Diving behaviour, dive cycles and aerobic dive limit in the platypus Ornithorhynchus anatinus

We investigated the diving behaviour, the time allocation of the dive cycle and the behavioural aerobic dive limit (ADL) of platypuses (Ornithorhynchus anatinus) living at a sub-alpine Tasmanian lake. Individual platypuses were equipped with combined data logger-transmitter packages measuring dive depth. Mean dive duration was 31.3 s with 72% of all dives lasting between 18 and 40 s. Mean surface duration was 10.1 s. Mean dive depth was 1.28 m with a maximum of 8.77 m. Platypuses performed up to 1600 dives per foraging trip with a mean of 75 dives per hour. ADL was estimated by consideration of post-dive surface intervals vs. dive durations. Only 15% of all dives were found to exceed the estimated ADL of 40 s, indicating mainly aerobic diving in the species. Foraging platypuses followed a model of optimised recovery time, the optimal breathing theory. Total bottom duration or total foraging duration per day is proposed as a useful indicator of foraging efficiency and hence habitat quality in the species.     

The influence of preceding dive cycles on the foraging decisions of Antarctic fur seals

The foraging strategy of many animals is thought to be determined by their past experiences. However, few empirical studies have investigated whether this is true in diving animals. We recorded three-dimensional movements and mouth-opening events from three Antarctic fur seals during their foraging trips to examine how they adapt their behaviour based on past experience—continuing to search for prey in the same area or moving to search in a different place. Each dive cycle was divided into a transit phase and a feeding phase. The linear horizontal distance travelled after feeding phases in each dive was affected by the mouth-opening rate during the previous 244 s, which typically covered two to three dive cycles. The linear distance travelled tended to be shorter when the mouth-opening rate in the previous 244 s was higher, i.e. seals tended to stay in the same areas with high prey-encounter rates. These results indicate that Antarctic fur seals follow decision-making strategies based on the past foraging experience over time periods longer than the immediately preceding dive.     

Cormorants dive through the Polar night

Most seabirds are visual hunters and are thus strongly affected by light levels. Dependence on vision should be problematic for species wintering at high latitudes, as they face very low light levels for extended periods during the Polar night. We examined the foraging rhythms of male great cormorants (Phalacrocorax carbo) wintering north of the Polar circle in West Greenland, conducting the first year-round recordings of the diving activity in a seabird wintering at high latitudes. Dive depth data revealed that birds dived every day during the Arctic winter and did not adjust their foraging rhythms to varying day length. Therefore, a significant proportion of the dive bouts were conducted in the dark (less than 1 lux) during the Polar night. Our study underlines the stunning adaptability of great cormorants and raises questions about the capacity of diving birds to use non-visual cues to target fish.     

Surfacers change their dive tactics depending on the aim of the dive: evidence from simultaneous measurements of breaths and energy expenditure

Air-breathing divers are assumed to have evolved to apportion their time between surface and underwater periods to maximize the benefit gained from diving activities. However, whether they change their time allocation depending on the aim of the dive is still unknown. This may be particularly crucial for ‘surfacers’ because they dive for various purposes in addition to foraging. In this study, we counted breath events at the surface and estimated oxygen consumption during resting, foraging and other dives in 11 green turtles (Chelonia mydas) in the wild. Breath events were counted by a head-mounted acceleration logger or direct observation based on an animal-borne video logger, and oxygen consumption was estimated by measuring overall dynamic body acceleration. Our results indicate that green turtles maximized their submerged time, following this with five to seven breaths to replenish oxygen for resting dives. However, they changed their dive tactic during foraging and other dives; they surfaced without depleting their estimated stores of oxygen, followed by only a few breaths for effective foraging and locomotion. These dichotomous surfacing tactics would be the result of behavioural modifications by turtles depending on the aim of each dive.     

