The induction of metamorphosis of marine invertebrate larvae: stimulus and response

1983 ◽  
Vol 61 (8) ◽  
pp. 1701-1719 ◽  
Author(s):  
Robert D. Burke

The induction of metamorphosis by environmentally derived cues is reviewed in barnacles, molluscs, hydroids, echinoids, and ascidians in the context of the neurological and behavioral model of stimulus and response. The model proposes that cues associated with preferred juvenile or adult habitats are the stimuli. Stimuli are received by receptors that communicate with the effectors of metamorphosis, larval and adult tissues. The response is a combination of morphogenetic, histolytic, and histogenic processes. Receptors in all five taxa are assumed to be superficial sensory receptors, though there is no direct evidence for their involvement in the perception of cues. Although the induction of metamorphosis by environmental cues in all five taxa fits well within a stimulus–response model, there is currently only circumstantial evidence for neural or endocrine control of metamorphosis.

The functional properties of marine invertebrate larvae represent the sum of the physiological activities of the individual, the interdependence among cells making up the whole, and the correct positioning of cells within the larval body. This chapter examines physiological aspects of nutrient acquisition, digestion, assimilation, and distribution within invertebrate larvae from an organismic and comparative perspective. Growth and development of larvae obviously require the acquisition of “food.” Yet the mechanisms where particulate or dissolved organic materials are converted into biomass and promote development of larvae differ and are variably known among groups. Differences in the physiology of the digestive system (secreted enzymes, gut transit time, and assimilation) within and among feeding larvae suggest the possibility of an underappreciated plasticity of digestive physiology. How the ingestion of seawater by and the existence of a circulatory system within larvae contribute to larval growth and development represent important topics for future research.


2016 ◽  
Vol 8 (4) ◽  
pp. 87 ◽  
Author(s):  
Nagasimha Balakrishna Kanagal

<p>The stimulus response model of consumer behaviour is useful to understand the buying behaviour of individual consumers in the context of individuals buying consumer products. An extended stimulus-response model of behavioural processes in consumer decision making is proposed that serves to integrate the influences and interlinkages of buyer psychology, various buyer characteristics, and the impact of the buyer decision process on consumer decision making. The model proposes that the behavioural process of consumer decision making be as a result of the interaction of three aspects of individual buyer behaviour: communication sensitivity; enculturated individuality; and rational / economic decision making. The paper addresses the flip side of the consumer decision making process in terms of the five stages of decision making from need recognition to post-purchase satisfaction. An aggregate level framework of behavioural process in consumer decision making has been provided, that could lead to a richer analysis of micro level factors and relationships influencing consumer decision behaviour.</p>


2008 ◽  
Vol 214 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Jonathan D. Allen

Author(s):  
Juergen Perl

In particular in technical contexts, information systems and analysing techniques help a lot for gathering data and making information available. Regarding dynamic behavioral systems like athletes or teams in sports, however, the situation is difficult: data from training and competition do not give much information about current and future performance without an appropriate model of interaction and adaptation. Physiologic adaptation is one major aspect of targetoriented behavior, in physical training as well as in mental learning. In a simplified way it can be described by a stimulus- response-model, where external stimuli change situation or status of an organism and so cause activities in order to adapt. This aspect can appear in quite different dimensions like individual biochemical adaptation that needs only milliseconds up to selection of the fittest of a species, which can last millions of years. Well-known examples can be taken from learning processes or other mental work as well as from sport and exercising. Most of those examples are characterized by a phenomenon that we call antagonism: The input stimulus causes two contradicting responses, which control each other and – by balancing out – finally enable to reach a given target. For example, the move of a limb is controlled by antagonistic groups of muscles, and the result of a game is controlled by the efforts of competing teams. In order to understand and eventually improve such adaptation, models are necessary that make the processes transparent and help for simulating dynamics like for example, the increase of heart rate as an reaction of speeding up in jogging. With such models it becomes possible not only to analyze past processes but also to predict and schedule indented future ones. In the Background section, main aspects of modeling antagonistic adaptation systems are briefly discussed, which is followed by a more detailed description of the developed PerPot-model and a number of examples of application in the Main Focus section.


The Condor ◽  
2000 ◽  
Vol 102 (1) ◽  
pp. 35-51 ◽  
Author(s):  
Jerry D. Jacobs ◽  
John C. Wingfield

Abstract Most organisms live in seasonal environments that fluctuate on a predictable schedule and sometimes unpredictably. Individuals must, therefore, adjust so as to maximize their survival and reproductive success over a wide range of environmental conditions. In birds, as in other vertebrates, endocrine secretions regulate morphological, physiological, and behavioral changes in anticipation of future events. The individual thus prepares for predictable fluctuations in its environment by changing life-cycle stages. We have applied finite-state machine theory to define and compare different life-history cycles. The ability of birds to respond to predictable and unpredictable regimes of environmental variation may be constrained by the adaptability of their endocrine control systems. We have applied several theoretical approaches to natural history data of birds to compare the complexity of life cycles, the degree of plasticity of timing of stages within the cycle, and to determine whether endocrine control mechanisms influence the way birds respond to their environments. The interactions of environmental cues on the timing of life-history stages are not uniform in all populations. Taking the reproductive life-history stage as an example, arctic birds that have short breeding seasons in severe environments appear to use one reliable environmental cue to time reproduction and they ignore other factors. Birds having longer breeding seasons exhibit greater plasticity of onset and termination and appear to integrate several environmental cues. Theoretical approaches may allow us to predict how individuals respond to their environment at the proximate level and, conversely, predict how constraints imposed by endocrine control systems may limit the complexity of life cycles.


Author(s):  
P. J. Hayward ◽  
Paul H. Harvey

The spatial settlement of marine invertebrate larvae is not a random process. The distribution of the adults of a particular species is influenced by the behavioural responses of the animal to a range of environmental stimuli which, in the case of many sessile invertebrates, result in the display of clear substrate selection. The role of habitat selection in determining the distribution of aquatic invertebrates has been the subject of a review by Meadows & Campbell (1972). The selection of algal substrata by the larvae of various intertidal species of Bryozoa has been demonstrated by Ryland (1959); among these, the ctenostomatous bryozoans Alcyonidium hirsutum and A. polyoum were shown to exhibit a strong preference for fronds of the alga Fucus serratus, an experi-mental result which accorded well with the distribution of the two species on the shore (Ryland, 1962).


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