The Post-embryonic Development of Phaenoserphus viator Hal. (Proctotrypoidea), a Parasite of the Larva of Pterostichus niger (Carabidae), with Notes on the Anatomy of the Larva

Parasitology ◽  
1929 ◽  
Vol 21 (1-2) ◽  
pp. 1-21 ◽  
Author(s):  
L. E. S. Eastham

1. The life-history of Phaenoserphus viator is described.Four larval instars are found, endoparasitic in the larvae of Pterostichus niger. At thee nd of the last larval instar the parasites, which may number as many as 45 in a single host, emerge, and while still attached, pupate without spinning a cocoon.Adults may appear in August or September.The effect of the parasite in inhibiting metamorphosis of the host is discussed.2. The first observed larva is atracheate and incompletely segmented at first and is of the polypod type bearing paired prolegs on the body segments.Subsequent instars are apodate.The tracheal system develops progressively in the several instars, but only becomes functional in the final stage.3. The anatomy of the larva is briefly described with the exception of the musculature.Tracheal development is described. Gas only appears in the tracheae after the development of the tracheole cells puts the tracheae into communication with the body wall and other organs.In the circulatory system an important accessory organ is the neural sinus, formed by the enclosure of the ventral nerve cord beneath a connective tissue curtain.The imaginal discs of the hypodermis are briefly described, these being clearly defined in the head, thorax, and posterior abdominal segments.The nervous system consists of a brain, suboesophageal ganglion and 11 ventral ganglia, the most posterior being tripartite. This system is connected with the sympathetic, by nerves passing from the cerebral commissures to a frontal ganglion which lies above the oesophagus and behind the labrum.

Parasitology ◽  
1931 ◽  
Vol 23 (3) ◽  
pp. 380-395 ◽  
Author(s):  
H. G. H. Kearns

1. Two species of endoparasites, a Chalcid Stenomalus micans and a Braconid Coelineus niger, were found in every sample of “gouted” barley examined from a number of counties in southern England.2. Chlorops infestations were severe in 1928 in many districts, and the majority of the “gouted” shoots were of winter-type damage, of which 68 percent. were parasitised, two-thirds by S. micans.3. The larval anatomy of S. micans is described:(a) There are five larval instars, each of which is described.(b) The first larval instar appears to be partly predaceous.(c) The larvae can be kept alive for 5 days on the surface of normal physiological saline solution and moulting occurs, which enables the instar to be determined with certainty.(d) The tracheal system is devoid of spiracles until the fourth larval instar; spiracles then develop and are connected to the former rudimentary stigmatic trunks prior to the death of the host.(e) The fourth instar larva develops a cephalic boring armature which is used for breaking up the internal organs of the host and also to bore an exit hole through the latter's body wall.4. The pupa of S. micans is described and sex differences are indicated.


1968 ◽  
Vol 46 (3) ◽  
pp. 321-327 ◽  
Author(s):  
M. A. Alikhan

Tbe circulatory system, lying in the mid-dorsal line of the body, consists of an oval heart, the opthalmic artery, and a dorsal abdominal artery.The digestive system comprises a wide, large alimentary tube and two pairs of digestive glands. An oesophagus, a proventriculus, midgut, and a short proctodacum or hindgut form the digestive tube. The digestive glands are very well developed and are beaded in form; each pair lies on either side of the alimentary canal.The reproductive organs are well developed in both sexes: in the male they consist of paired testes and their vas deferentia, and in the female paired bilobed ovaries and oviducts.A cerebral or supraoesophageal ganglion, a suboesophageal ganglion, and seven thoracic ganglia form the nervous system. The supraoesophageal ganglion is united with the suboesophageal ganglion by means of the circumoesophageal commissures, whereas the thoracic ganglia and suboesophageal ganglia are linked with each other by paired connectives.The gills and the tracheae are the organs of respiration. The gills are borne of the bases of the pleopods and are enclosed in the branchial chamber. The tracheae are located on the lateral lobes of the first two pleopods only.


ZooKeys ◽  
2019 ◽  
Vol 822 ◽  
pp. 1-15 ◽  
Author(s):  
Stephen D. Cairns ◽  
Michelle L. Taylor

A history of the description of the 50 valid species of Narella is given, beginning with the first species described in 1860. To help differentiate the various species, a tabular and a polychotomous key are provided. The species in the keys are arranged using nine characters or character sets that are believed to be of value at the species level. New characters or new significance given to previously described characters used in our keys include: 1) the nature of the dorsolateral edge of the basal scale, being ridged or not, 2) the thickness of the body wall scales, and 3) the arrangement of the coenenchymal scales (imbricate or mosaic), their thickness (thin or massive), and their outer surface ornamentation (ridged or not). All characters used in the keys are illustrated.


1972 ◽  
Vol 182 (1068) ◽  
pp. 331-350 ◽  

The external surface of the epitheca in modern and fossil corals is marked by tiny ridges lying parallel to the epithecal rim. These ridges have been assumed to be daily growth increments, and have been linked with supposed lunar and seasonal events recorded in the skeleton, to compute aspects of the history of the Earth’s rotation. This communication presents struc­tural and experimental evidence to show that the growth-ridges in the epithecae of modern hermatypic scleractinian corals, particularly Manicina areolata (Linnaeus), are formed as a result of daily changes in the shape of the tissues secreting the epithecae. The changes in shape of the tissues are an integral part of the mechanism by which the body wall of these corals is adjusted in position to accommodate for epithecal growth. This adjustment takes place in concert with a daily cycle of expansion and contraction of the animals. Because the epitheca is formed at the perimeter of the skeleton-secreting layer, its growth involves certain fundamental requirements. The presence of growth-ridges in all coral epi­thecae suggests that all corals meet, or met, these requirements with a similar mechanism to that which operates in the hermatypic species studied. However, the mechanism is not necessarily linked to a daily cycle of expansion and contraction.


1956 ◽  
Vol s3-97 (38) ◽  
pp. 235-249
Author(s):  
R. B. CLARK

The four longitudinal vessels of the circulatory system of Nephtys californiensis are dorsal, sub-intestinal, and neural, the latter being paired. There is a complete longitudinal circulation; the dorsal vessel communicates with the sub-intestinal by way of the proboscidial circulation and with the neural by way of the circum-oral vessels. In each middle and posterior segment segmental vessels from each of the longitudinal trunks carry blood to and from the parapodia and body-wall. The segmental circulation is completed by a circum-intestinal vessel connecting the dorsal and subintestinal vessels in each segment and an intersegmental branch connecting the dorsal and sub-intestinal segmental vessels. A trans-septal branch of the neural segmental vessel communicates with the sub-intestinal segmental vessel. This arrangement is modified in anterior segments which house the muscular, eversible pharynx, and no blood-vessels cross the coelom except by running through the body-wall. On anatomical grounds and by comparison with other polychaetes it seems likely that segmental is subordinate to longitudinal circulation. There are no endothelial capillaries such as have been described in some other polychaetes; instead there are numerous blindending vessels the walls of which are composed of the same three layers as other vessels and which are probably contractile. The dorsal vessel, where it is in contact with the ventral surface of the supra-oesophageal ganglion, forms a plexus in close association with a modified part of the brain capsule and a special axonal tract within the ganglion. It is thought that by way of this ‘cerebro-vascular complex’, hormones produced in the neurosecretory cells of the brain pass into the blood-stream.


Author(s):  
Chris Cooper

‘A history of blood’ considers why the colour red and blood hold such pre-eminence in human language and culture. Views about what function blood actually performed in the body have varied widely through history. The studies of 2nd-century physician Galen are described along with procedures such as bloodletting, used in medicine for a long time. The structure of the vessels that contain blood in the body—arteries and veins—has always intrigued scholars. The 13th-century Islamic physician Ibn al-Nafis was the first to propose a circulatory system, but it was in 1628, when William Harvey, physician to King James I, published his findings, that the true circulatory system was explained.


