In contrast to these segmented or " merozoic " Cestodes, a few primitive forms have preserved a unisegmental' character and form the Monozoa or Cestodaria.
They resemble those of the sprat and pilchard in having a segmented yolk and there is no oil globule.
The endopodite may be retained as a small segmented palp at the side of the gnathobase or disappear (mandible of Crustacea, Chilopoda and Hexapods).
In the Thallophytes the cytoplasm may be segmented by constriction, due to the in-growth of a new cell wall from the old one, as in Spirogyra and Cladophora, or by the formation of cleavage furrows in which the new cell-wall is secreted, as occurs in the formation of the spores in many Algae and Fungi.
The female is a segmented, wormlike creature, spending her whole life within the body of the bee, wasp or bug on which she is parasitic. One end of her body protrudes from between two of the abdominal segments of the host; it has been a subject of dispute whether this protruded end is the head or the tail, but there can be little doubt that it is the latter.
Linnaeus in his Systema naturae (1735) grouped under the class Insecta all segmented animals with firm exoskeleton and jointed limbs - that is to say, the insects, centipedes, millipedes, crustaceans, spiders, scorpions and their allies.
They never bear segmented limbs (palps) and only exceptionally (as in the chafers) is the skeleton composed of more than one sclerite.
Carriere's researches (1897) on the make its appearance simultaneously throughout the whole length of embryology of the mason bee (Chalicodoma) agree entirely with the the plate; the anterior parts are segmented before the posterior.
- The nervous system is ectodermal in origin, and is developed and segmented to a large extent in connexion with the outer part of the body, so that it affords important evidence as to the segmentation thereof.
- Morphology of an Insect: the embryo of Gryllotalpa, somewhat diagrammatic. The longitudinal segmented band along the middle line represents the early segmentation of the nervous system and the subsequent median field of each sternite; the lateral transverse unshaded bands are the lateral fields of each segment; the shaded areas indicate the more internally placed mesoderm layer.
Opisthosoma when segmented showing the same number of somites as in the Pedipalpi; usually unsegmented, the prae-genital somite constricted to form the waist; the appendages of its 3rd and 4th somites retained as spinning mammillae.
- Opisthosoma dis tinctly segmented, furnished with tergal plates, as in the Ambly pygi; the ventral surface of the 1st and 2nd somites with large sternal plates, covering the genital aperture and the two pairs of FIG.
E, Lateral view of the whole body and two 1st appendages, showing the fusion of the dorsal elements of the prosoma into a single plate, and of those of the opisthosoma into an imperfectly segmented plate continuous with that of the prosoma.
The nervous system is, however, not segmented, and the excretory system is continuous throughout the worm.
We therefore regard the body of a Cestode as a single organism within which the gonads have become segmented, and the segmentation of the body as a secondary phenomenon associated with diffuse osmotic feeding in the narrow intestinal canal.
Schistocephalus becomes fully segmented in Gasterosteus and mature in aquatic birds (ducks, &c.).
Triaenophorus, indistinctly segmented, occurs in the pike.
By a series of changes similar to those by which the primary larva arose from a segmented egg, so do these secondary larvae or "rediae" arise from the germ-cells or germ-balls within the sporocyst.
The nervous system consists of a ganglion or brain, which lies dorsally about the level of the junction of the pharynx and the stomach, a nerve ring and a segmented neutral cord.
This division resembles the Cynipoidea in the position of the ovipositor, and in the two segmented trochanters.
The Aradidae have two segmented feet, and a large visible scutellum.
Annelids are segmented worms, and differ from the Arthropoda, which they closely resemble in many respects, by the possession of a portion of the coelom traversed by the alimentary canal.
The Copepoda have normally a segmented body, not enclosed in a bivalved shell-covering, the segments not exceeding eleven, the limbs not branchial.
- The body, seldom in any way segmented,, is wholly encased in a bivalved shell, the caudal part strongly inflexed, and almost always ending in a furca.
(e) Cytherellidae, which, unlike the Ostracoda in general, have the hinder part of the body segmented, at least ten segments being distinguishable in the female.
The next, the copepodid or cyclopid, stage is characterized by a cylindrical segmented body, with foreand hind-body distinct, and by having at most six cephalic limbs and two pairs of swimming feet.
The males of the Sericostomatidae have two or three segmented palps; their larvae inhabit running water and make cases of grains of sand, or of small stones.
This fact gives rise to the question whether the Mollusca are to be regarded as primitively segmented animals or not.
In animals which exhibit typical segmentation or metamerism, such as segmented worms (Chaetopoda), each segment or metamere possesses its own coelomic cavity, a pair of coelomic ducts, and a pair of nephridia.
All insects have the same regional division of the body into head, thorax and abdomen, the same number of legs, a pair of antennae and a segmented abdomen.
The cellular process from the axis which develops into a leaf is simple and undivided; it rarely remains so, but in progress of growth becomes segmented in various ways, either longitudinally or laterally, or in both ways.
This notochord represents the persistent primordial skeletal axis which, in the higher Craniata (though not so in the lower), gives way by substitution to the segmented vertebral column.
