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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Study on the reproduction of Paramyxine nelsoni (Myxinidae)from the southwestern coast of Taiwan

Hung, Li-Yueh 12 February 2003 (has links)
This study investigates the reproductive biology of Paramyxine nelsoni which distributes in some areas off the southwestern coast of Taiwan. Specimens were captured by shrimp traps. Body weight and body length were measured. Maturation stages of female, adult male and immature were recored. Egg length¡Bnumber of egg, gonad weight and GSI for mature females were measured. Results showed that P. nelsoni spawned all year round. However, a drastic increase of GSI in June and a drop in July, was noticed suggesting that reproduct in summer. Sex ratio was female¡Gmale¡Gimmature = 0.68¡G0.20¡G0.11; male/female = 0.30 . Number of females was fewer in July, suggersting a possibility that female foraging activity reduce after spawning. The minimum maturature sizes for both sexes were 16 cm. The maximum size of female was larger than that of male. Results showed that P. nelsoni is not proatndrous. Small female smaller than 20 cm did not contained eggs longer than 3 mm. Some of females longer than 20 cm might involve in spawning activity. According to the frequency distribution of egg length, it was confirmed that P. nelsoni were synchronous spawner and reproduct iteroparous. Eggs were in one to two discontinuous size classes. Mature females produced only 3-7 ripe eggs at a time. Anchor-like hooks appeared in both tipa of 20~27 mm eggs. Mechanism controlling the development of these hooks remains unclear.
2

A histological study on the inner ear of the hagfish Paramyxine nelson with special reference to the statoconia morphology

Lee, Yi-Hsin 08 August 2002 (has links)
The agnathan hagfish is the plesiomorphic sister group of vertebrates. It is eel-liked, cartilaginous, and has only one semicircular canal. As hagfish have no hard structures that age determination remains unsuccessful. In the present work, we examined the statoconia in the inner ear of the hagfish Paramyxine nelsoni intense to explore it as a useful index in hagfish¡¦s age determination. P. nelsoni is quite abundant at some localities in the southwestern coast of Taiwan. Due to its smaller size, P. nelsoni is not a commercial species in this area. Little information on its populations is available in the literature. Consequently P. nelsoni is a potential model species for fisheries study of hagfish. The statoconia of the P. nelsoni were deciphered from 49 specimens with body length ranging from 10.2cm to 29.5cm. The semicircular canals were examined using scanning electron microscope. Histological sections for the semicircular canals were also made for observation of cytological characters. The masses of statoconia were located on the surface of the macular epithelium. The epithelium of macula was psudostratified columnar type, which was composed of hair cells and supporting cells. Diameters of the statoconia were ranged from 1 &#x00B5;m to 26 &#x00B5;m (3.41¡Ó 0.29 &#x00B5;m). Most of them were distributed in a narrow range from 4 &#x00B5;m to 8 &#x00B5;m. Both small (<4£gm) and large (>8£gm) statoconia were observed in all size of Paramyxine nelsoni. The diameter of statoconia was not correlated with body length. Although the numbers of statoconia were increased with body length, it was not separate clearly between each body size. The shape index (short diameter/long diameter) was decreased when the long diameters of statoconia were larger than 6 &#x00B5;m. This result suggests that statoconia are produced to accumulate from round to ellipse throughout hagfish¡¦s life span. In conclusion, both of the diameters and numbers of statoconia may not be appropriate index in age determination of hagfish.
3

Proteometabolomics of Hagfish Cardiac and Skeletal Muscles

Chiu, Kuo-hsun 31 July 2008 (has links)
Hagfish are the plesiomorphic sister group of all vertebrates. They are scavengers and many live at depths reaching thousands of meters. In addition, hagfish show the lowest metabolic rate as well as cardiac performance in vertebrates. This dissertation evaluated the biochemical characterizations of hagfish skeletal muscles related to the feeding apparatus and hagfish cardiac muscle associated with cardiac performance and deep-sea effects at the proteomic and metabolomic levels. In Chapter one and two, I found creatine kinase over-expressed in hagfish somatic muscle and deep-sea hagfish cardiac muscle, I suppose that this enzyme was important for utilization of stored phosphocreatine in deep-sea animals¡¦ somatic muscle and cardiac muscle. Over-expressed glycogen phosphorylase in hagfish dental and deep-sea hagfish cardiac muscle supposes these two types of muscles undergoing the anaerobic glycolysis. Compared to teleosts (cobia and tuna), TMAO and urea were higher in hagfish suggest their functions in hagfish cardiac muscle as osmolytes, however, higher TMAO but not urea in deep-sea hagfish, I suggest TMAO functions not only as an osmolyte but also physiological impacts in hagfish cardiac muscle for depth-related adaptations. I also found higher nebulin express in hagfish cardiac muscle and higher tropomyosin express in cobia and tuna cardiac muscles, thus their contractile differentiations were resulted from the protein-protein mechanism. This dissertation provides candidate proteins and metabolits involved in ecophysiological adaptation of hagfish skeletal and cardiac muscles.
4