2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Igor Yu. Dolmatov

Aspects of asexual reproduction in holothurians are discussed. Holothurians are significant as fishery and aquaculture items and have high commercial value. The last review on holothurian asexual reproduction was published 18 years ago and included only 8 species. An analysis of the available literature shows that asexual reproduction has now been confirmed in 16 holothurian species. Five additional species are also most likely capable of fission. The recent discovery of new fissiparous holothurian species indicates that this reproduction mode is more widespread in Holothuroidea than previously believed. New data about the history of the discovery of asexual reproduction in holothurians, features of fission, and regeneration of anterior and posterior fragments are described here. Asexual reproduction is obviously controlled by the integrated systems of the organism, primarily the nervous system. Special molecular mechanisms appear to determine the location where fission occurs along the anterior-posterior axis of the body. Alteration of the connective tissue strength of the body wall may play an important role during fission of holothurians. The basic mechanism of fission is the interaction of matrix metalloproteinases, their inhibitors, and enzymes forming cross-link complexes between fibrils of collagen. The population dynamics of fissiparous holothurians are discussed.


2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Tomás Lombardo ◽  
Guillermo A. Blanco

Clot formation in the sipunculidThemiste petricola, a coelomate nonsegmented marine worm without a circulatory system, is a cellular response that creates a haemostatic mass upon activation with sea water. The mass with sealing properties is brought about by homotypic aggregation of granular leukocytes present in the coelomic fluid that undergo a rapid process of fusion and cell death forming a homogenous clot or mass. The clot structure appears to be stabilized by abundant F-actin that creates a fibrous scaffold retaining cell-derived components. Since preservation of fluid within the coelom is vital for the worm, clotting contributes to rapidly seal the body wall and entrap pathogens upon injury, creating a matrix where wound healing can take place in a second stage. During formation of the clot, microbes or small particles are entrapped. Phagocytosis of self and non-self particles shed from the clot occurs at the clot neighbourhood, demonstrating that clotting is the initial phase of a well-orchestrated dual haemostatic and immune cellular response.


A considerable amount of work has been done with regard to the water-balance of insects (recently summarized by Buxton, 1932), and on the physical laws governing the water loss from insects, but as yet no one has determined exactly from what part of the insect’s body water is lost. It has been found that when insects are not excreting at all, considerable amounts of water are evaporated from their bodies—quantities frequently sufficient to cause death from desiccation. There are three possible ways in which an insect might lose this water (apart from the alimentary canal) : (i) through the general surface of the body wall; (ii) through the spiracular system; and (iii) partly from the body surface and partly through the spiracular system. The fact that carbon dioxide passes readily through chitin (Dewitz, 1890), and that insects get rid of some of that gas through their integument (v. Buddenbrock and Rohr, 1922), suggests that watervapour may also pass from the insect's body in a similar manner. However, Hazelhoff (1927) states that resting insects keep their spiracles closed most of the time, only opening them sufficiently often to obtain enough oxygen, in order to conserve water. He believes that most of the water is lost through the tracheal system. The observations of Gunn (1933) on the cockroach and Mellanby (1932, b ) on the mealworm also suggest that a high proportion of the water evaporated from those insects is lost through the spiracles. The experiments described in this paper show how spiracular opening affects the rate at which insects lose water by evaporation, and the results obtained make it possible to say from what parts of the body this loss takes place.


Fossil Record ◽  
2020 ◽  
Vol 23 (2) ◽  
pp. 141-149
Author(s):  
Marine Fau ◽  
Loïc Villier ◽  
Timothy A. M. Ewin ◽  
Andrew S. Gale

Abstract. Forcipulatacea is one of the three major groups of extant sea stars (Asteroidea: Echinodermata), composed of 400 extant species, but only known from fewer than 25 fossil species. Despite unequivocal members being recognized in the early Jurassic, the evolutionary history of this group is still the subject of debate. Thus, the identification of any new fossil representatives is significant. We here reappraise Ophidiaster davidsoni de Loriol and Pellat 1874 from the Tithonian of Boulogne, France, which was assigned to another major extant group, the Valvatacea, and reassign it within a new forcipulatacean genus, Psammaster gen. nov. Psammaster davidsoni gen. nov. possess key Forcipulatacea synapomorphies including compressed ambulacrals and adambulacrals and typical organization of the body wall and arm ossicles. A phylogenetic analysis including Psammaster davidsoni gen. nov. does not place it within any existing forcipulatacean family. Instead, Psammaster davidsoni gen. nov. exhibits a mix of plesiomorphic and derived characters and is resolved as a sister clade to a large group including the Asteriidae, Stichasteridae, and Heliasteridae. Removal of this species from the Ophidiasteridae means their oldest fossil representative now dates from the Santonian, Upper Cretaceous.


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