Purification and characterization of ostrich prothrombin

The work focused on the penultimate enzyme, prothrombin, in the coagulation cascade. Prothrombin was purified and characterized from ostrich plasma. The results obtained contribute to a better understanding of blood coagulation in the ostrich and the evolution of prothrombin and the coagulation cascade. Prothrombin was purified from ostrich plasma by barium chloride precipitation, ammonium sulfate fractionation, and DEAE-cellulose and Cu(2+)-chelate Sepharose chromatography. Ostrich prothrombin exhibited a M(r) of 72,800 and a pI of 6.9 using SDS-PAGE and PAG-isoelectrofocusing, respectively. The N-terminal sequence of ostrich prothrombin showed 78 and 87% identity with human and bovine, respectively. The cDNA was isolated from ostrich liver and the predicted amino acid sequence compared with those from other species. Ostrich prothrombin shares sequence identity with chicken (84%), human (60%), bovine (59%), rat (60%), mouse (59%) and hagfish (50%) prothrombin, suggesting a common function of prothrombin in these vertebrates. Amino acid sequence identities indicate that the thrombin beta-chain (62%) and the propeptide-Gla (75%) domains are the regions most constrained for the common functions of vertebrate prothrombins. Ostrich prothrombin, therefore, shows similarity in structure to other vertebrate prothrombins.     

Purification and primary structure of ostrich insulin

Insulin has been isolated from ostrich pancreas by a procedure of acid ethanol extraction, adsorption onto SP-Sephadex, gel permeation chromatography and HPLC. The primary structure of the ostrich insulin is identical to that reported for the chicken hormone. The isoelectric point as determined by polyacrylamide gel isoelectric focusing was significantly higher than that of the bovine hormone.     

Depth utilization by Penguins and Gentoo Penguin dive patterns

Summary Time-at-depth data, recorded by animal-attached miniature depth gauges, were examined in 8 Gentoo Penguins. Birds showed two depth utiliuation patterns, (1) decreasing time with increasing depth, which we interpret as due to bounce-diving in the pelagic zone and (2) constant time per depth interval down to specific depths where large time peaks were encountered. We interprete this as flat-bottomed diving in benthic-foraging birds. Multiple maximum depth data reported in the literature for various penguin species were analysed to try and reconstruct proportional time-at-depth. These results, together with real time-at-depth data, indicated that penguin depth utilization was strongly mass dependent with larger species spending a greater proportion of time in deeper water.

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Die Tauchmuster des Eselpinguins und die räumliche Ausnutzung der Wassersäule durch Pinguine

Zusammenfassung Miniatur-Tiefenmeßgeräte wurden 8 Eselpinguinen angeheftet und die gewonnenen Daten der Aufenthaltsdauer in verschiedenen Wassertiefen untersucht. Die Vögel zeigten zwei Muster der Tiefenausnutzung, (1) abnehmende Aufenthaltsdauer mit zunehmender Wassertiefe, das wir als Stoßtauchen im Pelagial interpretieren und (2) konstante Aufenthaltsdauer pro Tiefenintervall bis in bestimmte Tiefen, in denen lange Verweildauer registriert wurden. Letzteres interpretieren wir als Grundtauchen bei Vögeln, die am Meeresboden nach Nahrung suchen. Aus der Literatur wurden multiple Tiefenmaxima für verschiedene Pinguinarten entnommen und analysiert, um die Aufenthaltsdauer pro Tiefenintervall zu rekonstruieren. Diese Ergebnisse zeigen zusammen mit tatsächlichen Meßdaten, daß die Tiefenausnutzung der Pinguine stark massenabhängig ist, wobei größere Arten eine größeren Zeitanteil in tieferem Wasser verbringen.

     

鸵鸟蛋皮串珠装饰品的发现与研究

鸵鸟蛋皮串珠从旧石器时代开始成为人类主要的装饰品类型之一,提供人类行为和认知发展方面的重要线索,至今仍广泛流行于非洲的狩猎采集者社会中,充当个人和群体间信息通讯的媒介。本文将从鸵鸟蛋皮的结构和种属鉴定入手,系统介绍旧石器时代鸵鸟蛋皮串珠的发现,及民族学记录中鸵鸟蛋皮串珠的制作与使用,并对20世纪以来有关鸵鸟蛋皮串珠的考古学研究作以概述,以期对我国考古学的相关研究提供有价值的信息与帮助。     

The optimal allocation of time and respiratory metabolism over the dive cycle

Because anaerobic metabolism is much less efficient than aerobicmetabolism in supplying energy, it is widely believed that diversrely predominantly on aerobic metabolism for diving. In thispaper, a time budget model, which assumes that the diver canuse either completely aerobic or partially aerobic metabolismwith additional anaerobic metabolism for diving, is developedand is used to make predictions about patterns in optimal allocationof time and respiratory metabolism during the dive cycle. Theresults derived from the model are (1) a diver that can varythe ratio of energy supplied anaerobically to total energy spentduring dive time is favored by natural selection, but the patternsof time allocation over the dive cycle by the diver do not differ fromthose of a diver that cannot vary the ratio. (2) Even if itis assumed that divers switch their metabolism for diving, anobvious upturn in the surface time with respect to dive timedoes not occur at the aerobic dive limit (ADL) but occurs beyondthe ADL. (3) Use of additional anaerobic metabolism can be favoredfor dives shorter than the ADL. These findings provide a usefulguide to understanding the factors that limit diving behavior.     

Purification and primary structure of ostrich pancreatic polypeptide

Pancreatic polypeptide has been isolated from ostrich pancreas by gel filtration, ion exchange chromatography and high pressure liquid chromatography. The ostrich peptide contains 36 amino acids and has an amino acid composition similar to pancreatic polypeptide of other avian species. The primary structure of ostrich pancreatic polypeptide differs from that of the chicken peptide only at residues 3 and 18 where the ostrich peptide contains an alanine and a valine residue compared to the serine and isoleucine residues found in those positions in the chicken peptide.     

Distribution and morphology of ghrelin-immunopositive cells in the cerebellum of the African ostrich

Ghrelin, the endogenous ligand for the growth hormone secretagogue receptor, has been found in the cerebellum of many vertebrates and in the gastrointestinal tract of African ostrich chicks, but little is known about its distribution in the cerebellum of the African ostrich. In the present study, the distribution and morphological characteristics of ghrelin-producing cells in the cerebellum of the African ostrich were investigated using immunohistochemistry. The results indicate that the cerebellum is divided into two sections: the outer cerebellar cortex and the inner medulla of cerebellum. The cerebellar cortex comprises a molecular layer, a Purkinje cell layer and a granular layer; ghrelin-immunopositive (ghrelin-ip) cells were localized throughout the entire cerebellum, but sparsely in the medulla. The greatest number of ghrelin-ip cells was found in the stratum granulosum, and the density decreased gradually from the molecular layer to the Purkinje cell layer in the cerebellar cortex. The ghrelin-ip cells were fusiform or irregular polygons and their cytoplasm was stained intensely. These results clearly demonstrate the presence of ghrelin-ip cells in the cerebellum of the African ostrich. It is speculated that ghrelin may have a physiological function in the cerebellum.     

Design and simulation analysis of a bionic ostrich robot

Biomechanics and Modeling in Mechanobiology - To look for the reason why the biped animal in nature can run with such high speed and to design a bionic biped prototype which can behave the high...     

Purification and characterization of the 20S proteasome from ostrich skeletal muscle

The proteasome is a high molecular weight, multisubunit and multicatalytic enzyme. Here we report the purification and characterization of ostrich skeletal muscle 20S proteasome. It was purified to homogeneity with Mr 700,000, pI 6.67 and a 'ladder' of 22.2-33.5 kDa bands on SDS-PAGE. The amino acid composition and amino-terminal sequences showed large identities to those of other species. For the three major activities, pH and temperature optima ranged between 8.0-11.0 and 40-70 degrees C, and stabilities between 5-12 and up to 40-60 degrees C. Substrate specificity and inhibitory effects were also studied. Many similarities to other sources were shown, with a few significant differences.