On The Reproduction of Hagfish, Paramyxine cheni (Myxinidae) from Taiwan

chua, wooi-min 21 July 2004 (has links)
Abstract The Taiwanese hagfish Paramyxine cheni (Myxidae) is believed as a primitive species in the Eptatretinae and it distributes on the west south coast of Taiwan. Hagfishes are noteworthy to study from an evolutionary standpoint because they represent the oldest extant clade among the craniates. A better understanding of their reproductive states may thus reveal information for fisheries management. This research presents data on size, weight, GSI (Gonadosomatic Index), HSI ( Hepatosomatic index) and reproductive states for specimens collected at a study site (22¢X22¡¦43¡¨N, 120¢X14¡¦92¡¨E) near Tong-kung, Southern Taiwan. Specimens were collected once a months from December 2002 through November 2003 for body weight, body length, gonad weight, liver weight and liver lipid content. GSI, show that the P.cheni had a seasonal reproduction period in April and May. HSI data also show a positive correlation with GSI. The sex ratio among the female, male and sex undeterminated individuals was 0.51¡G0.20¡G0.29. The maximum body length was 55.9cm, and smallest body length was 9.5cm. I define the full maturity as appearance of the mushroom-like structure at the tips of the egg. P.cheni matured around 40cm. Gonad developed at 18.5cm body length, when minute eggs observable by naked eye are present. Lipids distribution in liver was significantly different in female before and after the reproduction period; lipid cells were more condense in the former period. Color of liver difference between the male and female P.cheni; male¡¦s liver was more reddish. Therefore, before sex differentiation, I can identify the sex of an individual by the color of its liver.
5

Venous control in a primitive fish Eptatretus cirrhatus

Anstiss, Julie January 2005 (has links)
Only a small amount of the available literature is concerned with venous control in lower vertebrates, such as fish. It has even been suggested that veins in fish are not important factors in active regulation of venous return. Preliminary work carried out for this thesis strongly refuted this assumption, highlighting gaps in the existing literature. As a result of the lack of information pertaining to the physiology of the central venous compartment of the circulation, my objective has been to investigate various aspects of this in the hagfish Eptatretus cirrhatus. Hagfishes, with the lowest arterial blood pressures and highest blood volumes amongst the chordates, are the earliest surviving group to separate off from the chordate lineage. They provide a unique opportunity to investigate likely physiological mechanisms in ancestral chordates. The data presented in this thesis suggest thtat 1) E. cirhatus exhibit some cardiovascular compensation during volume manipulation, however this only occurs with volume loading and not during volume depletion, 2) Veins from E. cirrhatus can respond vasoactively to adrenergic stimulation in vitro and 3) Plasma catecholamines in E. cirrhatus also respond to volume manipulation and provide a potential in vivo mechanism for the control of changes in cardiovascular parameters that were observed during volume loading.
6

Venous control in a primitive fish Eptatretus cirrhatus

Anstiss, Julie January 2005 (has links)
Only a small amount of the available literature is concerned with venous control in lower vertebrates, such as fish. It has even been suggested that veins in fish are not important factors in active regulation of venous return. Preliminary work carried out for this thesis strongly refuted this assumption, highlighting gaps in the existing literature. As a result of the lack of information pertaining to the physiology of the central venous compartment of the circulation, my objective has been to investigate various aspects of this in the hagfish Eptatretus cirrhatus. Hagfishes, with the lowest arterial blood pressures and highest blood volumes amongst the chordates, are the earliest surviving group to separate off from the chordate lineage. They provide a unique opportunity to investigate likely physiological mechanisms in ancestral chordates. The data presented in this thesis suggest thtat 1) E. cirhatus exhibit some cardiovascular compensation during volume manipulation, however this only occurs with volume loading and not during volume depletion, 2) Veins from E. cirrhatus can respond vasoactively to adrenergic stimulation in vitro and 3) Plasma catecholamines in E. cirrhatus also respond to volume manipulation and provide a potential in vivo mechanism for the control of changes in cardiovascular parameters that were observed during volume loading.
7

Reproductive biology and ecology of Pacific hagfish (Eptatretus stoutii) and Black hagfish (Eptatretus deani) off the coast of Vancouver Island, BC

Fleury, Aharon 08 September 2016 (has links)
Hagfish are one of the more lucrative commercial opportunities in the world with fisheries harvesting them specifically for food and for their skin for leather-based products. In 2013 a three year experimental fishery opened off the west coast of Vancouver Island, British Columbia in order to determine the sustainability of a Pacific hagfish (Eptatretus stoutii) and Black hagfish (Eptatretus deani) fishery. In this study, I examined the reproductive biology of both species including: length-weight relationships, sex ratios, fecundity, and size-at-gonadal development. This study corroborates previous suggestions that Pacific hagfish are juvenile protogynous hermaphrodites while black hagfish are likely to be dioecious with an unknown juvenile stage. Sexual dimorphism appears in both species of hagfish, which is likely the result of inter- and intraspecific morphological differences. For both species fecundity decreases throughout developmental stages, and the average fecundity is very low (27-32 eggs per female). Additionally, in both species females commence gonadal development prior to males. Furthermore, both species exhibited extreme female: male sex ratios across length-classes, however, in opposite directions. The reproductive biology of Pacific and Black hagfish models that of a k-selected species, which is a species that tends to live long and has a slow growth rate, low fecundity, and late maturity. As a result there are a variety of concerns that should be addressed when developing a sustainable hagfish fishery to prevent collapses observed in previous hagfisheries. / Graduate / 2017-08-23
8

