Seasonal variation in septal spacing of Sepia officinalis and some Ordovician actinocerid nautiloids

Studies of cuttlebone of Sepia officinalis L. from the English Channel show a direct and linear correlation between ambient water temperature and septal spacing. The application of this observation to fossil shallow-water nautiloids and ammonoids is complicated by the equatorial habitat of many of these shells, their declining rate of chamber production through ontogeny and a paucity of large and complete specimens. But annual temperature variations are the most likely cause of variations in septal spacing a priori , temperature apparently being the prime determinant of feeding and growth rates of individuals at a particular ontogenetic stage. ▭ Nautiloids, annual growth, Ordovician , Sepia, English Channel.     

Incubation temperature in the Australasian Gannet Moms senator

Gannets (Sulidae) and some other pelecaniforms incubate their eggs under the webs of their totipalmate feet. These species have a wide latitudinal distribution from tropics to subarctic, but little is known of the incubation temperatures attained. I measured egg temperatures of the Australasian Gannet Morns serrator at Cape Kidnappers, New Zealand, employing a data logger to obtain records every 15 min for day-long sample periods at undisturbed nests. Egg surface temperatures were relatively stable and little affected by ambient temperature. Mean surface temperature of natural eggs was 34.9^oC for samples taken during the first 4 days of incubation, but this then increased and stabilized at 36.5^oC. Internal temperature of pipped eggs was about 1^oC higher, attributable to embryonic heat production. Upper surface temperature of eggs kept in a fixed position was about 2^oC below deep adult body temperature (40.3^oC), suggesting heat is transferred directly from the body through the feet. Clutch size does not appear to be limited by an inability to warm two eggs. These results are in general agreement with measurements from other web incubators and are well within the range for species with conventional brood patch incubation.     

Flying and walking of small insects (Musca domestica) recorded differentially with a standing-wave radar actograph

ABSTRACT. An actograph is described for recording the behaviour of small insects, by using a standing-wave radar system in an enclosed metal cabinet. Experiments show that the system produces an output frequency dependent only on the speed of movement of the subject. By filtering the signal electrically into components below and above 5 Hz, walking and flying of adult Musca domestica could be separately recorded. Each filter is followed by a level-comparator with hysteresis. Activity causing signal to cross the hysteresis-band is recorded as an event on a digital counter, and also integrated or summed to be displayed as a stepped-integral or bar-chart of total distance covered by the subject in each counting period. The energy-density of the radar can be kept very low, so that possible influence on the subject is minimal. The detector is remote from the box containing the subject, giving great flexibility in container design, so that the apparatus is ideally suited to the study of environmental factors.     

Food niches of sympatric Marsh Harriers Circus aeruginosas and Hen Harriers C. cyaneus on the Dutch coast in winter

Analysis of pellets collected from adjacent communal winter roosts of Marsh Harriers Circus aeruginosus and Hen Harriers C. cyaneus on an extensive saltmarsh in the southwest Netherlands showed highly significant differences between the diets of the two species. Marsh Harrier diet showed no change throughout January, February and March. They specialized on ducks, which were about half of their prey numerically and more important by weight. Although Marsh Harriers sampled other prey, this remained at a low level and showed no seasonal response to the availability of young lagomorphs. Hen Harriers occupied the niche of a generalist predator, having a broader diet and responding to the presumed changes in availability of prey with diet shifts. In November, about half of their prey items were passerines but these declined in importance in December, and small mammals rose. The proportions of both small mammals and birds fell in February and March, due to increasing dependence on young lagomorphs. Diet overlap between the two species was greatest in January and declined in February and March.     

Low Temperature Treatment of Barley Plants causes Altered Gene Expression in Shoot Meristems

We have examined whether acclimation to cold may involve alteredgene expression by testing for the appearance of new mRNA, capableof in vitro translation, in shoot meristems of the temperatecereal, barley, grown at 6 ?C day/2? C night. New mRNA is foundafter only 2 d in the cold, when acclimation is detectable butnot complete. The altered pattern of gene expression persistsduring subsequent growth in the cold and is associated witha number of new mRNA molecules including a major mRNA whichencodes a polypeptide Mt 77000. Key words: Hordeum vulgare cv. Igri (barley), low temperature, acclimation, gene expression     

Scaling of Cardiovascular Physiology in Snakes

The elongate body form of snakes and the wide diversity of habitatsinto which they have radiated have affected the form and functionof the cardiovascular system. Heart position is strongly correlatedwith habitat. The heart is located 15–25% of the bodylength from the head in terrestrial and arboreal species, but25–45% in totally aquatic species. Semi-aquatic and fossorialspecies are intermediate. The viperids are exceptional, withgenerally more posterior hearts but arboreal species have heartscloser to the head. An anterior heartis favored when snakesclimb because it reduces the hydrostatic pressure of the bloodcolumn above the heart and tends to stabilize cephalic bloodpressure. In water, where hydrostatic bloodpressure is not aproblem, a more centrally located heart is favored because theheart does less work perfusing the body. In terrestrial species,head-heart distance increases linearly with body length andthe increased hydrostatic pressure is matched by higher restingarterial blood pressure in longer animals. Unlike mammals andbirds, snakes have blood pressures that increasewith body mass.The added stress on the ventricle wall in larger snakes is correlatedwith ventricles that are larger than predicted by other reptiles.Heart mass scales with body mass to the 0.95 power in snakesbut only 0.77–0.91 in other reptiles that are not as subjectto the hydrostatic effects of gravity. The spongy hearts ofreptiles do not conform well to the Principle of Laplace.     

Generic classification of the fern flies (Diptera: Teratomyzidae) with a larval description

Abstract. The seven recognized genera of Teratomyzidae, including the new genera Stepta, Auster, Pous, Camur and Lips , are keyed and described. Vitila is a new subgenus of Teratomyza Malloch. The following five new species are described: Auster pteridii (Australia), Pous manicula (Australia), Camur willii (Brazil), Lips collessi (Australia), Teratomyza ( Vitila ) undulata (Australia). Stepta latipennis is a new combination for Teratomyza latipennis Malloch. Neogeomyza Séguy, 1938 ( Micropachycerina Stuckenberg, 1971, syn.n.) belongs in the Lauxaniidae, not Teratomyzidae. Neogeomyza stenoptera (Stuckenberg, 1971 (from Micropachycerina ) is a new combination. The family Teratomyzidae occurs in the Neotropical, Australasian, Oriental and eastern Palaearctic Regions. The third-instar larva and puparium of Auster pteridii , both of which live externally on fronds of Pteridium (Filicales: Dennstaedtiaceae), are described. Adults of many species also occur on fern fronds.