Mouthparts of Tarsonemus nodosus Schaarschmidt, 1959 (Acari: Tarsonemidae): fine structure and functional morphology

2002 ◽  
pp. 269-281 ◽  
Author(s):  
G. Nuzzaci ◽  
A. Di Palma ◽  
W. L. Magowski ◽  
P. Aldini
Keyword(s):  
Fine Structure ◽  
Functional Morphology

The Biology of Bothrimonus (=Diplocotyle) (Pseudophyllidea: Cestoda): Detailed Morphology and Fine Structure

1974 ◽  
Vol 31 (2) ◽  
pp. 147-153 ◽  
Author(s):  
M. D. B. Burt ◽  
I. M. Sandeman
Keyword(s):  
Electron Microscopy ◽  
Nervous System ◽  
Fine Structure ◽  
Functional Morphology ◽  
Light And Electron Microscopy ◽  
Nerve Fibers ◽  
Fish Host ◽  
Extensive System ◽  
And Function

Light and electron microscopy were used to describe the functional morphology of Bothrimonus sturionis in detail. In particular, the musculature, nervous system, osmoregulatory system, and tegument are dealt with, and the findings compared with those of other workers. The musculature of the scolex consists of several interrelated systems, the structure of each being discussed in relation to its function. Associated with the regular nervous system, considered typical of cestodes, is an extensive system of giant nerve fibers. The osmoregulatory system is unusual in that there are lateral "excretory" pores in many proglottides which open directly to the exterior of the worm. The microtriches of the tegument are long, like those of other primitive cestodes, and are covered by a noncellular sheath while the worm is in its gammarid host. The sheath is lost when the worm becomes established in its fish host; the nature and function of the sheath are discussed.

scholarly journals Cellular morphology of leg musculature in the water bear Hypsibius exemplaris (Tardigrada) unravels serial homologies

2019 ◽  
Vol 6 (10) ◽  
pp. 191159 ◽  
Author(s):  
Vladimir Gross ◽  
Georg Mayer
Keyword(s):  
Fine Structure ◽  
Functional Morphology ◽  
Cellular Structure ◽  
Evolutionary History ◽  
Ancestral State ◽  
Leg Muscles ◽  
Open Questions ◽  
Attachment Sites ◽  
Functional Implications ◽  
Water Bears

Tardigrades (water bears) are microscopic, segmented ecdysozoans with four pairs of legs. Lobopodous limbs that are similar to those seen in tardigrades are hypothesized to represent the ancestral state of Panarthropoda (Tardigrada + Onychophora + Arthropoda), and their evolutionary history is important to our understanding of ecdysozoan evolution. Equally important is our understanding of the functional morphology of these legs, which requires knowledge of their musculature. Tardigrade musculature is well documented but open questions remain. For example, while the muscular organization of each trunk segment and its legs is unique, three of the four trunk segments are nevertheless relatively homonomous. To what extent, then, do leg muscles show segmental patterns? Specifically, which leg muscles are serially repeated and which are unique? The present study addresses these questions using a combination of techniques intended to visualize both the overall layout and fine structure of leg muscles in the eutardigrade Hypsibius exemplaris . In doing so, we propose serial homologies for all leg muscles in each of the four legs and reveal new details of their cellular structure and attachment sites. We compare our results to those of previous studies and address the functional implications of specialized muscle cell morphologies.

Fine Structure and Functional Morphology of the Spermatodactyl in Males of Heterozerconidae (Gamasida)

2008 ◽  
Vol 34 (4) ◽  
pp. 359-366 ◽  
Author(s):  
Antonella Di Palma ◽  
Beverly S. Gerdeman ◽  
Gerd Alberti
Keyword(s):  
Fine Structure ◽  
Functional Morphology

Ultrastructural studies of the elytra of Pholoe minuta (Annelida: Polychaeta) with special reference to functional morphology

1990 ◽  
Vol 70 (3) ◽  
pp. 545-556 ◽  
Author(s):  
P. Heffernan
Keyword(s):  
Fine Structure ◽  
Special Reference ◽  
Functional Morphology ◽  
Morphological Study ◽  
Sensory Perception ◽  
Ultrastructural Level ◽  
Gaseous Exchange ◽  
Polychaete Species ◽  
Water Currents ◽  
Ultrastructural Studies

