontogenetic stages. It is concluded that fractioning is attributable to slight initial differences in the time of fertilization and reinforced by individual variation in developmental rates. The scanty data available suggest that more than one female spawns in a nest. 4Larval P. aethiopicus begin air-breathing when they have reached a length of 23 to 25 mm. It seems probable that whilst the larvae remain in the nest they are not dependent on aerial respiration. 5In its external features, the embryology of P. aethiopicus closely resembles that of P. annectens. Slight differences in ontogeny are discussed. The ova, embryos and larvae of P. aethiopicus are larger than those of P. annectens, and have a slower- developmental rate. Also, the larvae attain a larger size before the yolk is fully resorbed. 6At ca 23oC. young P. aethiopicus remain in the nest for fifty to fifty-five days. Pre-hatching development takes about fifteen days; thereafter the young grow to a length of ca 35 mm. in forty days. 7Post larval P. aethiopicus live actively in the matted papyrus roots and the root systems of swamp grasses. There is no evidence to support an earlier idea that they pass the first year of life in a quiescent condition. 8The external gills are ciliated. Data relating to the development and subsequent necrosis of these gills is reviewed and summarized. 9The breeding cycles of P. aethiopicus in Lake Victoria are imperfectly known. Observations made on ovarian conditions indicate a peak breeding season from November to April. Occupied nests were found in this period, and in September. This latter nest suggests that spawning may also occur during unseasonal. wet periods.

The anatomy and physiology of the reproductive system of the freshwater snail physa fontinalis (l.)

Abstract: SUMMARY Physa fontinalis is a hermaphrodite gastropod in which the gametes formed in the ovotestis pass down the common hermaphrodite duct to the albumen gland, where the male and female systems separate. The spermatozoa are carried down the vas deferens to the penis and are introduced into the bursa copulatrix of the copulatory partner, whilst the eggs, after fertilisation, pass through the oviduct, where they receive the mucous coverings which form the egg capsule. The morphology and histology of the reproductive system of P. fontinalis have been described, together with an account of the role of each of the genital organs. When mature, the spermatozoa are liberated from the ovotestis and are stored in the hermaphrodite duct, whereas, the eggs are released only immediately before oviposition and pass through the mass of male gametes. It is suggested that the muscle sheath which surrounds the junction of the hermaphrodite duct, vas deferens and oviduct constitutes a regulating mechanism, directing the ova and the majority of the spermatozoa into their correct channels. The vas deferens is a ciliated, non-glandular duct, but the semen receives secretory additions formed by the prostate follicles, the glandular products being driven out of these diverticula by the action of small, interstitial, ciliated cells. During the breeding season, the characteristic, glandular cells in the penis sheath and praeputial gland become greatly swollen and secrete mucopolysaccharides which probably facilitate the eversion of the penis. The female duct is composed of a glandular oviduct and muscular vagina, the former being divisible into three regions. The bursa copulatrix serves as a receptacle for foreign sperm and its duct opens into the vagina. Unlike the representatives of the other families of the Hygrophila which have been studied, a true albumen gland duct is missing and the ova pass into the albumen gland before entering the oviduct. In P. fontinalis fertilisation occurs in the lower part of the hermaphrodite duct and not in the “fertilisation pockets”. It appears that the animal is largely self-fertilising, but it is suggested that after several generations have been produced by this means, a physiological barrier to the animal's own sperm is developed, so permitting fertilisation by foreign sperm. The albumen gland secretes galactogen and, after fertilisation, the ova enter this organ to receive a coating of its nutritive secretion. As the eggs pass down the oviduct, they are surrounded by the mucous envelopes which constitute the egg capsule, each portion of the duct having a separate function in the formation of the different investments.

The multimammate mouse rattus (mastomys) natalensis smith: a laboratory‐adapted african wild rodent

Abstract: SUMMARY 1 Laboratory-breeding stocks of the multimammate mouse, Rattua (Mastomys) natalensis, have been maintained since 1939 and have become of increasing importance in medical research. This mouse has been used primarily as the standard test-animal in routine diagnostic and experimental work in plague. 2 It is highly susceptible to experimental infection with Schistosoma mansoni, and in consequence has assumed importance in bilharzia research. 3 A high proportion (30 to 50 per cent) of animals dying in the colony from natural causes have been found to be suffering from spontaneous adenocarcinoma of the glandular stomach—a condition which is extremely rare in animals other than man. The multimammate mouse promises to be an impor tant experimental animal in cancer research. 4 The taxonomic status of the multimammate mouse has not been satis factorily defined. Some of its anatomical and physiological features are Rattus—like, others Mus—like, while others appear to be unique (e.g. the presence of a prostate gland in the female). 5 The known similarities and differences between the multimammate mouse, the laboratory rat and the laboratory mouse are tabulated. On the available data it is hard to say whether it should be classified as a subgenus of Rattus, as it is at present, or whether Mastomys should be given generic rank or made a subgenus of Mus.

The systematic position of browneichth ys ornatus woodward (pisces, actinoptergii)

Abstract: SUMMARY The unique holotype of Browneichthys ornatus Woodward has been reexamined. Illustrations of the specimen are published for the first time, and, although it has not been possible to add considerably to the text of the original account, a short redescription is included. The systematic position of Browneichthys ornatus is discussed. It is concluded that this species should not be retained in the family Saurichthyidae and its transfer to the family Coccolepidae is proposed.