Evolutionary Waves: Patterns in the Origins of Animal Phyla.

1985 ◽  
Vol 33 (2) ◽  
pp. 153 ◽  
Author(s):  
WG Inglis
Keyword(s):  
Body Wall ◽  
Functional Anatomy ◽  
Distinct Group ◽  
Body Cavity ◽  
The Body ◽  
Animal Groups ◽  
Structural Modifications ◽  
Hydrostatic Skeleton ◽  
Animal Phyla ◽  
Common Ancestors

Concordant patterns of embryology, morphology and functional anatomy delimit grades of animal phyla, each of which contains a 'Major Phylum': PARACOELOMATA (nom.nov.) = acoelomates + pseudocoelomates, flexible hydrostatic skeleton, Nematoda; DEUTEROSTOMIA (including lophophorates) = enterocoelic coelom, rigid internal skeleton, Chordata; and PROTOSTOMIA with two subgrades, MONOMERIC P. = unsegmented, single coelom, molluscan blastular cross, partial rigid exoskeleton, Molluscs; and POLYMERIC P. = segmented, multiple coelom, annelid cross, rigid exoskeleton, Uniramia. Such groups are usually treated as arbitrary stages in mono- and limited-branch phylogenies, but recent studies show them to be real and significant because the only phylogenetic links are from each Paracoelomata and Protostomia Phylum to Turbellaria; and each Deuterostomia Phylum to Cnidaria-Ctenophora and/or enteropneust Hemichordata. Similar grades have often been explained by hypothetical common ancestors, which are unnecessary if the phyla arose during 'evolutionary waves'. These attribute the origin of each grade to the likelihood that its constituent phyla arose independently, about the same time, from the same ciliary powered ancestral stock which was preadapted to enabling a potential body cavity to be actualized while evolving a cylindrical, wholly muscle-powered, body with a hydrostatic skeleton. Because such a skeleton is functionally dependent upon other structural modifications, particularly of the body wall, it could appear only when these were also available. If the latter could be supplied in a number of ways, all opportunities would be exploited and a body cavity would appear several times. The morphology suggests that this did happen, so that a pseudocoelom and coelom evolved independently in each phylum where they occur. Because of evidence that Protostomia and Deuterostomia were never linked during evolution, the origin of the coeloms in the former are explained by the Gonocoelic Theory and in the latter by the Enterocoelic. This, with the recognition of the monomeric protostomes as a distinct group, establishes that segmentation arose at the same time as the coeloms, so that their origins are one problem and not two as usually thought. Finally, protistan data suggest that Turbellaria, and so Paracoelomata and Protostomia, arose from 'close mitosis' flagellates, as did Fungi; while Cnidaria, and so Deuterostomia, arose from 'open mitosis' flagellates. as did Plantae. Thus, the classic Animalia division into Protostomia and Deuterostomia may represent a Protista division such that the animal groups are closer to fungi and plants respectively than they are to each other.

The locomotion of the acanthor of Moniliformis dubius (Archiacanthocephala)

Parasitology ◽  
1971 ◽  
Vol 62 (1) ◽  
pp. 35-47 ◽  
Author(s):  
P. J. Whitfield
Keyword(s):  
Intermediate Host ◽  
Body Wall ◽  
The Body ◽  
Research Fellowship ◽  
Wall Movement ◽  
Hydrostatic Skeleton ◽  
Laboratory Facilities ◽  
Longitudinal Muscles ◽  
Shape Changes

The mature egg and the acanthor of Moniliformis dubius have been redescribed with special emphasis on the features relevant to the locomotion of this larval acanthocephalan. The movements of acanthors have been analysed by the use of frame by frame study of filmed records of motile acanthors. Acanthors appear to use the same mode of locomotion for hatching, locomotion within the gut of the intermediate host and penetration of the host's gut wall. Movement is produced by a set of spiralled, longitudinal muscles in the body wall of the hind body and two rostellar retractor muscles. This musculature acts both directly on the body wall and indirectly by hydraulic effects via the hydrostatic skeleton of pseudocoelomic fluid. The spiny evertable rostellum and the backward facing spines of the hind body are the means whereby shape changes of the acanthor interact with the immediate environment to produce effective progression.I should like to thank Professor D. Arthur for the provision of laboratory facilities, Dr D. W. T. Crompton for the initial gift of eggs of M. dubius and Mr R. D. Reed for invaluable assistance with microcinematographic technique. The work was carried out during the tenure of a Nuffield Foundation Research Fellowship.

scholarly journals Pulmonary Mechanics and the Work of Breathing in the Semi-Aquatic Turtle, Pseudemys Scripta

1986 ◽  
Vol 125 (1) ◽  
pp. 137-155 ◽  
Author(s):  
Timothy Z. Vitalis ◽  
William K. Milsom
Keyword(s):  
Body Wall ◽  
Striated Muscle ◽  
Work Of Breathing ◽  
Body Cavity ◽  
The Body ◽  
Mechanical Work ◽  
Pulmonary Mechanics ◽  
Pump Frequency ◽  
Elastic Forces ◽  
Pseudemys Scripta

Measurements of pulmonary mechanics on anaesthetized specimens of the aquatic turtle Pseudemys scripta (Schoepff) indicate that the static pulmonary mechanics of the total respiratory system are determined primarily by the mechanics of the body wall rather than those of the lungs. This is also true under the dynamic conditions of pump ventilation at low pump frequencies. As pump frequency increases, the work required to inflate the multicameral lungs of the turtle begins to contribute an increasing portion to the total mechanical work required to produce each breath as measured from pressure volume loops. The rise in the work performed on the lungs results from an increase in the non-elastic, flow-resistive forces which must be overcome during ventilation. The primary bronchus to each lung is the most likely site of flow resistance. There is also a small elastic component to the work required to ventilate the lungs associated with movement of the intrapulmonary septa and the striated muscle surrounding the lungs. The contribution of the work required to distend the body cavity as a percentage of the total mechanical work required to generate each breath remains relatively unchanged with increasing ventilation frequency, indicating that the majority of the forces to be overcome in the body wall are elastic in nature. For a constant rate of minute pump ventilation, as frequency increases, the work done per minute to overcome elastic forces decreases, while that done to overcome non-elastic forces begins to rise. These opposing trends produce an optimum combination of pump volume and frequency at which the rate of mechanical work is minimum.

scholarly journals I. The Croonian lecture. —“ Observations on the locomotor system of echinodermata

1881 ◽  
Vol 32 (212-215) ◽  
pp. 1-11 ◽  
Keyword(s):  
Short Distance ◽  
Body Wall ◽  
Body Cavity ◽  
The Body ◽  
Considerable Time ◽  
Tube System ◽  
Radial Canal ◽  
Locomotor System ◽  
Direct Pressure ◽  
Stone Canal

In Holothuria the polian vesicle opens freely into a wide circular canal a short distance from the termination of the stone canal. From this circular canal five lozenge-shaped sinuses project forwards, and from each of these two large oval sinuses run forward parallel with each other─the ten oval sinuses becoming continuous with the hollow stems of the tentacles. Injection of the polian vesicle shows that it forms one continuous tube system with the circular canal and its sinuses, oval sinuses and tentacles, ampullæ and pedicels. Unless the pressure is kept up for a considerable time there is no penetration of the injected fluid into the stone canal, and either the ring, the vesicle, or a sinus gives way before the fluid reaches the madreporic plate. Specimens injected with a gelatine mass show that each canal sinus opens into a cæcal tube, which runs forwards internal to the sinuses of the tentacles as far as a wide circum-oral space. This space communicates by well-defined apertures with that portion of the body cavity which lies between the sinuses and the œsophagus, and which is reached through the circular apertures between the sinuses of the circular canal. Each canal sinus has three other apertures in its walls. It opens by a small round aperture into a radial canal, and the two other apertures occur as minute slits, one at each side of the orifice of the radial canal leading into the adjacent tentacle sinuses. When the tentacle into which the sinus opens is protruded, there is no constriction between the sinus and the tentacle ; but when the ten­tacle is retracted, there is a well-marked constriction at the junction of the sinus with the tentacle. The eversion of the perisome and the protrusion of the tentacles are effected chiefly by the shortening of the polian vesicle and the constriction of the longitudinal muscular bands, which run from the inner surface of the body wall between each two adjacent tentacle-sinuses ; but the circular fibres of the body wall also assist in the process by contracting immediately behind the group of sinuses, so as to act on them by direct pressure, and also indirectly by forcing the body fluid against them.

The bionomics and parasitic development of Tripius sciarae (Bovien) (Sphaerulariidae: Aphelenchoidea), a nematode parasite of sciarid flies (Sciaridae: Diptera)

Parasitology ◽  
1965 ◽  
Vol 55 (3) ◽  
pp. 559-569 ◽  
Author(s):  
George O. Poinar
Keyword(s):  
Adult Female ◽  
Body Wall ◽  
Pupal Stage ◽  
Body Cavity ◽  
The Body ◽  
National Institutes Of Health ◽  
New Host ◽  
Experimental Station ◽  
Rothamsted Experimental Station ◽  
Fat Bodies

After penetrating through the body wall into the haemocoel of Bradysia paupera, the fertilized female of Tipius sciarae increased in size and slowly expelled the enlarging uterine cells through the vulva.Within 7 days of penetration, the females were mature and began laying eggs into the haemocoel of the host. The eggs hatched in 3 days and, within 2 weeks, the host–s body was swarming with juvenile nematodes. The juveniles moulted three times in the body cavity of the host and 4th-stage forms emerged through ruptures in the intestine or body wall (in larval hosts) or were deposited on the surface of the soil (by adult female flies). They then moulted to adult forms while remaining ensheathed in their last juvenile cuticle, mated, and the fertilized infective females were ready to enter a new host.Most parasitized fly larvae died before reaching the pupal stage but some emerged as adults, still carrying the nematodes within them. All parasitized adult flies were sterile. Infested larvae had smaller fat bodies and adult histoblasts than normal larvae and took twice as long to develop.Preliminary tests suggested that this nematode may be useful in controlling sciarid gnats in glasshouses.T. sciarae (Bovien) and T. gibbosus (Leuckart) were compared.This work was done at Rothamsted Experimental Station, Harpenden, Herts, England, while the author held a postdoctoral grant from the National Institutes of Health, Bethesda, Maryland. I thank Mr F. G. W. Jones for a place in the Nematology Department, Dr Audrey Shepherd for supplying the New Blue R stain, Dr J. B. Goodey for advice, and Dr K. Lindhardt, Denmark, for the loaning of the late Dr Bovien–s slides of T. sciarae.

Memoirs: The Genital Organs of Stylaria lacustris, with an account of thier Development

1924 ◽  
Vol s2-68 (269) ◽  
pp. 147-186
Author(s):  
H. R. MEHRA
Keyword(s):  
Body Wall ◽  
Vas Deferens ◽  
Ejaculatory Duct ◽  
Body Cavity ◽  
The Body ◽  
Yolk Mass ◽  
Sperm Duct ◽  
Prostate Cells ◽  
Stylaria Lacustris ◽  
Columnar Cells

