Prey catching in archer fish: the role of posture and morphology in aiming behavior.

Archer fishes (Toxotidae) bring down aerial prey with a squirt of water from their mouth. How they aim, however, is not clear. Measurements of the angle between the squirt and the fish's body axis (the mouth angle) already yielded agreement that pointing the body plays a part in aiming, and it has been suggested that more accurate aiming would occur by means of lips and tongue. In a previous study, however, we found that the mouth angle is an individual property, with a much smaller range than reported by others. Moreover, we found that archer fishes do not possess movable lips, and that their tongue seems too short to direct the squirt. Presently, we found that the tongue cannot even reach the rostral part of the mouth cavity, that affects the squirt's direction, and that the mouth angle is an individual property remaining constant, even across a wide range of target distances. These findings suggest that aiming the body is the only way of aiming the squirt. We also found that during aiming, the body rotates around the eyeballs which remain fixed in space. The position of the eyeballs in the head (eye angle) at the moment of squirting was also found to be an individual property. However, the eye angle is less constant than the mouth angle. The systematic variance of the eye angle probably is related to the refraction effect.

Housing and care of monkeys and apes in laboratories: adaptations allowing essential species-specific behaviour.

During the last two decades an increasing amount of attention has been paid to the housing and care of monkeys and apes in laboratories, as has been done with the housing and care of other categories of captive animals. The purpose of this review is to develop recommendations for adaptations of housing and care from our knowledge of the daily behavioural activity of monkeys and apes in natural conditions and in enriched laboratory conditions. This review deals mainly with adaptations of daily housing and care with respect to behaviour, and it is restricted to commonly-used species: Callitrichidae (Callitrix jacchus, Saguinus oedipus); Cebidae (Aotus trivirgatus, Saimiri sciureus, Cebus apella); Cercopithecidae (Macaca fascicularis, M. mulatta, M. nemestrina, M. arctoides, Chlorocebus aethiops, Papio hamadryas, P. cynocephalus); Pongidae (Pan troglodytes).

Prey catching in the archer fish: angles and probability of hitting an aerial target.

When trying to squirt down aerial arthropods, archer fishes (Toxotidae) have to cope with the displacement of the image of the target by refraction of light at the water surface. It has been suggested, and accepted, that Toxotes jaculatrix would avoid the effect of refraction by squirting vertically. In our previous study, however, Toxotes chatareus was observed to squirt under a wide range of angles, including angles much smaller than 90 degrees. The aim of the present study was to asses in T. chatareus (N=15), the frequency distribution of angles used, the relation between angle and probability to hit, the relation between target height and angle, and the smallest angles the fishes can use. The outcome was a distribution with a range of 102-58 degrees and a median of 74 degrees, no relation between angle and probability to hit, no relation between target height and angle and a smallest angle of 45 degrees. The results clearly indicate that T. chatareus does not evade the refraction effect by squirting only vertically (90 degrees ), but masters a considerable refraction effect thanks to a mechanism that is not investigated here. The capacity to hit prey under a wide range of angles is seen as an important adaptation to the natural habitat where the visibility of prey is restricted by vegetation. The constraints of the range of angles are discussed.

Do young guinea pigs (Cavia porcellus) develop an attachment to inanimate objects?

Filial imprinting has been studied extensively in precocial birds. In these studies, inanimate objects were used as imprinting objects. Although attachment to the parents is common in mammals, experiments with inanimate objects are rare and mostly restricted to guinea pigs (Cavia porcellus). The results of these studies are inconclusive. The aim of the present experiment was to assess whether guinea pigs can develop an attachment to inanimate objects. For this purpose, 11 young guinea pig pups were taken from their mothers within 16 h after birth, and subsequently reared individually in the presence of an inanimate object. Between 2 and 35 days of age, the pups were submitted to preference tests as well as separation tests. Neither test provided evidence of attachment: during separation, the pups did not increase their distress calling; moreover, pups preferred a novel object to their rearing object in the preference tests.

Persistent neophobic behaviour in monkeys: A habit or a trait?

Studies on the effects of rearing conditions on behavioural development showed that most monkeys reared with surrogate mothers persistently avoided a big novel object (paper bag) whereas most monkeys reared by natural mothers would approach it. Conditioned fear and conditioned avoidance, observational learning, and lack of support by the mothers' presence could be excluded as possible causes; we established that the high incidence of phobic behaviour in surrogate-reared groups was caused by deprivation of maternal care. Results of further studies showed that the avoidance was not restricted to the object the Ss had been exposed to in infancy; monkeys still avoiding the bag at 2 years also avoided other big novel objects. Some researchers have found differences in the neurobiological status between surrogate-reared monkeys and mother-reared monkeys. However, the results of our experiments showed that both types of rearing condition produced avoiders as well as non-avoiders. The question under discussion here is whether avoidance of novelty is a habit or a trait. The relative importance of features of surrogates versus real mothers, characteristics of infants and differences in mothering style is discussed.

Mobile surrogate mothers and the development of exploratory behavior and radius of action in infant long-tailed macaques (Macaca fascicularis).

One of the effects of rearing young monkeys on surrogate mothers is a delay in the development of exploratory behavior. An important question is which difference between mother and surrogate mother caused this delay. We hypothesized that the mothers' carrying the infant through the environment promotes the development of exploratory behavior and the radius of action of infant macques. Using surrogate mothers, we reared 9 infants in a peer group with immobile surrogates and 10 infants in another peer group with mobile surrogates. During the 3rd to the 6th month, we observed each infant for 30 min weekly, collecting observational data on several behavioral parameters and on time spent in several areas in the cage. Results showed that exploratory behavior and an increase in radius of action developed more rapidly in the mobile-reared infants.

Responses to novelty in phobic and non-phobic cynomolgus monkeys: the role of subject characteristics and object features.

In two previous studies it has been shown that most surrogate-reared cynomolgus monkeys became phobic of a harmless object (a big paper bag) while most mother-reared monkeys approached that object. Results of the first study seemed to indicate that the phobic reaction was restricted to the bag. Barnett and Cowan (Interdisciplinary Science Review, 1, 43-62, 1976) and Suomi (Anxiety disorder in childhood, pp. 1-23, 1986), however, reported that subjects (respectively rats and monkeys) that avoided a first novel object also avoided subsequent novel objects. In the present study we exposed phobic (bag-avoiding) and non-phobic (bag-approaching) monkeys from the study by Röder, Timmermans and Vossen (Behaviour Research and Therapy, 27, 221-231, 1989) to several big and small novel objects. Our results show that, irrespective of their rearing conditions, subjects that were phobic also avoided big novel objects while subjects that were non-phobic approached big novel objects. The reaction to small novel objects was independent of the previous reaction to the bag.

The role of modeling in prevention and extinction of phobic behaviour in cynomolgus monkeys (Macaca fascicularis).

In previous studies surrogate reared cynomolgus monkeys have been shown to become phobic of an unprepared harmless object. In the present study an attempt was made to prevent the development of phobic behaviour in young monkeys and to extinguish avoidance behaviour in phobic monkeys. In the first experiment subjects were exposed to the object in company of their (surrogate) mothers which approached the object. In the second experiment phobic subjects were exposed to the object in company of non-phobic conspecifics which approached the object. The results of the first experiment show that modeling was unsuccessful in preventing the acquisition of phobia in the surrogate-reared monkeys but seemed successful in accelerating approach in the mother-reared subjects. The results of the second experiment show that during the modeling treatment the phobic subjects followed the model and approached the object. However, in post treatment tests all subjects but one relapsed into avoidance. The effect of modeling during treatment is interpreted in terms of coactive facilitation.

