Duane P. Harland

Behavioural and cognitive influences of kairomones on an araneophagic jumping spider

In laboratory experiments, Portia fimbriata, an araneophagic salticid from Queensland, was influenced by olfactory and contact-chemical cues from Jacksonoides queenslandicus, an abundant salticid on which P.fimbriata preys. Four distinct effects were revealed: P.fimbriata (1) moved into and remained in the vicinity of J. queenslandicus, (2) performed undirected leaping, behaviour known to function as speculative hunting by inducing a turning response from not-yet-seen J. queenslandicus, (3) adopted a posture (retracted palps) known to be routine when stalking salticids and (4) showed enhanced attention to optical cues from J. queenslandicus. Laboratory experiments provided no statistical evidence that chemical cues from other prey species affected P.fimbriata, that J. queenslandicus was affected by chemical cues from P. fimbriata or that allopatric Portia were sensitive to chemical cues from J. queenslandicus.

Convergent evolution of eye ultrastructure and divergent evolution of vision‐mediated predatory behaviour in jumping spiders

All jumping spiders have unique, complex eyes with exceptional spatial acuity and some of the most elaborate vision‐guided predatory strategies ever documented for any animal of their size. However, it is only recently that phylogenetic techniques have been used to reconstruct the relationships and key evolutionary events within the Salticidae. Here, we used data for 35 species and six genes (4.8u2003kb) for reconstructing the phylogenetic relationships between Spartaeinae, Lyssomaninae and Salticoida. We document a remarkable case of morphological convergence of eye ultrastructure in two clades with divergent predatory behaviour. We, furthermore, find evidence for a stepwise, gradual evolution of a complex predatory strategy. Divergent predatory behaviour ranges from cursorial hunting to building prey‐catching webs and araneophagy with web invasion and aggressive mimicry. Web invasion and aggressive mimicry evolved once from an ancestral spartaeine that was already araneophagic and had no difficulty entering webs due to glue immunity. Web invasion and aggressive mimicry was lost once, in Paracyrba, which has replaced one highly specialized predation strategy with another (hunting mosquitoes). In contrast to the evolution of divergent behaviour, eyes with similarly high spatial acuity and ultrastructural design evolved convergently in the Salticoida and in Portia.

Prey classification by Portia fimbriata , a salticid spider that specializes at preying on other salticids: species that elicit cryptic stalking

Portia fimbriata from Queensland, Australia, is an araneophagic jumping spider (Salticidae) that includes in its predatory strategy a tactic (cryptic stalking) enabling it to prey effectively on common sympatric salticids from other genera. Using standardized tests in which only optical cues were available (prey enclosed in small glass vial within large cage), the reactions of P. fimbriata to 114 salticid species were investigated. Except for Myrmarachne spp. (ant mimics), all salticids tested triggered cryptic stalking by P. fimbriata. This included not only sympatric, but also allopatric, salticids. The salticid on which P. fimbriata most commonly preys in nature is Jacksonoides queenslandicus, but cryptic stalking was triggered by salticid species with considerably different appearances, including beetle mimics, species with unusual body shapes and species with a wide variety of camouflaging markings. Portia fimbriata was also tested with lycosid, clubionid, theridiid and desid spiders and with flies and ants, but none of these arthropods triggered cryptic stalking. Optical cues used by P. fimbriata for discrimination between salticid and non-salticid prey are discussed.

SPECULATIVE HUNTING BY AN ARANEOPHAGIC SALTICID SPIDER

Portia fimbriata , an araneophagic jumping spider (Salticidae), makes undirected leaps (erratic leaping with no particular target being evident) in the presence of chemical cues from Jacksonoides queenslandicus , another salticid and a common prey of P.fimbriata . Whether undirected leaping by P.fimbriata functions as hunting by speculation is investigated experimentally. Our first hypothesis, that undirected leaps provoke movement by J. queenslandicus , was investigated using living P.fimbriata and three types of lures made from dead, dry arthropods ( P.fimbriata , J. queenslandicus and Musca domestica ). When a living P.fimbriata made undirected leaps or a spring-driven device made the lures suddenly move up and down, simulating undirected leaping, J. queenslandicus responded by waving its palps and starting to walk. There was no statistical evidence that the species from which the lure was made influenced J. queenslandicus response in these tests. Our second hypothesis, that J. queenslandicus reaction to J. queenslandicus when J. queenslandicus reacted to lures simulating undirected leaping. In these tests, P.fimbriata responded by turning toward J. queenslandicus and waving its palps.

