Barbara Wueringer

Publications (10) View all

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  Available from: Barbara Wueringer

  Article: Electric field detection in sawfish and shovelnose rays.

  Barbara E Wueringer, Lyle Squire, Stephen M Kajiura, Ian R Tibbetts, Nathan S Hart, Shaun P Collin
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  ABSTRACT: In the aquatic environment, living organisms emit weak dipole electric fields, which spread in the surrounding water. Elasmobranchs detect these dipole electric fields with their highly sensitive electroreceptors, the ampullae of Lorenzini. Freshwater sawfish, Pristis microdon, and two species of shovelnose rays, Glaucostegus typus and Aptychotrema rostrata were tested for their reactions towards weak artificial electric dipole fields. The comparison of sawfishes and shovelnose rays sheds light on the evolution and function of the elongated rostrum ('saw') of sawfish, as both groups evolved from a shovelnose ray-like ancestor. Electric stimuli were presented both on the substrate (to mimic benthic prey) and suspended in the water column (to mimic free-swimming prey). Analysis of around 480 behavioural sequences shows that all three species are highly sensitive towards weak electric dipole fields, and initiate behavioural responses at median field strengths between 5.15 and 79.6 nV cm(-1). The response behaviours used by sawfish and shovelnose rays depended on the location of the dipoles. The elongation of the sawfish's rostrum clearly expanded their electroreceptive search area into the water column and enables them to target free-swimming prey.
  PLoS ONE 01/2012; 7(7):e41605. · 4.09 Impact Factor
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  Available from: Barbara Wueringer

  Article: Electroreception in elasmobranchs: sawfish as a case study.

  Barbara E Wueringer
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  ABSTRACT: The ampullae of Lorenzini are the electroreceptors of elasmobranchs. Ampullary pores located in the elasmobranch skin are each connected to a gel-filled canal that ends in an ampullary bulb, in which the sensory epithelium is located. Each ampulla functions as an independent receptor that measures the potential difference between the ampullary pore opening and the body interior. In the elasmobranch head, the ampullary bulbs of different ampullae are aggregated in 3-6 bilaterally symmetric clusters, which can be surrounded by a connective tissue capsule. Each cluster is innervated by one branch of the anterior lateral line nerve (ALLN). Only the dorsal root of the ALLN carries electrosensory fibers, which terminate in the dorsal octavo-lateral nucleus (DON) of the medulla. Each ampullary cluster projects into a distinctive area in the central zone of the DON, where projection areas are somatotopically arranged. Sharks and rays can possess thousands of ampullae. Amongst other functions, the use of electroreception during prey localization is well documented. The distribution of ampullary pores in the skin of elasmobranchs is influenced by both the phylogeny and ecology of a species. Pores are grouped in distinct pore fields, which remain recognizable amongst related taxa. However, the density of pores within a pore field, which determines the electroreceptive resolution, is influenced by the ecology of a species. Here, I compare the pore counts per pore field between rhinobatids (shovelnose rays) and pristids (sawfish). In both groups, the number of ampullary pores on the ventral side of the rostrum is similar, even though the pristid rostrum can comprise about 20% of the total length. Ampullary pore numbers in pristids are increased on the upper side of the rostrum, which can be related to a feeding strategy that targets free-swimming prey in the water column. Shovelnose rays pin their prey onto the substrate with their disk, while repositioning their mouth for ingestion and thus possess large numbers of pores ventrally around the mouth and in the area between the gills.
  Brain Behavior and Evolution 01/2012; 80(2):97-107. · 2.21 Impact Factor
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  Available from: Barbara Wueringer

  Article: Electroreceptive and Mechanoreceptive Anatomical Specialisations in the Epaulette Shark (Hemiscyllium ocellatum).

  Marit Winther-Janson, Barbara E Wueringer, Jamie E Seymour
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  ABSTRACT: The arrangement of the electroreceptive ampullary system and closely related mechanoreceptive lateral line canal system was investigated in the epaulette shark, Hemiscyllium ocellatum. The lateral line canals form an elaborate network across the head and are continuously punctuated by pores. Ampullary pores are distributed in eleven distinct pore fields, and associated ampullary bulbs are aggregated in five independent ampullary clusters on either side of the head. Pores are primarily concentrated around the mouth and across the snout of the animal. We provide the anatomical basis for future behavioural studies on electroreception and mechanoreception in epaulette sharks, as well as supporting evidence that the electroreceptive ampullary system is specialised to provide behaviourally relevant stimuli. In addition, we describe ampullary pores distributed as far posteriorly as the dorsal fin and thus reject the assumption that ampullary pores are restricted to the cephalic region in sharks.
  PLoS ONE 01/2012; 7(11):e49857. · 4.09 Impact Factor
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  Available from: Barbara Wueringer

  Article: The biology of extinct and extant sawfish (Batoidea: Sclerorhynchidae and Pristidae)

  Barbara Wueringer, Lyle Squire, Shaun Collin
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  ABSTRACT: Sclerorhynchids (extinct sawfishes, Batoidea), pristids (extant sawfish, Batoidea) and pristiophorids (sawsharks, Squalomorphi) are the three elasmobranch families that possess an elongated rostrum with lateral teeth. Sclerorhynchids are the extinct sawfishes of the Cretaceous period, which reached maximum total lengths of 100 cm. The morphology of their rostral teeth is highly variable. Pristid sawfish occur circumtropically and can reach maximum total lengths of around 700 cm. All pristid species are globally endangered due to their restricted habitat inshore. Pristiophorid sawsharks are small sharks of maximum total lengths below 150 cm, which occur in depths of 70–900 m. Close examination of the morphology of pectoral fin basals and the internal structure of the rostrum reveals that sclerorhynchids and pristids evolved independently from rhinobatids, whereas pristiophorids are squalomorph sharks. The elongation of the rostrum may be an adaptation for feeding, as all marine vertebrate taxa that possess this structure are said to use it in the context of feeding.
  Reviews in Fish Biology and Fisheries 05/2009; 19:445-464. · 2.50 Impact Factor
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  Available from: Barbara Wueringer

  Article: The function of the sawfish's saw.

  Barbara E Wueringer, Lyle Squire, Stephen M Kajiura, Nathan S Hart, Shaun P Collin
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  ABSTRACT: Jawed fishes that possess an elongated rostrum use it to either sense prey or to manipulate it, but not for both. The billfish rostrum, for instance, lacks any sensory function and is used to stun prey [1], while paddlefishes use their rostrum to detect and orient towards electric fields of plankton [2]. Sturgeons search through the substrate with their electroreceptive rostrum, and engulf prey by oral suction [2]. Here, we show that juvenile freshwater sawfish Pristis microdon are active predators that use their toothed rostrum - the saw - to both sense prey-simulating electric fields and capture prey. Prey encountered in the water column is attacked with lateral swipes of the saw that can stun and/or impale it. We compare sawfish to shovelnose rays, which share a common shovelnose ray-like ancestor [3] and lack a saw.
  Current biology: CB 03/2012; 22(5):R150-1. · 10.99 Impact Factor