Kinematics and Hydrodynamics of Undulatory Locomotion in Hagfishes (Myxinidae) and Hagfish-like Robotic Models

Lim, Jeanette Li Li 30 September 2013 (has links)
Hagfishes have both intrigued and confused biologists since Linnaeus first mistakenly classified one as an "intestinal worm." Modern hagfishes (Myxinidae) are elongate, marine fishes often described by what they lack: jaws, scales, paired fins, or a vertebral column. Accompanying this reduced morphology was a long-held view that hagfish are lazy animals that mostly lay about on the ocean floor, but more recent research has revealed them to be active hunters and scavengers in the benthic community. Routine swimming is a requisite part of these activities, yet knowledge of how these exceptionally flexible fishes swim is limited. Here, I use an integrative experimental approach to provide a more comprehensive, quantitative understanding of locomotory mechanisms in hagfishes. In Chapters 1 and 2, I use high-speed videography to quantify whole-body kinematics of steady and unsteady swimming in Eptatretus stoutii and Myxine glutinosa, representing the two main lineages within Myxinidae. Both species generally swim with high amplitude head movements and use tail beat frequency to control swim speed, but inter- and intra-specific variation in other undulatory wave variables suggests multiple mechanisms to modulate speed. Changes in the shape of the body wave characterize the observed unsteady swimming behaviors. During positive linear accelerations, hagfish transiently adopt a larger, longer body wave. During lateral maneuvers, hagfish approximate “sidewinding” behavior as anterior body regions interact with the substrate while posterior body regions propagate waves of lateral bending toward the tail tip. Chapter 3 integrates kinematics with hydrodynamics, using particle image velocimetry to visualize the flow field around swimming E. stoutii. The steady swimming wake consists of caudolateral fluid jets, which turn caudally during linear accelerations. Wake jets orient asymmetrically during lateral swimming, contributing both forward and lateral thrust over a complete tail beat. The hydrodynamic patterns observed reinforce kinematics-based hypotheses on how hagfishes enact their various swimming behaviors. In Chapter 4, I use simple robotically-controlled physical models to examine functional relationships between body flexural stiffness, shape, kinematics, hydrodynamics, and swimming performance. I relate model swim performance to characteristics of hagfish swimming, and describe lessons that passively undulating models impart for understanding locomotion by live elongate undulatory swimmers.
9

The behavior response to light and distribution of the photo-sensitive pigment in Paramyxine cheni (Myxinidae)

Chin, Shen-hui 05 February 2006 (has links)
The objectives of this study are to know the behavioural response of the hagfish, Paramyxine cheni to light and to find out if various parts of hagfish¡¦s body differ in sensitivity to light. Photosensitivity was measured in terms of time lapsed between light on and initiation of behavioural sequence (i.e., the reactive time). Behavioral response was measured by the persistent time from the beginning and ending of the behavioural sequence. Five types of light were used as the stimuli to the whole animal: green light, blue light, yellow light, red light, and white light. The lineup of sensitivity for various wavelengths in increasing reactive times( ranging from 13 seconds to 180 seconds) is: green light, blue light, white light, yellow light, red light. Red light significantly differed from the other four types of light in the reactive time; the hagfish was significantly less sensitive to this red light. Four regions of the body were tested with white light: head, gill aperture, tail and mid-portion between the first gill aperture to cloaca. In addition, two parts of the body were simultaneous tested with stimulate: head and tail (HT). The lineup of sensitivity of various regions of body for increasing reactive times (ranging from 9 seconds to 1200 seconds) is: tail, head, mid-portion between the first gill aperture to cloaca, and gill aperture. Tail was significantly more sensitive than the other three parts of the body. However, sensitivity for HT was significantly higher than the tail. Hagfish¡¦s spontaneous movement (i.e., under dark condition)included a number of behavioural sequences differed in the arrangement of behavior patterns (i.e., rolling, swimming, wiggling, springing, and pause). ¡¥Rolling¡¦ was the most preferred initial pattern in a spontaneous movement sequence. In contrast, illumination on tail evoked a complex motor response. Thus, such response was considered not a simple reflex, but a select of choice. ¡¥Swimming¡¦, on the other hand, is the most preferred initial pattern in the sequence triggered by photo stimulation on the tail. According to fluoresence histochemistry study the rhodopsin-like protein is present in the large oval-shaped cells distributed in the epidermis of hagfish. the number and the size of photo-sensitive cells on the tail and gill aperture and the fluorescence intensity on the tail were significantly higher than that on the gill aperture region.
10

Comparative Analysis of the Anatomy of the Myxinoidea and the Ancestry of Early Vertebrate Lineages

Miyashita, Tetsuto Unknown Date
No description available.

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