It has been suggested by Pettibone (1953) and Lwebuga-Musaka (1970) that the elytra of scaleworms may function in respiration, not as the sites of gaseous exchange, but rather the means by which respiratory water currents were created over the dorsum. A role in sensory perception was also postulated (Pettibone, 1953). However, no detailed morphological study accompanied this work. To date the scales of only a few polychaete species have been examined ultrastructurally, and these studies have focused mostly on cuticular features (Anton-Erxleben, 1977, 1981a, b). Considerable attention has been focused on the bioluminescent properties of the elytra of the scaleworm, Harmothoe lunulata (Delle Chiaje) (see Bassot, 1979; Nicholas et al. 1981, 1982). Other morphological features of Pholoe minuta studied at the ultrastructural level include gametogenic (Heffernan & Keegan, 1988a) and larval (Heffernan & Keegan, 1988b) stages as well as the digestive tract (Heffernan, 1988). There are several reports on the ultrastructure of polychaete gills (Storch & Welsch, 1972; Spies, 1973; Storch & Alberti, 1978; Menendez et al., 1984; Storch & Gaill, 1986). These works have recently been reviewed by Gardiner (1988). This study describes the fine structure of the scales of Pholoe minuta and the features illustrated here are in agreement with a role in respiration and sensory perception.

Observations on the movements and structure of the bursa of Nippostrongylus brasiliensis and Nematospiroides dubius

1976 ◽  
Vol 54 (9) ◽  
pp. 1466-1480 ◽  
Author(s):  
N. A. Croll ◽  
K. A. Wright
Keyword(s):  
Fine Structure ◽  
Functional Morphology ◽  
The Body ◽  
Pacemaker Activity ◽  
Nippostrongylus Brasiliensis ◽  
Control Mechanisms ◽  
Genital Cone ◽  
Organ Systems ◽  
Nematospiroides Dubius

There is growing evidence of the autonomy of the movements of certain organ systems in nematodes. The copulatory bursa of male strongylines is believed to aid in mating, although there arc very few reports of this. Furthermore, it has been suggested that movements of the bursa are stimulated by a pheromone secreted by the female. Bursal movements were investigated with respect to these themes and the fine structure of the bursa of Nippostrongylus brasiliensis was examined. When the bursa was ligatured and isolated from the body, bursal movements of N. brasiliensis and Nematospiroides dubius were greatly increased for extended periods. The movements showed rhythmic pacemaker activity and they simulated the movements observed in the normal mating of N. dubius. The bursa of N. brasiliensis was found to have muscular and sensory elements, a nerve was shown to be present in both spicules, and sensory elements were located in the genital cone. The increase in movements is believed to result from the removal of an inhibitor associated with the circumpharyngeal commissure. These results are discussed in terms of other observations on control mechanisms in nematodes and their functional morphology.

Functional significance of preserved color patterns of mollusks from the Gosport Sand (Eocene) of Alabama

1988 ◽  
Vol 62 (01) ◽  
pp. 83-87 ◽  
Author(s):  
Patricia H. Kelley ◽  
Charles T. Swann
Keyword(s):  
Functional Morphology ◽  
Functional Significance ◽  
Intraspecific Variability ◽  
Color Pattern ◽  
Color Patterns ◽  
Historical Factors ◽  
Life Mode ◽  
Molluscan Fauna ◽  
Excellent Preservation ◽  
Architectural Constraints

The excellent preservation of the molluscan fauna from the Gosport Sand (Eocene) at Little Stave Creek, Alabama, has made it possible to describe the preserved color patterns of 15 species. In this study the functional significance of these color patterns is tested in the context of the current adaptationist controversy. The pigment of the color pattern is thought to be a result of metabolic waste disposal. Therefore, the presence of the pigment is functional, although the patterns formed by the pigment may or may not have been adaptive. In this investigation the criteria proposed by Seilacher (1972) for testing the functionality of color patterns were applied to the Gosport fauna and the results compared with life mode as interpreted from knowledge of extant relatives and functional morphology. Using Seilacher's criteria of little ontogenetic and intraspecific variability, the color patterns appear to have been functional. However, the functional morphology studies indicate an infaunal life mode which would preclude functional color patterns. Particular color patterns are instead interpreted to be the result of historical factors, such as multiple adaptive peaks or random fixation of alleles, or of architectural constraints including possibly pleiotropy or allometry. The low variability of color patterns, which was noted within species and genera, suggests that color patterns may also serve a useful taxonomic purpose.

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