Cnidaria

1989 ◽  
Author(s):  
Heinz A. Lowenstam ◽  
Stephen Weiner
Keyword(s):  
Calcium Sulfate ◽  
Body Wall ◽  
Structural Features ◽  
The Body ◽  
Internal Space ◽  
Gravity Perception ◽  
Sessile Polyp ◽  
Gastrovascular Cavity ◽  
Mode Of Life ◽  
Pass Through

The phylum Cnidaria or Coelenterates includes sea anemones, jellyfish, hydras, sea fans, and, of course, the corals. With few exceptions they are all marine organisms and most are inhabitants of shallow water. In spite of the great variation in shape, size, and mode of life, they all possess the same basic metazoan structural features: an internal space for digestion (gastrovascular cavity or coelenteran), a mouth, and a circle of tentacles, which are really just an extension of the body wall. The body wall in turn is composed of three layers: an outer layer of epidermis, an inner layer of cells lining the gastrovascular cavity, and, sandwiched between them, a so-called mesoglea (Barnes 1980). All these features are present in both of the basic structural types: the sessile polyp and the free-swiming medusa. During their life cycle, some cnidarians exhibit one or the other structural type whereas others pass through both. Most Cnidaria have no mineralized deposits. The ones that, to date, are known to have mineralized deposits are listed in Table 5.1. They are found in both the free-swimming medusae and the sessile polyps. Not surprisingly, these have very different types of mineralized deposits. In the medusae they are located exclusively within the statocyst where they constitute an important part of the organism’s gravity perception apparatus. Interestingly the statoconia of the Hydrozoa, examined to date for their major elemental compositions only, are all composed of amorphous Mg-Ca-phosphate, whereas those of the Scyphozoa and Cubozoa are composed of calcium sulfate. Calcium sulfate minerals (presumably gypsum) are not commonly formed by organisms and the only other known occurrence is in the Gamophyta among the Protoctista. Spangenberg (1976) and her colleagues have expertly documented this phenomenon in the Cnidaria. (For a more detailed discussion of mineralization and gravity perception see Chapter 11.) The predominant mineralized hard part associated with the sessile polyps is skeletal. These can take the form of skeletons composed of individual spicules, spicule aggregates, or massive skeletons. They are composed of aragonite, calcite, or both.

On certain Semi-carnivorous Anthomyid Larvae

Parasitology ◽  
1930 ◽  
Vol 22 (2) ◽  
pp. 168-181 ◽  
Author(s):  
D. Keilin ◽  
P. Tate
Keyword(s):  
Alimentary Canal ◽  
Body Wall ◽  
Anatomical Structure ◽  
The Body ◽  
Sensory Organs ◽  
Ventral Region ◽  
Anatomical Features ◽  
Mode Of Life ◽  
Ventral Wall

In previous papers one of us (Keilin, 1915, 1917) has shown that among cyclorrhaphous dipterous larvae there is a remarkable correlation between the anatomical structure of the larvae and their mode of life. Although the mode of life of the larvae is in correlation with such anatomical features as thickness and hardness of the body-wall, the development of sensory organs on the head, and the structure of the alimentary canal, it is in the bucco-pharyngeal armature that the most obvious and important adaptations are to be found. The most important of these adaptations may be mentioned briefly. In certain cyclorrhaphous dipterous larvae the ventral wall of the basal sclerite of the bucco-pharyngeal armature has a number of longitudinal ridges projecting into the lumen of the pharynx. These ridges are usually Y-shaped at their free borders, and form a series of longitudinal channels in the ventral region of the pharynx. In other cyclorrhaphous dipterous larvae such ridges are absent and the ventral wall of the pharynx is smooth. This character allows the larvae to be divided into two groups—“all cyclorrhaphous dipterous larvae parasitic on the most diverse animals or on plants, as well as carnivorous larvae, and larvae which suck the blood of mammals, never have ridges in their pharynx; on the contrary, ridges are always present in saprophagous larvae” (Keilin, 1915). All the larvae which are devoid of ridges and are either parasitic, carnivorous, pass their whole life in the uterus of the female, or are phytophagous, may be united into the group of biontophagous; all larvae which have ridges are saprophagous.

Biology, morphology and anatomy of aphidophagous syrphid larvae

Parasitology ◽  
1939 ◽  
Vol 31 (1) ◽  
pp. 78-120 ◽  
Author(s):  
Madan Lal Bhatia
Keyword(s):  
Comparative Morphology ◽  
The Body ◽  
Individual Species ◽  
Larval Stages ◽  
The Third ◽  
Third Stage ◽  
Mode Of Life ◽  
Pass Through ◽  
The Individual ◽  
Syrphid Larvae

