Demorest Davenport

Simulation of simple models of animal behavior with a digital computer

Abstract The effects of kinetic, klinokinetic, orthokinetic and tropotaxix behavior were simulated on a digital computer in order to study the interactions between these simple behaviors and the effect of sensory adaptation under completely controlled experimental conditions. The conclusions of Ulyott that klinokinetic behavior in the presence of sensory adaptation can cause a directional displacement of an organism along a gradient of stimulus intensity were confirmed. In addition it was found that inverse klinokinetic and direct orthokinetic behavior (with sensory adaptation) result in a marked directional displacement up a gradient. However, direct klinokinetic behavior cancels out the effect of direct orthokinetic behavior.

THE EFFECTS OF TEMPERATURE AND SALINITY CHANGE ON SWIMMING RATE IN THE DINOFLAGELLATES, GONYAULAX AND GYRODINIUM

1. Apparatus is described with which it is possible to make rapid measurements of linear velocity and rate of change of direction in the motile microorganism.2. Observations on the relation between linear velocity and salinity have been made in the dinoflagellates, Gonyaulax and Gyrodinium.3. Data are also presented on the relation of linear velocity to temperature in the two forms.4. Results are discussed in relation to the ecology of the organisms.

The Chumash and the swordfish

Linguistic, ethnographic, archaeological and technical evidence demonstrates the mythological and ceremonial importance of the swordfish in Chumash culture. From at least the 1st century AD, there existed among the Chumash of the Santa Barbara region, California, a productive fishery for swordfish (Xiphias gladius) by harpoon. The probability is that a shamanistic cult was intended to bring this great ‘master of the sea’ within reach of fishermen and to persuade it occasionally to drive whales ashore, making their meat available. Evidence from a number of world-wide sources shows that this Chumash belief was, indeed, founded in fact.

BEHAVIORAL SPECIFICITY AND THE INDUCTION OF HOST RECOGNITION IN A SYMBIOTIC POLYCHETE

1. Several populations of the symbiotic polychaete Arctonoe pulchra were examined with regard to the ability of these worms to detect chemical signals emanating from their hosts. Four of the five experimental populations exhibited chemotactic responses which can be interpreted as host recognition.2. The host recognition responses were for the most part very specific in that worms consistently chose their original host when presented effluents from a variety of organisms in a Y-maze choice apparatus.3. The specificity of these chemotactic responses could be affected by the previous experience of individual worms. That is, worms could be conditioned to respond to an organism which previously was unattractive to them.4. The mechanisms involved in effecting this modification of behavior are not clear. However, the results of this study indicate a heretofore unknown behavioral capability among these polychaetes.

THE SENSORY BASIS OF HOST RECOGNITION BY SYMBIOTIC SHRIMPS, GENUS BETAEUS

1. The sensory basis of host-oriented locomotion in the caridean Betaeus macginitieae contrasts with that of the congeneric B. harfordi. Both of these shrimps can locate their respective host organisms utilizing chemical stimuli of host origin. Only B. macginitieae demonstrates the ability to utilize visual stimuli for this same purpose.2. By using information contained in multiple stimulus modalities, B. macginitieae is able to maintain a more restricted host association than its congener.3. Visual recognition of its urchin host by B. macginitieae does not involve any parameter of the total visual pattern of the urchin that uniquely characterizes the urchin species, but appears to be a generalized response to larger, dark forms of undefined peripheral outline.4. Positive rheotaxis in the presence of appropriate non-directional chemical stimuli is suggested as the mechanism by which B. harfordi effects chemically-mediated host location.