Weak and strong priming cues in bumblebee contextual learning

SUMMARY Bees have the flexibility to modulate their response to a visual stimulus according to the context in which the visual stimulus is seen. They readily learn that in one context a yellow target, but not a blue one, should be approached to reach sucrose and that in another context blue, but not yellow, leads to sucrose. Here we contrast the bumblebees ability to use two types of contextual or priming cue in deciding which of two coloured targets to approach. Bumblebees could perform this task well when the pairs of colours to be discriminated were in two different places, so that the cues associated with each place indicated whether the bees should select a blue or a yellow target. In this case the priming cues were presented concurrently with the rewarded stimuli. Priming cues, which occur a little earlier than a rewarded stimulus, seem less powerful in their ability to bias a bees choice of rewarded stimulus. We tried with a variety of methods to train bees to use a priming colour to indicate which of two colours should be approached a few seconds later. Our only success with such sequential priming cues was when each pair of rewarded and unrewarded colours could be distinguished by additional spatial cues. Bees were trained to choose a blue-black checkerboard over a yellow-black checkerboard, after viewing a yellow priming cue, and to choose a uniform yellow target over a uniform blue one, after viewing a blue priming cue. They performed this task almost without error. To see whether bees had associated each rewarded stimulus with the relevant sequential priming cue, bees were tested with a choice between the two rewarded stimuli (the yellow target and the blue-black checkerboard). The bees choice was biased towards the blue-black checkerboard, when the preceding priming cue was yellow, and towards the yellow target, when the priming cue was blue. We suppose that the experiment works because the presence or absence of the checkerboard provides an additional distinguishing spatial cue that can be linked to and reinforce the sequential one. Under natural conditions, as when bees follow routes, there will normally be such a synergy between spatial and sequential cues.

PREY-CAPTURE TECHNIQUES AND PREY PREFERENCES OF AELURILLUS AERUGINOSUS, A. COGNATUS, AND A. KOCHI, ANT-EATING JUMPING SPIDERS (ARANEAE: SALTICIDAE) FROM ISRAEL

ABSTRACT Aelurillus aeruginosus, A. cognatus, and A. kochi feed on ants in nature. Prey-capture techniques and prey preferences of each of these three species from Israel were studied in the laboratory using a wide range of ants and other insects. Each usually attacked ants head on, but there was no regular orientation of attacks on other insects. When attacking ants, but not other prey, each species tended to stab several times before holding on. In three different types of tests for prey preference, “well-fed” (fed 5 days prior to testing) and “starved” (fed 15 days prior to testing) individuals of each species took dolichoderine, formicine, and myrmicine ants in preference to a variety of other insects (Diptera, Hemiptera, Isoptera, and Pscoptera). When extra-starved (21-day fast), however, each species took ants and other insects indiscriminately. Testing with laboratory-reared salticids showed that preference and prey-capture behavior did not depend on prior experience with ants. When tested with dea...

One small leap for the jumping spider but a giant step for vision science.

![Figure][1] nnWeasels may be cunning, we might admire the intelligence of dogs and cats, but we can be forgiven for expecting the jumping spider, a diminutive predator with a brain not much bigger than a poppy seed, to be one of Descartes automatons. Yet, jumping spiders, also known as

Lateral eyes direct principal eyes as jumping spiders track objects

One way of circumventing the functional tradeoffs on eye design [1,2] is to have different eyes for different tasks. For example, jumping spiders (Salticidae), known for elaborate, visually guided courtship and predatory behavior [3], view the same object simultaneously with two of their four pairs of eyes: the antero-lateral eyes (ALEs) and the principal eyes (reviewed in [2]; Figure 1A). The ALEs, with immobile lenses and retinas, wide fields of view, and hyperacute sensitivity to moving stimuli [4], are structurally distinct from the principal eyes, which have the best spatial acuity known for terrestrial invertebrates and can discern fine details of stationary objects [5]. Behind the immobile corneal lenses of the principal eyes are miniature, boomerang-shaped retinas with correspondingly small fields of view (Figure 1B). The principal-eye visual fields are greatly expanded and overlap because of eye movements: these retinas are at the proximal ends of long, moveable tubes within the spiders cephalothorax [6]. By designing and using a specialized eyetracker, we tested whether principal-eye gaze direction is influenced by what the ALEs see. The principal eyes scanned stationary objects regardless of whether the ALEs were masked, but only when the ALEs were unmasked did the principal eyes smoothly track moving disks. The principal eyes, with high acuity but a narrow field of view, can thus precisely target moving stimuli, but only with the guidance of the secondary eyes.