摘要:

Littorina irroratadisplaced from their natural location amid plant stems in the upper inter‐tidal zone to areas of intertidal zone devoid of vegetation, oriented onshore under all sky and light conditions tested. The responses of snails tested in experimental arenas in the upper intertidal zone indicated that the natural substrate slope of 3 degrees was ignored in favor of movement toward a black paper rectangle. Subsequent releases on natural substrate supported the conclusion that the onshore‐oriented response resulted from visual perception of a dark area (bushes and trees near the high tide line). Where vegetation was equally tall in all directions, snails oriented toward the closest vegetation regardless of the actual onshore direction.

ISSN:0091-181X    

DOI:10.1080/10236247809378542

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The behaviour of ragworms,Nereis diversicolor,kept under constant conditions is organized in irregular bouts of activity and rest. Worms usually perform a number of different acts during bouts of activity but the sequences in which they occur are highly flexible. It is suggested that acts, or perhaps groups of them forming motivational systems, “compete”; with one another for ongoing priority. Fluctuations in the levels of causal factors associated with the performance of different acts are probably important in allowing them to replace one another as the ongoing behaviour. Sudden tactile stimulation presented during the performance of an act leads to its interruption; it can do so either temporarily, as when it occurs during irrigation (worms return to this act after the interruption) or permanently, as when it occurs during searching.

ISSN:0091-181X    

DOI:10.1080/10236247809378543

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

In common with a number of other echinoderm collagenous structures, the intervertebral ligament ofOphicomina nigrabehaves like a viscous fluid when stressed by a constant load. Behaviour under constant load is affected by potassium ions which increase the rate of extension and cause rupture. Since this response is specific to potassium and is blocked by anaesthetics, it is concluded that it occurs by nervous mediation. This supports the view that brittlestar arm autotomy involves a nervously mediated change in the mechanical properties of the intersegmental connective tissues. The mechanical behaviour of the ligament is sensitive to ambient pH and divalent cations. It is suggested that changes in mechanical properties may be produced by the availability of calcium ions within the interfibrillar matrix of the connective tissue. The ophiuroid intervertebral ligament is another example of an echinoderm collagenous structure whose mechanical propertiesare subject to nervous control, a phenomenon which on present knowledge is unique to the Echinodermata.

ISSN:0091-181X    

DOI:10.1080/10236247809378544

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Recent neurobiological studies on molluscs have concentrated on the analysis of relatively complex behaviour, whereas many localized reflex movements of the body do not form part of centrally determined neural programmes. The central ganglia, nerve trunks and neuron somata ofArmina californicahave been described with special reference to some of the smaller neurons in the pedal ganglia which are shown to control reproducible movements of the mantle, foot and oral veil. Similar movements are observed as part of normal behavioural responses.

ISSN:0091-181X    

DOI:10.1080/10236247809378545

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Intracellular and extracellular recordings from the stem, gastrozooids, palpons, tentacles and nectophores of physonectid siphonophores are presented. The stem organization previously described forNanomiaapplies with only minor differences toForskaliaandAgalma.The endodermal epithelium of the stem is shown to be the pathway for slow potentials.

ISSN:0091-181X    

DOI:10.1080/10236247809378546

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0091-181X    

DOI:10.1080/10236247809378541

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor