摘要:

Euphausiid shrimps bear light organs, two pairs in the thorax, and four similar single organs in the abdomen: A pair on the eyestalks differ in structure from these others, and are not considered further by us. In most species the size of the organs is related to that of the animal, but they are relatively smaller in deeper living species. In some species certain light organs are larger in males. The flashes of light emitted begin abruptly, remain steady for several seconds and die away slowly. Euphausiids flash in response to light, including that of another euphausiid, and to certain drugs, notably 5 hydroxytryptamine and certain analogues.The photophores contain a lantern where the light is generated, and three separate optical components which reflect and refract the light out of one pole of the organ. Our interpretation of the structures suggests that light generation is probably controlled by alteration of the blood flow through the lantern, and that this in turn is under nervous control.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1978.tb03932.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

This paper describes the structure of the otter anal scent sacs. The deposited secretion contains apocrine gland protein and polymucosaccharide and sebaceous gland lipid. Chemical analyses by gas‐liquid chromatography and acrylamide gel electrophoresis revealed individual differences in the composition of secretion. The individual differences in protein bands as revealed by electrophoresis were stable with time and may be useful in following the movements of wild otters in the field.A captive pair of otters produced deposits of secretion with a periodicity similar to that of the female oestrous cycle, with both sexes producing deposits around oestru

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1978.tb03933.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

A new measure of sexual dimorphism in tooth size (Relative Male Tooth Size) is estimated for a sample of 39 primate species and is used to test predictions concerning the adaptive significance of sexual dimorphism in primate tooth size. It is concluded that both sexual selection and predator defence are important selective forces producing marked sexual dimorphism in the teeth used for fighting.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1978.tb03934.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Calls were recorded from eggs, chicks and juveniles of the Aldabra White‐throated railDryolimnas cuvieri aldabranus.A sonagraphic analysis was made of these calls, their behavioural contexts described and probable functions suggested. Three calls, the twitter, tiuu and contented peep were produced by chicks in the egg. All three calls may be derived from the basic peep first recorded some 36 hours before hatching. Shortly after hatching two more calls, the distress call and the alarm call, can be elicited from the rail chicks. Contented peeps and twitters are restricted to the repertoire of young rails. Song was first heard from wild rail chicks at the age of ten days and may develop from the contented peep. Three adult calls, the 'mp yeah, 'mptiuu and 'mpclick appear at the age of three months and six months later the adult vocal repertoire is completed by the appearance of 'mps, toks, purrs and nest‐defence squeals. With the exception of the 'mp, all adult calls can be derived from the vocalizations of chicks and juveni

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1978.tb03935.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The ecology of two commercially important catfish species,Clarias gariepinusand C.ngamensis, was examined in the Elephant Marsh, southern Malawi. Abundance, distribution, and movements within the marsh system were studied. Growth rates were determined from rings on the vertebrae, with corroborative evidence from length frequency analyses and tagging studies. Breeding seasons, length and age at maturity, and fecundity were determined for both species. Stomach contents were examined and the food preferences of the two species were compared.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1978.tb03936.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1978.tb03937.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY