scholarly journals Nodal and Hedgehog synergize in gill slit formation during development of the cephalochordateBranchiostoma floridae

Development ◽  
2018 ◽  
Vol 145 (15) ◽  
pp. dev162586 ◽  
Author(s):  
Hiroki Ono ◽  
Demian Koop ◽  
Linda Z. Holland
Keyword(s):  
Gill Slit

scholarly journals Evolutionary Relations of Hexanchiformes Deep-Sea Sharks Elucidated by Whole Mitochondrial Genome Sequences

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Keiko Tanaka ◽  
Takashi Shiina ◽  
Taketeru Tomita ◽  
Shingo Suzuki ◽  
Kazuyoshi Hosomichi ◽  
...  
Keyword(s):  
Genetic Relationships ◽  
Close Relation ◽  
Rrna Genes ◽  
Gill Slit ◽  
Mtdna Sequences ◽  
Protein Coding ◽  
Bayesian Phylogenetic Analysis ◽  
Extant Species ◽  
Complete Mitogenome ◽  
Cartilaginous Fishes

Hexanchiformes is regarded as a monophyletic taxon, but the morphological and genetic relationships between the five extant species within the order are still uncertain. In this study, we determined the whole mitochondrial DNA (mtDNA) sequences of seven sharks including representatives of the five Hexanchiformes, one squaliform, and one carcharhiniform and inferred the phylogenetic relationships among those species and 12 other Chondrichthyes (cartilaginous fishes) species for which the complete mitogenome is available. The monophyly of Hexanchiformes and its close relation with all other Squaliformes sharks were strongly supported by likelihood and Bayesian phylogenetic analysis of 13,749 aligned nucleotides of 13 protein coding genes and two rRNA genes that were derived from the whole mDNA sequences of the 19 species. The phylogeny suggested that Hexanchiformes is in the superorder Squalomorphi,Chlamydoselachus anguineus(frilled shark) is the sister species to all other Hexanchiformes, and the relations within Hexanchiformes are well resolved asChlamydoselachus, (Notorynchus, (Heptranchias, (Hexanchus griseus,H. nakamurai))). Based on our phylogeny, we discussed evolutionary scenarios of the jaw suspension mechanism and gill slit numbers that are significant features in the sharks.

scholarly journals Sizing and scarring of whale shark (Rhincodon typus Smith, 1828) in the Cenderawasih Bay National Park

2021 ◽  
Vol 21 (3) ◽  
pp. 199-213
Author(s):  
Yusup A Jentewo ◽  
Roni Bawole ◽  
Tresia S Tururaja ◽  
Mudjirahayu Mudjirahayu ◽  
Zeth Parinding ◽  
...  
Keyword(s):  
National Park ◽  
The Body ◽  
Whale Shark ◽  
Gill Slit ◽  
Rhincodon Typus ◽  
Photo Identification ◽  
Dorsal Fin ◽  
Total Length ◽  
Whale Sharks ◽  
Photo Collection

This study aims to determine the total length and scar condition of the body of whale sharks (Rhincodon typus) in Cendrawasih Bay National Park (TNTC), Papua-Indonesia. Photo-identification was used to identify individuals of the whale shark R. typus based on spot patterns behind the last gill slit of each individual. Photo-identification was also used to determine the scar of the whale shark. The total length of whale sharks were estimated based on the length of a snorkeller (assumed to be 1.6 m) swimming alongside the whale shark. We identified 21 individuals of R. typus. Of these 21 individuals, 14 were new sightings and seven were re-sightings that have been recorded in the previous photo collection database. R. typus ranged in size from 2 to 5 m total length (average 3.78 m, ±0,86, N= 21). Based on their size, all individuals of whale shark were categorized as juvenile. 52% of R. typus identified had scars and 38 % were not and 10% were unknown. The majority of whale sharks had amputation (12 individuals) and abrasion (7 individuals) scars. Scars occurred most often on the caudal fin and dorsal fin, five and four individuals respectively. This information is useful for understanding potential threats and designing better management programmes for R. typus conservation in TNTC.

scholarly journals Sexually Dimorphic Morphological Characters in Five North Atlantic Deepwater Skates (Chondrichthyes: Rajiformes)

2011 ◽  
Vol 2011 ◽  
pp. 1-18 ◽  
Author(s):  
Alexei M. Orlov ◽  
Charles F. Cotton
Keyword(s):  
Sexual Dimorphism ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Morphological Characters ◽  
Sexually Dimorphic ◽  
Gill Slit ◽  
The North ◽  
Disc Width ◽  
Horizontal Diameter ◽  
Mouth Width

Skates exhibit a variety of manifestations of sexual dimorphism. However, this phenomenon has been poorly documented in deepwater species. New data on the sexual dimorphism of five species of deepwater skates from the North Atlantic Ocean are presented:Amblyraja jenseni, Bathyraja pallida, Bathyraja richardsoni, Rajella bigelowi,andR. kukujevi. These skates exhibit sexual dimorphism most frequently in interorbital width, disc length and width, length of the third gill slit, horizontal diameter of the orbit, length of the fifth gill slit, space between the first and fifth gill slits, length of the second dorsal fin base, mouth width, length and width of each lobe of the nasal curtain, distance from the snout to the center of anus, distance from the snout tip to the point of maximum disc width, length of the lateral fold, length of the orbit + spiracle (measured together), tail height at the pelvic fin tips, and the number of median thorns.

scholarly journals Memoirs: The Chorda Tympani and Middle Ear in Reptiles, Birds, and Mammals

1915 ◽  
Vol s2-61 (242) ◽  
pp. 137-160
Author(s):  
EDWIN S. GOODRICH
Keyword(s):  
Facial Nerve ◽  
Middle Ear ◽  
Proximal Region ◽  
Geniculate Ganglion ◽  
Chorda Tympani ◽  
Tympanic Cavity ◽  
Gill Slit ◽  
Lower Region ◽  
Lower Jaw ◽  
Dorsal Edge

A comparison of the development of the various structures of the middle-ear region in the lizard, duck, and mammal, shows a remarkable uniformity in their origin and relation. The first gill-pouch separates off from the epidermis from below upwards; at its dorsal edge is an epiblastic proliferation contributing to the geniculate ganglion. The tympanum is formed between the outer epidermis and an outgrowing diverticulum of the hinder lower region of the first gill-pouch. The chorda tympani is a post-trematic branch of the facial nerve, developing behind the first or spiracular gill-slit, and passing down to the lower jaw between the tympanum and the closing spiracle. The relation of these parts to the skeleton and blood-vessels is (with the exception mentioned below) constant throughout the Amniota, and is only intelligible on the view of Reichert that the proximal region of the columella corresponds to the stapes, the quadrate to the incus, and the articular to the malleus. In the chick the chorda tympani develops as a pre-trematic branch of the facial nerve from its first appearance. In adult gallinaceous birds the chorda passes down directly from the geniculate ganglion in front of the tympanic cavity. This exceptional position is probably due to some secondary modification at present unexplained.

A new genus and species of eelpout (Teleostei: Zoarcidae) from Brazil

Zootaxa ◽  
2008 ◽  
Vol 1852 (1) ◽  
pp. 65 ◽  
Author(s):  
MICHAEL MAIA MINCARONE ◽  
M. ERIC ANDERSON
Keyword(s):  
New Genus ◽  
Southeastern Brazil ◽  
Gill Slit ◽  
New Genus And Species ◽  
Upper Lip ◽  
Caudal Vertebrae ◽  
Fin Rays ◽  
Head Pores ◽  
Janeiro State ◽  
Pelvic Fin

The eelpout Leucogrammolycus brychios gen. et sp. nov., is described from nine specimens, five males (92–198 mm SL) and four females (99–205 mm SL), collected from off Rio de Janeiro state, southeastern Brazil, at depths from 536 to 632 m. It is mainly characterized by the following combination of characters: vertebrae 23–26 + 62–66 = 85–92; first anal-fin pterygiophore associated with first or second caudal vertebrae; scales absent; lateral line with mediolateral and ventral branches; upper lip broadly adnate to snout tip; gill slit not reaching ventrally to opposite lower end of pectoral-fin base; pelvic-fin rays 2; head pores relatively few, small, rounded; and whitish mid-body stripe forming a chevron on top of snout.

The Mechanism of Gill Ventilation in the Dogfish and Skate

1960 ◽  
Vol 37 (1) ◽  
pp. 11-27 ◽  
Author(s):  
G. M. HUGHES
Keyword(s):  
Time Course ◽  
Gill Slit ◽  
Suction Pump ◽  
Pressure Pump ◽  
The Individual ◽  
Triakis Semifasciata ◽  
Leopard Sharks ◽  
Pressure Changes ◽  
Respiratory Movements ◽  
Branchial Region

1. The respiratory movements of the dogfish, Scyliorhinus (Scyllium) canicula (L.), and the ‘skate’, Raia clavata L. (thornback ray), have been studied by the use of cinematographic and mechanotransducer recording methods. Simultaneous determinations of the time-course of pressure changes in the oro-branchial and parabranchial cavities were also made by means of Hansen condenser manometers. 2. In both species movements of the mouth precede those of the spiracular valve and of the branchial region. Adduction and abduction of the branchial region spreads serially from the first to last gill slit in the dogfish, but movements of the individual gill arches are more nearly synchronous in the skate. Opening of the flap valves formed by extensions of the inter-branchial septa are synchronous in both species. 3. Water entering one side of the mouth leaves by the three posterior gill slits of the same side. Water entering the spiracle leaves through the anterior slits of the same side. This separation of flow is less marked in the skate. 4. The pressure curves recorded in all parts of the system have both positive and negative phases with respect to the external medium. The positive phase, associated with closing of the mouth and spiracle, is larger in the oro-branchial than in the parabranchial cavities and vice versa. The time-course of the pressure changes indicates that the flow across the gills is maintained by the action of a pressure pump in front and a suction pump behind. 5. The suction pump plays a more important role than the pressure pump in the skate and its contribution to the flow across the gills is by no means negligible in the dogfish. 6. The differential pressure curves suggest that the flow across the gills is continuous except in the dogfish for a brief period when the gradient is reversed. The absence of this reversal in the skate suggests that the external gill slit openings are controlled by an active mechanism. This is probably an adaptation to bottom-living habit. 7. All these observations relate to animals which are stationary with respect to the water. During swimming at a reasonable speed leopard sharks (Triakis semifasciata) have been observed to make few or no respiratory movements, although they immediately ventilate actively on coming to rest at the bottom of the aquarium.

The distribution and abundance of electrosensory pores in two benthic sharks: a comparison of the wobbegong shark, Orectolobus maculatus, and the angel shark, Squatina australis

2014 ◽  
Vol 65 (11) ◽  
pp. 1003 ◽  
Author(s):  
Channing A. Egeberg ◽  
Ryan M. Kempster ◽  
Susan M. Theiss ◽  
Nathan S. Hart ◽  
Shaun P. Collin
Keyword(s):  
Similar Pattern ◽  
Feeding Behaviour ◽  
Feeding Strategy ◽  
Gill Slit ◽  
Functional Importance ◽  
Aquatic Animals ◽  
Body Form ◽  
Electrosensory System ◽  
Physiological Adaptations

Electroreception is an ancient sense found in many aquatic animals, including sharks, which may be used in the detection of prey, predators and mates. Wobbegong sharks (Orectolobidae) and angel sharks (Squatinidae) represent two distantly related families that have independently evolved a similar dorso-ventrally compressed body form to complement their benthic ambush feeding strategy. Consequently, these groups represent useful models in which to investigate the specific morphological and physiological adaptations that are driven by the adoption of a benthic lifestyle. In this study, we compared the distribution and abundance of electrosensory pores in the spotted wobbegong shark (Orectolobus maculatus) with the Australian angel shark (Squatina australis) to determine whether both species display a similar pattern of clustering of sub-dermal electroreceptors and to further understand the functional importance of electroreception in the feeding behaviour of these benthic sharks. Orectolobus maculatus has a more complex electrosensory system than S. australis, with a higher abundance of pores and an additional cluster of electroreceptors positioned in the snout (the superficial ophthalmic cluster). Interestingly, both species possess a cluster of pores (the hyoid cluster, positioned slightly posterior to the first gill slit) more commonly found in rays, but which may be present in all benthic elasmobranchs to assist in the detection of approaching predators.

scholarly journals Gill slits provide a window into the respiratory physiology of sharks

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Wade J VanderWright ◽  
Jennifer S Bigman ◽  
Cayley F Elcombe ◽  
Nicholas K Dulvy
Keyword(s):  
Metabolic Rate ◽  
Surface Area ◽  
Life Histories ◽  
Extinction Risk ◽  
Order Approximation ◽  
Fork Length ◽  
Respiratory Physiology ◽  
Gill Slit ◽  
Field Guide ◽  
Gill Surface Area

Abstract Metabolically important traits, such as gill surface area and metabolic rate, underpin life histories, population dynamics and extinction risk, as they govern the availability of energy for growth, survival and reproduction. Estimating both gill surface area and metabolic rate can be challenging, especially when working with large-bodied, threatened species. Ideally, these traits, and respiratory physiology in general, could be inferred from external morphology using a faster, non-lethal method. Gill slit height is quick to measure on live organisms and is anatomically connected to the gill arch. Here, we relate gill slit height and gill surface area for five Carcharhiniform sharks. We compared both total and parabranchial gill surface area to mean and individual gill slit height in physical specimens. We also compared empirical measurements of relative gill slit height (i.e. in proportion to total length) to those estimated from field guide illustrations to examine the potential of using anatomical drawings to measure gill slit height. We find strong positive relationships between gill slit height and gill surface area at two scales: (i) for total gill surface area and mean gill slit height across species and (ii) for parabranchial gill surface area and individual gill slit height within and across species. We also find that gill slit height is a consistent proportion of the fork length of physical specimens. Consequently, relative gill slit height measured from field guide illustrations proved to be surprisingly comparable to those measured from physical specimens. While the generality of our findings needs to be evaluated across a wider range of taxonomy and ecological lifestyles, they offer the opportunity that we might only need to go to the library and measure field guide illustrations to yield a non-lethal, first-order approximation of the respiratory physiology of sharks.

Description of Ophthalmolycus andersoni sp. nov. (Pisces, Zoarcidae) from the Antarctic Ocean

Zootaxa ◽  
2009 ◽  
Vol 2027 (1) ◽  
pp. 55-62 ◽  
Author(s):  
JESÚS MATALLANAS
Keyword(s):  
New Species ◽  
Body Shape ◽  
Antarctic Ocean ◽  
Gill Slit ◽  
Pectoral Fin ◽  
Dorsal Fin ◽  
Lateral Branches ◽  
The Antarctic ◽  
A New Species ◽  
Pectoral Fin Rays

A new species of zoarcid fish is described on the basis of three specimens collected from the Antarctic Peninsula, Antarctic Ocean. The new species can be distinguished from its congeners by its body shape and pigment pattern, and by the following combination of characters: 6 branchiostegal rays; pectoral-fin origin well below midbody, pectoral base extending ventrally to abdomen; lateral line double with ventral and medio-lateral branches; oral valve not reaching anterior edge of vomer; gill slit extending ventrally well below end of pectoral fin base; vertebrae asymmetrical 22+7074=92-96; dorsal fin origin associated with vertebrae 4 or 5 with no supraneurals; pectoral fin rays 16 or 17; 2 postorbital pores (positions 1 & 4) and 2 well developed pyloric caeca. The relationships of the new species with its congeners are discussed.

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