1. The genital organs of Stylaria lacustris are described in detail. The vas deferens opens into the atrium on the anterior face near the opening of the ejaculatory duct and not at the top as described by all the previous authors. The prostate surrounds not only the atrium but also the vas deferens in segment 6. 2. The prostate secretion passes through the atrial epithelium, which consequently hypertrophies and disappears 3. The development of the genital organs proceeds with great rapidity when the sexual phase appears, which occurs only once a, year from the end of September to the beginning of December. There is no long intervening period between the development of the gonads, and other genital organs. 4. The order of development seems to be connected with the time or order of their functioning. 5. The gonads are peritoneal in origin. The sperm-sac and orisac are large portions of the body-cavity enclosed by the extension backwards of septa ⅚ and 6/7 respectively. The yolk-mass is formed by a process of metabolic change in the cytoplasm of some of the ova. 6. The sperm-duct is partly peritoneal in origin and partly an ectodermal invagination. The funnel and the vas deferens rudiments arise by a proliferation of the peritoneal cells on the anterior face of septum ⅚, which assumes the form of a deeply shining plate of columnar cells with prominent nuclei. This after the funnel rudiment becomes the sperm-cord and penetrates the septum in front of the ovary, reaching near the body-wall the atrial rudiment, which is soon formed as an ec todermal invagination. The prostate cells arise from the peritoneum near the rentral body-wal1 of the sixth segment in the neighbourhood of the atrial rudiment. 7. The rudimentary female funnel, which opens ont at the female opening, arises as, an outgrowth from the peritoneum at the base of septum 6/7. 8. The spermatheca srises as an invagination from the ectoderm. I agree with Bergh that the sperm, zthecae are to be considered as new structures, and not phylogenetically connected with the genital ducts as Gatenby supposes to be the case in Tubifex rivulorum. 9. A fern stages obtained showing the development of these organs in Nais e1inguis confirm the above observntions.

Functional bursting by the dracunculoid nematode Philonema oncorhynchi

Parasitology ◽  
1974 ◽  
Vol 69 (3) ◽  
pp. 417-427 ◽  
Author(s):  
J. W. Lewis ◽  
D. R. Jones ◽  
J. R. Adams
Keyword(s):  
Sodium Chloride ◽  
Hydrostatic Pressure ◽  
Sockeye Salmon ◽  
Body Wall ◽  
Body Cavity ◽  
The Body ◽  
Absolute Pressure ◽  
Unit Surface Area ◽  
Ionic Exchange ◽  
Rate Of Increase

Using biomedical techniques experimental determinations of the hydrostatic pressure in the pseudocoel of adult female Philonema oncorhynchi indicated that the rate of increase in pressure (dP/dT) and absolute pressure values (cm/H2O) shown by bursting worms in distilled water are correlated with the diameter of the nematode. At bursting pressures, wall tension in a wide size range of worms was virtually identical, indicating that the bursting process is independent of muscular contraction. That the generation of the hydrostatic pressure was an osmotic phenomenon was confirmed by measuring dP/dT in prelarvigerous and larvigerous female worms subjected to different concentrations of sodium chloride, ranging from 89 to 800 m-osmol/kg, and also to a variety of solutions of similar osmolarity (155–175 m-osmol/kg), e.g. magnesium sulphate, urea, potassium chloride, sodium chloride and sucrose. The overall rate of uptake was faster in the larger worms but, per unit surface area, small worms had an uptake rate three times that of the large individuals.The prediction that the body wall of female P. oncorhynchi is permeable to ions such as Na+ was confirmed using radiolabelled 22Na and by bringing about changes in the osmolarity of worms subjected, for 5 min periods, to hyperosmotic solutions of sodium chloride and sucrose. The survival of P. oncorhynchi in the body cavity of sockeye salmon, Oncorhynchus nerka, is dependent upon the permeable nature of the body wall of P. oncorhynchi allowing the worm to function as an ‘osmometer', because as the anadromous O. nerka enters fresh water, the osmolarity of its blood plasma is known to decrease by about 15%. At the time of spawning in Cultus Lake, British Columbia, the body fluids of both female P. oncorhynchi and O. nerka are isosmotic, indicating that the worms are able to equilibrate to the above changes and at the same time preventing premature bursting in the body cavity of its host. However, osmotic invasion of water must occur far quicker than ionic exchange since complete release of larvae does take place when female worms pass out into the redd along with the eggs of the fish and burst.

scholarly journals Amassin, an olfactomedin protein, mediates the massive intercellular adhesion of sea urchin coelomocytes

2003 ◽  
Vol 160 (4) ◽  
pp. 597-604 ◽  
Author(s):  
Brian J. Hillier ◽  
Victor D. Vacquier
Keyword(s):  
Body Wall ◽  
Defense Mechanism ◽  
Sea Urchins ◽  
Body Cavity ◽  
Intercellular Adhesion ◽  
The Body ◽  
Coelomic Fluid ◽  
Relative Molecular Mass ◽  
Common Architecture ◽  
Massive Cell

