V.—<i>The Lateral Sense Organs of Elasmobranchs</i>. I. <i>The Sensory Canals of Læmargus</i>

Ewart, J. C.

doi:10.1017/s0080456800032518

Cited by 19 publications

(13 citation statements)

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“…In D. sabina only dorsolateral pit organs appeared to be present, while R. eglanteria also possessed supratemporal pit organs and an ad- ditional discrete group of pit organs immediately ventral to the eye. A similar group of pit organs, in the region of the eye and/or spiracle, was also noted in a few other skates and bottom-dwelling (demersal) sharks (Ewart, 1892;Ewart and Mitchell, 1892;Budker, 1938;Tester and Nelson, 1967;Disler, 1977;Fulgosi and Gandolfi, 1983). This group of pit organs was not named in previous review articles, but it will be referred to here as the "spiracular group" of pit organs.…”

supporting

confidence: 53%

“…The positions of various other pit organ groups with respect to nearby canals were not recorded here, as the canals were less clearly stained than the surface organs. Pit organ distribution with respect to the canals, however, is reasonably well known from other studies (Ewart, 1892;Ewart and Mitchell, 1892;Johnson, 1917;Ruud, 1920;Tester andKendall, 1967, 1969;Tester and Nelson, 1967;Disler 1977;Maruska and Tricas, 1998;Maruska, 2001).…”

Section: Discussionmentioning

confidence: 52%

“…Some observations of pit organ distribution in whole shark embryos (Allis, 1902;Ruud, 1920;Petit and Budker, 1936a,b), or on portions of the body surface (Ewart, 1892;Ewart and Mitchell, 1892;Norris and Hughes, 1920;Daniel, 1934) can be found in early studies of the lateral line, but the complete postembryonic distribution of pit organs on the body surface is recorded for just 23 speciesonly about 2% of extant elasmobranch species (Johnson, 1917;Budker, 1938Budker, , 1944Tester and Nelson, 1967;Disler, 1977;Fulgosi and Gandolfi, 1983;Reif, 1982;Maruska and Tricas, 1998;Maruska, 2001). As 12 of these are closely related carcharhiniform sharks (including the carcharhinids, sphyrnids, triakids, and hemigaleids; summarized in Table 1), they can hardly be considered a representative sample of elasmobranchs.…”

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confidence: 99%

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Inter‐ and intraspecific variation in the distribution and number of pit organs (free neuromasts) of sharks and rays

Peach

2003

Journal of Morphology

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The distribution of pit organs (free neuromasts) has previously been documented for several species of pelagic sharks, but is relatively poorly known for rays and bottom-dwelling (demersal) sharks. In the present study, the complete distribution of pit organs was mapped in the demersal sharks Heterodontus portusjacksoni, Orectolobus maculatus, Hemiscyllium ocellatum, Chiloscyllium punctatum, and Asymbolus analis, and the rays Rhinobatos typus, Aptychotrema rostrata, Trygonorrhina sp. A, Raja sp. A, and Myliobatis australis. All of these species had pit organs scattered over the dorsolateral surface. The sharks also had "mandibular" pit organs (and "umbilical" pit organs in C. punctatum and A. analis) on the ventral surface, while pit organs were sparse or absent on the ventral surface of rays. All of the species examined here, except for M. australis, also had a "spiracular" group of pit organs adjacent to the eye and/or spiracle. Spiracular pit organs were also recorded for the sawshark Pristiophorus sp. A and the skate Pavoraja nitida, although the remainder of pit organs were not mapped in these species. The distribution and number of pit organs varied both within and among species. Pit organ distribution was asymmetrical in each individual examined, but no particular trend towards left or right "handedness" was observed in any species. Although rays have been thought to have fewer pit organs than sharks in general, this was not the case in the present study. All of the species examined here had few pit organs compared to the pelagic sharks previously documented, but it is not clear whether this is due to ecological or phylogenetic causes.

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confidence: 53%

Section: Discussionmentioning

confidence: 52%

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Inter‐ and intraspecific variation in the distribution and number of pit organs (free neuromasts) of sharks and rays

Peach

2003

Journal of Morphology

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“…Comparison of the electroreceptive system of H. ocellatum and C. plagiosum with species studied by Ewart [48] allows speculation on the innervation of the clusters identified in H. ocellatum . We propose that cluster one represents the supraorbital cluster; cluster two represents the inner buccal cluster; cluster three represents the outer buccal cluster; cluster four represents the hyoidean cluster and cluster five represents the mandibular cluster.…”

Section: Discussionmentioning

confidence: 99%

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

2012

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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.

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“…The complete distribution of pit organs in embryonic and postembryonic specimens is recorded for 32 species – about 3% of the extant elasmobranchs (Allis 1902; Johnson 1917; Ruud 1920; Petit and Budker 1936a,b; Budker 1938, 1944; Tester and Nelson 1967; Disler 1977; Fulgosi and Gandolfi 1983; Reif 1985; Maruska and Tricas 1998; Maruska 2001; Peach 2003). In addition, detailed illustrations of pit organs on isolated portions of the body surface are available for several taxa (Ewart 1892; Ewart and Mitchell 1892; Norris and Hughes 1920; Daniel 1934; Disler 1977; Peach 2003). It is clear that patterns of pit organ distribution and abundance vary considerably among taxa, but the ecological and evolutionary implications of this variation have not been examined in any detail.…”

Section: Introductionmentioning

confidence: 99%

Phylogenetic trends in the abundance and distribution of pit organs of elasmobranchs

Peach

Rouse

2004

Acta Zoologica

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 Abstract Peach, M.B and Rouse, G.W. 2004. Phylogenetic trends in the abundance and distribution of pit organs of elasmobranchs. -Acta Zoologica (Stockholm) 85 : 233-244Pit organs (free neuromasts of the mechanosensory lateral line system) are distributed over the skin of elasmobranchs. To investigate phylogenetic trends in the distribution and abundance of pit organs, 12 relevant morphological characters were added to an existing matrix of morphological data (plus two additional end terminals), which was then re-analysed using cladistic parsimony methods (  * 4.0b10). Character transformations were traced onto the most parsimonious phylogenetic trees. The results suggest the following interpretations. First, the distinctive overlapping denticles covering the pit organs in many sharks are a derived feature; plesiomorphic elasmobranchs have pit organs in open slits, with widely spaced accessory denticles. Second, the number of pit organs on the ventral surface of rays has been reduced during evolution, and third, spiracular pit organs have changed position or have been lost on several occasions in elasmobranch evolution. The concentrated-changes test in  (version 4.05) was used to investigate the association between a pelagic lifestyle and loss of spiracular pit organs (the only character transformation that occurred more than once within pelagic taxa). Depending on the choice of tree, the association was either nonsignificant at P = 0.06 or significant at P < 0.05. Future studies, using species within more restricted elasmobranch clades, are needed to resolve this issue.

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V.—The Lateral Sense Organs of Elasmobranchs. I. The Sensory Canals of Læmargus

Cited by 19 publications

References 3 publications

Inter‐ and intraspecific variation in the distribution and number of pit organs (free neuromasts) of sharks and rays

Inter‐ and intraspecific variation in the distribution and number of pit organs (free neuromasts) of sharks and rays

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

Phylogenetic trends in the abundance and distribution of pit organs of elasmobranchs

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