The paper deals with the biology, morphology and anatomy of seven species of syrphid larvae viz. Syrphus luniger Meig., S. balteatus De Greer, S. ribesii Linne, Catabomba pyrastri Linne, Sphaerophoria flavicauda Zett., Sph. scripta Linne, and Platychirus scutatus Meig.The habitat, mode of progression, aphidophagous habits and characteristic coloration are described for each species.It is shown that the larvae of all the above species, like larvae of other cyclorrhaphous Diptera, definitely pass through three stages separated by two moults. The mode of dehiscence of the puparium is described briefly.Each of the species, except Catabomba pyrastri, has three generations in the breeding season which lasts from May to October. Platychirus scutatus hibernates only in the larval stage, but the other species may be found in both the larval and pupal stages during the winter.The larvae of all the above species, except Syrphus balteatus, are commonly parasitized by ichneumonid larvae.The morphology of the egg, the three larval stages and the puparium of S. luniger is described in detail.The characters common to the third stage larvae of all the species dealt with are summarized and short descriptions of the third stage larvae and puparia of the individual species are given. The general appearance of the living larvae and details of the buccopharyngeal armature, spiracles and puparia of each of the species is represented in figures.In connexion with the pupae a number of new structures are described and it is suggested that some of them are concerned with the formation of the characteristic shape of the puparium and with the dehiscence of the puparium.Internal pupal spiracles are present in all the species dealt with, but external pupal spiracles are present only in Platychirus scutatus.The anatomy of P. scutatus is described and figured, an account being given of all the structures except the musculature of the body wall. Study of the anatomy affords evidence as to the carnivorous mode of life of the larvae and also indicates that the larvae have evolved from aquatic forms.The comparative morphology of the Syrphinae is discussed with respect to the relationship of the Syrphinae to other Aschiza and to the cyclorrhaphous Diptera.

Memoirs: On the Structure and Functions of the Cerata or Dorsal Papillæ in some Nudibranchiate Mollusca

1890 ◽  
Vol s2-31 (121) ◽  
pp. 41-64
Author(s):  
W. A. HERDMAN
Keyword(s):  
Respiratory Function ◽  
Body Wall ◽  
The Body ◽  
The Other ◽  
Mode Of Life ◽  
Extended Surfaces ◽  
The One ◽  
Further Development ◽  
Structure And Functions

1. In Doris there are true branchiæ and no cerata. In Ancula both branchiæ and cerata are present. In Tritonia and Dendronotus there are cerata, but no true branchiæ. In Ancula, Tritonia, and Dendronotus the cerata, whether simple or branched, large or small, are merely processes of the body-wall (parieto-cerata) and contain no special organs or structures. 2. In Doto and Eolis there are no true branchiæ. The cerata (hepato-cerata) are large, and contain extensive hepatic diverticula. 3. In Eolis the hepato-cerata contain also cnidophorous sacs which communicate on the one hand with the distal end of the hepatic caecum, and on the other with the exterior at the apex of the ceras. 4. Morphologically, all the forms of cerata are probably epipodial processes. 5. The large, elaborately branched parieto-cerata of Dendronotus are merely a further development of the small tufted parieto-cerata of Tritonia, and although they may on account of their extended surfaces have secondarily acquired to a certain extent a respiratory function, they cannot be regarded as specialised branchiæ. 6. The cerata, whether they are large branched parieto-cerata as in Dendronotus, or hepato-cerata containing the greater part of the liver as in Doto, or having cnidophorous sacs in addition as in Eolis, are not of primary importance either in respiration or in digestion, but give to the animals, by their varied shapes and colours, appearances which are in some cases protective and mimetic, and in others conspicuous and warning, as may be found best suited to their individual surroundings and mode of life.

Mechanical Diversity of Connective Tissue of the Body Wall of Sea Anemones

1977 ◽  
Vol 69 (1) ◽  
pp. 107-125
Author(s):  
M.A. R. KOEHL
Keyword(s):  
Connective Tissue ◽  
Body Wall ◽  
Polarized Light ◽  
Structural Features ◽  
Mechanical Tests ◽  
The Body ◽  
Sea Anemones ◽  
Collagen Fibres ◽  
Postural Changes ◽  
Anthopleura Xanthogrammica

Techniques for analysing polymer mechanics were used to describe quantitatively the time-dependent mechanical properties of the body-wall connective tissue (mesogloea) and to indicate macromolecular mechanisms responsible for the mechanical behaviour of two species of sea anemones, Metridium senile and Anthopleura xanthogrammica. 1. The mesogloea of M. senile is more extensible and less resilient than that of A. xanthogrammica when stressed for periods comparable to the duration of flow forces the anemones encounter and the postural changes they perform.2. Polarized light microscopy and SEM reveal that the reinforcing collagen fibres in the mesogloea are aligned parallel with the major stress axes in the body wall.3. Mechanical tests and observations of composition and microstructure indicate that the mesogloea of A. xanthogrammica is less extensible than that of M. senile because molecular entanglements (due to more closely packed parallel collagen fibres and to a higher concentration of polymers in the interfibrillar matrix) retard the extension of A. xanthogrammica mesogloea. This study illustrates how structural features on the macromolecular and microscopic levels of organization of an organism can equip that organism for the particular mechanical activities it performs and the environmental forces it encounters.