Sea urchins have a fluid-filled body cavity, the coelom, containing four types of immunocytes called coelomocytes. Within minutes after coelomic fluid is removed from the body cavity, a massive cell–cell adhesion of coelomocytes occurs. This event is referred to as clotting. Clotting is thought to be a defense mechanism against loss of coelomic fluid if the body wall is punctured, and it may also function in the cellular encapsulation of foreign material and microbes. Here we show that this intercoelomocyte adhesion is mediated by amassin, a coelomic plasma protein with a relative molecular mass (Mr) of 75 kD. Amassin forms large disulfide-bonded aggregates that adhere coelomocytes to each other. One half of the amassin protein comprises an olfactomedin (OLF) domain. Structural predictions show that amassin and other OLF domain-containing vertebrate proteins share a common architecture. This suggests that other proteins of the OLF family may function in intercellular adhesion. These findings are the first to demonstrate a function for a protein of the OLF family.

scholarly journals Patterning mechanisms in the body trunk and the appendages of Drosophila

Development ◽  
1999 ◽  
Vol 126 (13) ◽  
pp. 2823-2828 ◽  
Author(s):  
G. Morata ◽  
E. Sanchez-Herrero
Keyword(s):  
Pattern Formation ◽  
Body Wall ◽  
Hox Genes ◽  
The Body ◽  
Gene Products ◽  
Animal Groups ◽  
Signalling Molecules

During evolution, many animal groups have developed specialised outgrowths of the body wall, limbs or appendages. The type of appendage depends on the identity of the segment where they appear, indicating that the Hox genes contribute to appendage specification. Moreover, work carried out principally in Drosophila has identified the gene products and the mechanisms involved in pattern formation in the appendages. In this essay, we compare the morphogenetic processes in the appendages and the body wall; the function of the Hox genes and the response to the signalling molecules involved in local patterning. We speculate that, although the basic mechanisms are similar, there are significant differences in the manner the body trunk and appendages respond to them.

Skin-digging tanaids: the unusual parasitic behaviour of Exspina typica in Antarctic waters and worldwide deep basins

2011 ◽  
Vol 23 (4) ◽  
pp. 343-348 ◽  
Author(s):  
Maria Chiara Alvaro ◽  
Magdalena Błażewicz-Paszkowycz ◽  
Niki Davey ◽  
Stefano Schiaparelli
Keyword(s):  
Body Wall ◽  
Ross Sea ◽  
Body Cavity ◽  
The Body ◽  
Free Living ◽  
Common Life ◽  
Life Styles ◽  
Antarctic Waters ◽  
The Antarctic ◽  
First Time

AbstractThe order Tanaidacea includes over 1000 species which are mainly free-living or tube-dwelling detritivores. Exspina typica Lang, 1968 represents an exception to these common life styles, having being found in the intestine and body cavity of deep sea holothuroids. The 2008 New Zealand ‘IPY-CAML Cruise’ held in the Ross Sea collected several deepwater holothuroids that were observed to carry specimens of E. typica inside their coelomic cavity. A clear interpretation of this association was hence possible. Even if E. typica shows slight adaptations to a parasitic life style, the tanaids were found to actively ‘dig’ into the host's skin, grasping tissue with their claws and producing tunnels in the body wall. It is therefore possible to clearly define this association, which is here reported from the Antarctic for the first time, as parasitism.

Ultrastructure of the Body Wall, Body Cavity, Nephridia and Spermatozoa in Four Species of the Chrysopetalidae (Annelida, “Polychaeta”)

2002 ◽  
Vol 241 (1) ◽  
pp. 37-55 ◽  
Author(s):  
Alexander B. Tzetlin ◽  
Thomas Dahlgren ◽  
Günter Purschke
Keyword(s):  
Body Wall ◽  
Body Cavity ◽  
The Body
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