Effects of rearing and exposure condition upon the acquisition of phobic behaviour in cynomolgus monkeys.

Young monkeys were confronted with a harmless novel object in their familiar home-cage environment. The effects of two rearing conditions (mother and surrogate mother) and two confrontation conditions [presence and absence of the (surrogate) mother] upon the acquisition of phobic behaviour were studied. Most surrogate-reared monkeys showed persistent maladaptive avoidance behaviour with respect to the object during tests, from 7 months of age onwards. Most mother-reared monkeys approached the object during tests taking food near it, from 7 months onwards. The confrontation condition had no effect upon behaviour with respect to the object. As no aversive conditioning procedures have been applied, merely presenting a harmless object appears to be enough to set off persistent avoidance in surrogate-reared monkeys. Further investigation of the origin of the phobic behaviour is interesting in view of developing animal models of human phobias of which no conditioning history is known.

Rearing cynomolgus monkeys (Macaca fascicularis) on surrogate mothers with bottle feeding.

Fifty-two cynomolgus monkeys were reared in peer groups on surrogate mothers and fed by bottle during the first months of life. A description of the technique of bottle feeding and the structure of surrogate mothers is presented. Results are shown in a growth curve. Inter-individual differences in body weight were very large. The mean weight was higher in males than in females, but no significant sex differences in growth occurred. The weight of mother-reared infants stayed within the standard deviation of the mean weight of the artificially-reared subjects.

Role of dam and pups in the absence of nursing in CPB-B rats (rattus norvegicus).

In rats of the CPB-B strain, the female shows normal parturition behaviour and normal capacity of milk secretion, but the young - all born alive - die within few days of birth. Here, we report that this postnatal mortality is eliminated when CPB-B neonates are crossfostered to mothers of the Wu:Cpb strain; conversely, Wu:Cpb neonates (which are successfully reared by dams of their own strain) die within few days of birth when crossfostered to newly parturient CPB-B rats. It is suggested that pup mortality in CPB-B rats is due to inadequate maternal care resulting, supposedly, from susceptibility of the mother to disturbing environmental stimuli.

Strain differences in parturition behavior and survival probability in rats (Rattus Norvegicus).

Three strains of laboratory rats (Wu:Cpb, CPB-B and WKY/Cpb) differing widely in reproductive success were compared concerning the role played by maternal behavior in the survival probability of pups. Parturition behavior of the dams was selected for study as pups are most dependent on the mother's behavior at, and immediately after birth. Great strain differences in survival rate of life born pups were found. However, differences between strains in parturition behavior were found to be restricted to only one pup oriented behavior and some non social behaviors. Besides no pups died at the day of birth nor did it seem probable that the strain differences we found in parturition behavior can be held responsible for the eventual death of pups during parturition. The suggestion is presented that strain differences in maternal behavior which affect survival chances of pups are to be looked for in the lactation period.

Determination of plasma concentrations of underivatized cyclophosphamide by capillary gas chromatography.

A sensitive method for the clinical determination of cyclophosphamide in 0.2 ml plasma by capillary gas chromatography with nitrogen-phosphorus detection is described. A detection limit of 50 nl/ml is readily obtainable, which is sufficiently low to measure the cyclophosphamide concentrations occurring in clinical practice. The selection of internal standards and the use of the nitrogen-phosphorus detection system is discussed, as well as eventualities for determination of cyclophosphamide metabolites.

Reproduction of cynomolgus monkeys (Macaca fascicularis) in harems.

Adult monkeys caught in the wild were housed in 2 harems and used for breeding during 7 successive years. Monkeys born in captivity and reared in the parental groups or in peer groups were also used for breeding. The live birth production rate amounted to 80% and reproduction was stable over the 7 year period. All but one of the females born in captivity showed normal maternal behaviour towards their firstborn infants. Aggression between females, breech deliveries, infanticide and reluctance of the male to copulate with females which grew up in his harem, were significant factors that reduced productivity.