Visual antipredator effects of web flexing in an orb web spider, with special reference to web decorations.

Some visual antipredator strategies involve the rapid movement of highly contrasting body patterns to frighten or confuse the predator. Bright body colouration, however, can also be detected by potential predators and used as a cue. Among spiders, Argiope spp.

Physiological properties of the visual system in the Green Weaver ant, Oecophylla smaragdina.

The Green Weaver ants, Oecophylla smaragdina are iconic animals known for their extreme cooperative behaviour where they bridge gaps by linking to each other to build living chains. They are visually oriented animals, build chains towards closer targets, use celestial compass cues for navigation and are visual predators. Here, we describe their visual sensory capacity.

Visual signals in the wing display of a tephritid fly deter jumping spider attacks.

Visual animal communication, whether to the same or to other species, is largely conducted through dynamic and colourful signals. For a signal to be effective, the signaller must capture and retain the attention of the receiver. Signal efficacy is also dependent on the sensory limitations of the receiver.

Fast acrobatic maneuvers enable arboreal spiders to hunt dangerous prey.

Spiders, the most specious taxon of predators, have evolved an astounding range of predatory strategies, including group hunting, specialized silk traps, pheromone-loaded bolas, and aggressive mimicry. Spiders that hunt prey defended with behavioral, mechanical, or chemical means are under additional selection pressure to avoid injury and death. Ants are considered dangerous because they can harm or kill their predators, but some groups of spiders, such as the Theridiidae, have a very high diversification of ant-hunting species and strategies [J.

AnimalTraits - a curated animal trait database for body mass, metabolic rate and brain size.

Trait databases have become important resources for large-scale comparative studies in ecology and evolution. Here we introduce the AnimalTraits database, a curated database of body mass, metabolic rate and brain size, in standardised units, for terrestrial animals. The database has broad taxonomic breadth, including tetrapods, arthropods, molluscs and annelids from almost 2000 species and 1000 genera.

Nocturnal ants have faster temporal resolution at low light levels but lower adaptability compared to diurnal relatives.

Nocturnal insects likely have evolved distinct physiological adaptations to enhance sensitivity for tasks, such as catching moving prey, where the signal-noise ratio of visual information is typically low. Using electroretinogram recordings, we measured the impulse response and the flicker fusion frequency (FFF) in six congeneric species of ants with different diurnal rhythms. The FFF, which measures the ability of an eye to respond to a flickering light, is significantly lower in nocturnal ants (∼125 Hz) compared to diurnal ants (∼189 Hz).

Anesthesia disrupts distance, but not direction, of path integration memory.

Solitary foraging insects, such as ants, maintain an estimate of the direction and distance to their starting location as they move away from it, in a process known as path integration. This estimate, commonly known as the "home vector," is updated continuously as the ant moves and is reset as soon as it enters its nest, yet ants prevented from returning to their nest can still use their home vector when released several hours later. This conjunction of fast update and long persistence of the home vector memory does not directly map to existing accounts of short-, mid-, and long-term memory; hence, the substrate of this memory remains unknown.

Ocellar spatial vision in Myrmecia ants.

In addition to compound eyes, insects possess simple eyes known as ocelli. Input from the ocelli modulates optomotor responses, flight-time initiation, and phototactic responses - behaviours that are mediated predominantly by the compound eyes. In this study, using pattern electroretinography (pERG), we investigated the contribution of the compound eyes to ocellar spatial vision in the diurnal Australian bull ant Myrmecia tarsata by measuring the contrast sensitivity and spatial resolving power of the ocellar second-order neurons under various occlusion conditions.

Many paths, one destination: mapping the movements of a kleptoparasitic spider on the host's web.

Kleptoparasitic spiders live and forage in the webs of other spiders. Using vibratory cues generated by the host spider during prey capture, they leave their resting positions in the upper peripheries of the host web and move towards the centre of the web where they feed along with the host spider or steal small pieces of prey. While the triggers for initiating the foraging raids are known, there is little information about the fine-scale trajectory dynamics in this model system.

The Antarium: A Reconstructed Visual Reality Device for Ant Navigation Research.

We constructed a large projection device (the Antarium) with 20,000 UV-Blue-Green LEDs that allows us to present tethered ants with views of their natural foraging environment. The ants walk on an air-cushioned trackball, their movements are registered and can be fed back to the visual panorama. Views are generated in a 3D model of the ants' environment so that they experience the changing visual world in the same way as they do when foraging naturally.

Vertical Lobes of the Mushroom Bodies Are Essential for View-Based Navigation in Australian Myrmecia Ants.

Prior to leaving home, insects acquire visual landmark information through a series of well-choreographed walks or flights of learning [1-4]. This information allows them to pinpoint goals both when in their vicinity [5-7] and from locations they have not previously visited [8-10]. It is presumed that animals returning home match memorized views to their current view for successful view-based navigation [11].

The role of attractive and repellent scene memories in ant homing ().

