Mechanisms of homing in the fiddler crab<i>Uca rapax</i>2. Information sources and frame of reference for a path integration system

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SUMMARYFiddler crabs are intertidal brachyuran crabs that belong to the genus Uca. Approximately 97 different species have been identified, and several of these live sympatrically. Many have species-specific body color patterns that may act as signals for intra-and interspecific communication. To understand the behavioral and ecological role of this coloration we must know whether fiddler crabs have the physiological capacity to perceive color cues. Using a molecular approach, we identified the opsinencoding genes and determined their expression patterns across the eye of the sand fiddler crab, Uca pugilator. We identified three different opsin-encoding genes (UpRh1, UpRh2 and UpRh3). UpRh1 and UpRh2 are highly related and have similarities in their amino acid sequences to other arthropod long-and medium-wavelength-sensitive opsins, whereas UpRh3 is similar to other arthropod UV-sensitive opsins. All three opsins are expressed in each ommatidium, in an opsin-specific pattern. UpRh3 is present only in the R8 photoreceptor cell, whereas UpRh1 and UpRh2 are present in the R1-7 cells, with UpRh1 expression restricted to five cells and UpRh2 expression present in three cells. Thus, one photoreceptor in every ommatidium expresses both UpRh1 and UpRh2, providing another example of sensory receptor coexpression. These results show that U. pugilator has the basic molecular machinery for color perception, perhaps even trichromatic vision.

Section: Spatial Distribution Of U Pugilator Opsinsmentioning

confidence: 99%

Molecular evidence for color discrimination in the Atlantic sand fiddler crab, Uca pugilator

Rajkumar

Rollmann

Cook

et al. 2010

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“…Despite the current lack of comparative data on modulating velocity between a start and stop, systems such as the predatory attacks of suction-feeding fishes and fiddler crabs returning to their home burrows (Layne et al, 2003) may prove to be useful model systems for future investigation of starts and stops in which experimenters can manipulate distance and have animals come to a stop at a predictable location.…”

Section: Ecological Relevance Of Stoppingmentioning

confidence: 99%

Constraints on starting and stopping: behavior compensates for reduced pectoral fin area during braking of the bluegill sunfishLepomis macrochirus

Higham

Malas

Jayne

et al. 2005

SUMMARY Many natural animal movements involve accelerating from a standstill and then stopping. Obstacles in natural environments often limit the straight-line distance available for movement, and decreased braking ability theoretically can limit speed for short distances. Consequently, braking ability can be important for avoiding collisions with obstacles and exploiting resources effectively in complex environments. A presumed morphological correlate of improved braking performance in fish is increased pectoral fin area, because most fish protract these structures as they decelerate. However, the kinematics and modulation of velocity during starting and stopping are poorly understood for most species of fish as well as most species of animals. Thus,for bluegill sunfish Lepomis macrochirus with complete and partially ablated pectoral fins (35% original fin area), we analyzed high speed video recordings (200 images s–1) of predatory attacks with a start and stop in a short, standardized distance (40 cm). We quantified body displacement, velocity, acceleration, deceleration and several fin angle variables during each feeding. Unexpectedly, several variables including maximum velocity and maximum deceleration (grand means 72 cm s–1 and –512 cm s–2, respectively) did not change significantly with reduced pectoral fin area. The average values of braking movements of the median and caudal fins did increase with decreased pectoral fin area but lacked statistically significant differences. The primary mechanism of attaining similar braking performance with decreased area of the pectoral fins was that they were protracted significantly more (mean difference=42°) and with a significantly faster average velocity of protraction. Thus, pectoral fin area appears unlikely to be the primary constraint on braking performance for this particular task.

“…However, it is becoming increasingly apparent that despite their relatively small brains and generally shorter distances traveled (the monarch butterfly, Danaus plexippus, not withstanding; Mouritsen et al, 2013), many arthropod species also display an impressive navigational ability (Cheng, 2012;Collett and Graham, 2004;Boles and Lohmann, 2003;Layne et al, 2003). Indeed, both honey bees (Apis mellifera; Menzel et al, 2005) and an Australian ant species (Myrmecia croslandi; Narendra et al, 2013) have been shown to be able to return to their nests even after experimental displacement to unfamiliar locations, suggesting a cognitively rich navigational capacity.…”

Section: Introductionmentioning

confidence: 99%

Importance of the antenniform legs, but not vision, for homing by the neotropical whip spider,Paraphrynus laevifrons

Bingman

Graving

Hebets

et al. 2016

Amblypygids, or whip spiders, are nocturnal, predatory arthropods that display a robust ability to navigate to their home refuge. Prior field observations and displacement studies in amblypygids demonstrated an ability to home from distances as far away as 10 m. In the current study, micro-transmitters were used to take morning position fixes of individual Paraphrynus laevifrons following an experimental displacement of 10 m from their home refuge. The intention was to assess the relative importance of vision compared with sensory input acquired from the antenniform legs for navigation as well as other aspects of their spatial behavior. Displaced individuals were randomly assigned to three treatment groups: (i) control individuals; (ii) visiondeprived individuals, VD; and (iii) individuals with sensory input from the tips of their antenniform legs compromised, AD. Control and VD subjects were generally successful in returning home, and the direction of their movement on the first night following displacement was homeward oriented. By contrast, AD subjects experienced a complete loss of navigational ability, and movement on the first night indicated no hint of homeward orientation. The data strongly support the hypothesis that sensory input from the tips of the antenniform legs is necessary for successful homing in amblypygids following displacement to an unfamiliar location, and we hypothesize an essential role of olfaction for this navigational ability.