The Role of Oesophageal Rhythms in the Behaviour of Arenicola Ecaudata Johnston

1951 ◽  
Vol 28 (1) ◽  
pp. 51-56
Author(s):  
G. P. WELLS ◽  
ELINOR B. ALBRECHT
Keyword(s):  
Body Wall ◽  
The Body ◽  
Rhythmic Contraction ◽  
Back Ground ◽  
Continuous Background ◽  
Mode Of Life ◽  
Nearly Continuous

1. Arenicola ecaudata differs not only in structure, but in mode of life, from A. marina. Our results indicate that there are also great differences in behaviour physiology. 2. The brainless isolated extrovert of ecaudata traces a continuous, or nearly continuous, background of activity, upon which prominent spells of vigorous rhythmic contraction appear at intervals of the order of 30-40 min. Similar spells are sometimes shown by the corresponding preparation from marina, whose characteristic f cycle can be regarded as produced by the organization of the back-ground activity of ecaudata into vigorous and regularly spaced outbursts. 3. There is little evidence of a pacemaker role of the oesophagus in ecaudata. If the movements of the extrovert and body wall are simultaneously recorded, they generally exhibit correlated outbursts of variable and fluctuating pattern, and very unlike the behaviour of the brainless extrovert. Similar outbursts are shown by the body wall after severance of its connexion with the extrovert. They are probably of central nervous origin.

Lymphangiomatosis of the Body Wall: A Report of Two Cases Associated with Chylothorax and Fatal Outcome

1997 ◽  
Vol 17 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Philippe Moerman ◽  
Chris Van Geet ◽  
Hugo Devlieger
Keyword(s):  
Body Wall ◽  
Fatal Outcome ◽  
The Body

scholarly journals A screen for genetic loci required for body-wall muscle development during embryogenesis in Caenorhabditis elegans.

Genetics ◽  
1994 ◽  
Vol 137 (2) ◽  
pp. 483-498
Author(s):  
J Ahnn ◽  
A Fire
Keyword(s):  
Caenorhabditis Elegans ◽  
Myosin Heavy Chain ◽  
Muscle Cell ◽  
Heavy Chain ◽  
Body Wall ◽  
Muscle Development ◽  
Contractile Function ◽  
The Body ◽  
Body Wall Muscle ◽  
Genetic Loci

Abstract We have used available chromosomal deficiencies to screen for genetic loci whose zygotic expression is required for formation of body-wall muscle cells during embryogenesis in Caenorhabditis elegans. To test for muscle cell differentiation we have assayed for both contractile function and the expression of muscle-specific structural proteins. Monoclonal antibodies directed against two myosin heavy chain isoforms, the products of the unc-54 and myo-3 genes, were used to detect body-wall muscle differentiation. We have screened 77 deficiencies, covering approximately 72% of the genome. Deficiency homozygotes in most cases stain with antibodies to the body-wall muscle myosins and in many cases muscle contractile function is observed. We have identified two regions showing distinct defects in myosin heavy chain gene expression. Embryos homozygous for deficiencies removing the left tip of chromosome V fail to accumulate the myo-3 and unc-54 products, but express antigens characteristic of hypodermal, pharyngeal and neural development. Embryos lacking a large region on chromosome III accumulate the unc-54 product but not the myo-3 product. We conclude that there exist only a small number of loci whose zygotic expression is uniquely required for adoption of a muscle cell fate.

scholarly journals Cloning and sequencing of cDNA of Sarcophaga peregrina humoral lectin induced on injury of the body wall.

1985 ◽  
Vol 260 (22) ◽  
pp. 12228-12233 ◽  
Author(s):  
H Takahashi ◽  
H Komano ◽  
N Kawaguchi ◽  
N Kitamura ◽  
S Nakanishi ◽  
...  
Keyword(s):  
Body Wall ◽  
The Body ◽  
Cloning And Sequencing

scholarly journals Mutations Affecting Nerve Attachment of Caenorhabditis elegans

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1611-1622 ◽  
Author(s):  
Go Shioi ◽  
Michinari Shoji ◽  
Masashi Nakamura ◽  
Takeshi Ishihara ◽  
Isao Katsura ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Body Wall ◽  
The Body ◽  
Genetic Loci ◽  
Muscle Attachment ◽  
C Elegans ◽  
Ventral Cord ◽  
Excretory Canal

Abstract Using a pan-neuronal GFP marker, a morphological screen was performed to detect Caenorhabditis elegans larval lethal mutants with severely disorganized major nerve cords. We recovered and characterized 21 mutants that displayed displacement or detachment of the ventral nerve cord from the body wall (Ven: ventral cord abnormal). Six mutations defined three novel genetic loci: ven-1, ven-2, and ven-3. Fifteen mutations proved to be alleles of previously identified muscle attachment/positioning genes, mup-4, mua-1, mua-5, and mua-6. All the mutants also displayed muscle attachment/positioning defects characteristic of mua/mup mutants. The pan-neuronal GFP marker also revealed that mutants of other mua/mup loci, such as mup-1, mup-2, and mua-2, exhibited the Ven defect. The hypodermis, the excretory canal, and the gonad were morphologically abnormal in some of the mutants. The pleiotropic nature of the defects indicates that ven and mua/mup genes are required generally for the maintenance of attachment of tissues to the body wall in C. elegans.

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