Solitary foraging ants rely on vision when travelling along routes and when pinpointing their nest. We tethered foragers of on a trackball and recorded their intended movements when the trackball was located on their normal foraging corridor (on-route), above their nest and at a location several metres away where they have never been before (off-route). We found that at on- and off-route locations, most ants walk in the nest or foraging direction and continue to do so for tens of metres in a straight line.

Reeling in the prey: fishing behaviour in an orb web spider.

When an insect is intercepted by a spider web, spiders quickly locate the prey and run towards it. Once they make contact with the prey, they immobilise it and retrieve it to the centre of the web or the retreat for consumption. However, in rare circumstances, the spider can also pull the prey towards itself either while running to the prey or from a stationary position, a behaviour termed as 'reeling'.

Ocellar structure of African and Australian desert ants.

Few walking insects possess simple eyes known as the ocelli. The role of the ocelli in walking insects such as ants has been less explored. Physiological and behavioural evidence in the desert ant, Cataglyphis bicolor, indicates that ocellar receptors are polarisation sensitive and are used to derive compass information from the pattern of polarised skylight.

Miniaturisation reduces contrast sensitivity and spatial resolving power in ants.

Vision is crucial for animals to find prey, locate conspecifics and navigate within cluttered landscapes. Animals need to discriminate objects against a visually noisy background. However, the ability to detect spatial information is limited by eye size.

Differential investment in brain regions for a diurnal and nocturnal lifestyle in Australian Myrmecia ants.

Animals are active at different times of the day. Each temporal niche offers a unique light environment, which affects the quality of the available visual information. To access reliable visual signals in dim-light environments, insects have evolved several visual adaptations to enhance their optical sensitivity.

Principles of Insect Path Integration.

Continuously monitoring its position in space relative to a goal is one of the most essential tasks for an animal that moves through its environment. Species as diverse as rats, bees, and crabs achieve this by integrating all changes of direction with the distance covered during their foraging trips, a process called path integration. They generate an estimate of their current position relative to a starting point, enabling a straight-line return, following what is known as a home vector.

The choreography of learning walks in the Australian jack jumper ant .

We provide a detailed analysis of the learning walks performed by ants at the nest during which they acquire visual information on its location Most learning walks of 12 individually marked naïve ants took place in the morning with a narrow time window separating the first two learning walks, which most often occurred on the same day. Naïve ants performed between two and seven walks over up to four consecutive days before heading out to forage. On subsequent walks, naïve ants tend to explore the area around the nest in new compass directions.

Miniaturisation decreases visual navigational competence in ants.

Evolution of a smaller body size in a given lineage, called miniaturisation, is commonly observed in many animals including ants. It affects various morphological features and is hypothesised to result in inferior behavioural capabilities, possibly owing to smaller sensory organs. To test this hypothesis, we studied whether reduced spatial resolution of compound eyes influences obstacle detection or obstacle avoidance in five different species of ants.

The View from the Trees: Nocturnal Bull Ants, , Use the Surrounding Panorama While Descending from Trees.

Solitary foraging ants commonly use visual cues from their environment for navigation. Foragers are known to store visual scenes from the surrounding panorama for later guidance to known resources and to return successfully back to the nest. Several ant species travel not only on the ground, but also climb trees to locate resources.

Techniques for Investigating the Anatomy of the Ant Visual System.

This article outlines a suite of techniques in light microscopy (LM) and electron microscopy (EM) which can be used to study the internal and external eye anatomy of insects. These include traditional histological techniques optimized for work on ant eyes and adapted to work in concert with other techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM). These techniques, although vastly useful, can be difficult for the novice microscopist, so great emphasis has been placed in this article on troubleshooting and optimization for different specimens.

Ocellar structure is driven by the mode of locomotion and activity time in ants.

Insects have exquisitely adapted their compound eyes to suit the ambient light intensity in the different temporal niches they occupy. In addition to the compound eye, most flying insects have simple eyes known as ocelli, which assist in flight stabilisation, horizon detection and orientation. Among ants, typically the flying alates have ocelli while the pedestrian workers lack this structure.

Moving in Dim Light: Behavioral and Visual Adaptations in Nocturnal Ants.

Visual navigation is a benchmark information processing task that can be used to identify the consequence of being active in dim-light environments. Visual navigational information that animals use during the day includes celestial cues such as the sun or the pattern of polarized skylight and terrestrial cues such as the entire panorama, canopy pattern, or significant salient features in the landscape. At night, some of these navigational cues are either unavailable or are significantly dimmer or less conspicuous than during the day.

Polarized light use in the nocturnal bull ant, .

Solitary foraging ants have a navigational toolkit, which includes the use of both terrestrial and celestial visual cues, allowing individuals to successfully pilot between food sources and their nest. One such celestial cue is the polarization pattern in the overhead sky. Here, we explore the use of polarized light during outbound and inbound journeys and with different home vectors in the nocturnal bull ant, .