AGRAULIS AND PASSIFLORA I. CONTROL OF SPECIFICITY

1. Prior to an investigation of the sensory modalities and behavior involved in host-plant selection by Agraulis vanillae incarnata (Riley), experiments were conducted to evaluate the relative influence of larval feeding behavior, adult ovipositional behavior, and host-specific butterfly mortality in determining the infestation of various species of host-plant in the genus Passiflora.2. The larvae demonstrated induced feeding preferences for some, but not all, species of Passiflora upon which they had previously been raised.3. The adult females exhibited definite, fixed ovipositional preferences among six species of Passiflora available in Santa Barbara County. These preferences were not affected by either larval diet or induced feeding preference.4. The food plant suitability of the six local species of Passiflora varied considerably as indicated by several aspects of Agraulis growth, development, and reproduction. With a few notable exceptions this food plant suitability broadly correlated with the adul...

Analyses of the behaviour of commensals in host-factor. 1. A hesioned polychaete and a pinnotherid crab

Abstract 1. 1. A new apparatus is described for the investigation of the responses of aquatic animals to chemical agents. 2. 2. With the apparatus it has been demonstrated in exploratory tests that in the facultative commensal polychaete Podarke pugettensis a positive chemotropotaxis is probably the most important behavioural mechanism involved in “host-finding.” “Direct” orthokinetic and klino-kinetic responses may aid the animal. 3. 3. Detailed experiments with the obligate commensal pinnotherid crab Pinnixa chaetopterana indicate that this crab shows a strong “direct” klinokinesis in host-factor. Under the conditions of our experiments, chemotropotactic responses can be discerned in steep gradients. Rheotactic responses are not present. 4. 4. The response specificity of this crab has been investigated. Evidence is presented that the host-factor concerned is a protein.

STUDIES IN THE PHYSIOLOGY OF COMMENSALISM. 2. THE POLYNOID GENERA ARCTONOE AND HALOSYDNA

1. Water from an aquarium from which a host Evasterias troschelii has been removed 24 hours before no longer possesses an attraction for commensal Arctonoe fragilis. Similar results were obtained five hours after removal.2. Water from an aquarium from which a host Evasterias has been removed with difficulty, so that tube feet were torn from it, has no attraction for commensals almost immediately after removal of the host. Such water appears to repel them.3. Water from an aquarium from which a host Evasterias has been removed with comparative ease (involving less disturbance to the starfish) retains its attraction for commensals immediately after removal, but shortly thereafter the attraction appears to weaken.4. If a host Evasterias is suspended in a test aquarium in a dialyzing bag for two hours, at the end of this time not enough attractant has passed through to attract commensals.5. Experiments to determine whether attractant will diffuse through a dialyzing bag in effective concentrations overnight ma...

Red and Far-Red Light Effects on a Short-Term Behavioral Response of a Dimoflagellate

Cessation of movement (stop response) is used as a criterion for light reception by the dinoflagellate Gyrodinium dorsum Kofoid. Brief irradiation (2 seconds at 470 nanometers) elicits a stop response in cells any time during the 6-minute interval after removal from growth lights. This stop response is inactivated by exposure for 4 minutes to 470-nanometer light prior to stimulation. Red light (620 nanometers) reactivates this stop response, and far-red light (700 nanometers) reverses this reactivation. This red-far-red photo reversibility is taken as evidence for phytochrome involvement.

THE LUMINESCENCE OF THE MILLIPEDE, LUMINODESMUS SEQUOIAE

1. The luminescence of Luminodesmus is continuous, but fluctuates by 20 to 40 per cent or more. The mechanism by which light emission is controlled is not known. No evidence was found for the suggestion that the light is bacterial in origin.2. The luminescence is green with a maximum emission at 495 mµ and is optimal at a temperature of 31.5° C. Light emission is greatest in pure oxygen and extinguished in pure nitrogen. An oxygen concentration of 6.5% decreased the intensity from that in air by about one half.3. Luminescence in water extracts of dried acetone powders has been demonstrated.4. We have not been able to restore luminescence to dark extracts either by the classical luciferin-luciferase technique or by adding a variety of biochemical intermediates. We have found that if adenosine triphosphate is added to extracts while they are luminescing an increase in light intensity occurs.