In the Entomobryidae the body is elongate and clearly segmented, but the dorsal region (tergum) of the prothorax is much reduced and the head downwardly directed; the spring is well developed.
r, a rodlet segmented in four, each segment containing one ripe spore.
In a Phyllopod such as Apus the limbs of the trunk consist of a flattened, unsegmented or obscurely segmented axis or corm having a series of lobes or processes known as endites and exites on its inner and outer margins respectively.
In the region of the trunk, in many cases, paired mesoblastic bands are formed, growing in length by the division of teloblastic cells at the posterior end, and becoming segmented into somites.
One large cell, or megamere, remains for some time unsegmented but is finally segmented and forms the endoderm cells which are invaginated.
The mesoderm becomes segmented, and the parapodia subsequently develop from before backwards; but almost all internal traces of segmentation are lost in the adult.
(4) Three of the rami of the primitive limb (endites 5 and 6, and exite I) specially developed as endopodite, exopodite, and epipodite - the first two often as firm and strongly chitinized, segmented, leg-like structures; the original axis or corm reduced to a basal piece, with or without a distinct gnathobase (endite i)- typical tri-ramose limb of higher Crustacea.
The Annelidan affinities are superficially indicated in so marked a manner by the thinness of the cuticle, the dermomuscular body-wall, the hollow appendages, that, as already stated, many of the earlier zoologists who examined Peripatus placed it among the segmented worms; and the discovery that there is some solid morphological basis for this determination constitutes one of the most interesting points of the recent work on the genus.
The body is indistinctly segmented, and is enveloped in a fold of the integument, usually with calcareous plates.
The small sinuous segmented body is enclosed, except for one small opening, in an enormous sac-like carapace, between the lamellae of which are protruded from the body the ovary and " liver," both large, bifurcate and ramified.
To the extreme development of the carapace in Laura, as compared with the segmented body, it would be difficult to find among crustaceans any analogy more striking than that of the great ovarial expansions in Nicothoe astaci, the little copepod parasite of the common lobster.
Some of the tin beads are shaped like segmented faience beads.
At intake testing, they often segmented consonant blends as " one sound.
The method used was segmented bloodworm on floating line.
These type of chambered Bronze Age cist burials are known as segmented cists.
To ensure fast access over slow connections, large documents have been segmented into " chunks " .
mouldhas an extended molded arch around the opening with a segmented keystone with blue mottled detail.
The guests at the single solution events are highly segmented group of people in a growing consumer segment.
Experience also indicates that major programs also tend to be segmented into major subcontracts (or teaming relationships ).
This image can be successfully segmented using a single threshold T1.
triangulated surface can be any shape or size allowing the re-application of a segmented surface to a new dataset.
Appendages of 1st pair large, three segmented and completely chelate; of 2nd pair either simple and pediform, or prehensile and subchelate; of remaining four pairs, similar in form, ambulatory in function; the basal segment of the 2nd, 3rd and sometimes of the 4th pairs of appendages furnished with sterno-coxal (maxillary) lobe.
- Degenerate atracheate gall-mites in which the body is produced posteriorly and annulated, as in Demodex, but in which the appendages of the 3rd and 4th pairs are long and normally segmented and those of the 5th and 6th pairs entirely absent.
TAPEWORMS. The Cestodes or Tapeworms form a class of purely endoparasitic Platyelmia, characterized by their elongate shape, segmented bodies, and the absence of a digestive system.
The Monozoa are unsegmented; the Ligulidce have segmented gonads and gonopores without any trace of somatic metamerization except secondary excretory pores in addition to the usual terminal one; the remaining Cestodes are unisegmental only in their larval stage, and all of them show in their later stages repetition of the reproductive organs and of the musculature.
They possess a modified anterior end, frequently with special sense organs, forming a head, a segmented nervous system, consisting of a pair of anterior, dorsally-placed ganglia, a ring surrounding the A ? ??Ã‚° D B L/ alimentary canal, and a double ventral ganglionated chain, a definite vascular system, an excretory system consisting of nephridia, and paired generative organs formed from the coelomic epithelium.
This class has been named the Prototracheata or Onychophora (see Arthropoda), and may be most appropriately placed in the system in the neighbourhood of the Myriapoda, though it must not be forgotten that it differs from the Myriapoda more than the Myriapoda differ from other Arthropoda, and that in some respects it presents features which recall the segmented worms (Annelida).
The forms of batrachians with which we are acquainted show the vertebral column to have been evolved in the course of time from a notochordal condition with segmented centra similar to that of early bony ganoid fishes (e.g.
Experience also indicates that major programs also tend to be segmented into major subcontracts (or teaming relationships).
The initial triangulated surface can be any shape or size allowing the re-application of a segmented surface to a new dataset.
Tapeworms are long, flat, segmented worms that live in your cat's intestinal tract.
Types of bracelets range from large and flamboyant bangles that can be worn mixed and matched with others giving a dramatic image on the arm, to delicate chains or segmented bracelets that add a subtle glitter on the wrist.
Popular bracelet designs include bangles, which are formed as single pieces and are slipped on over the wrist, and segmented bracelets that are formed from several pieces which are connected.
For example, DeBebians sells a set of 14 carat gold rings that features a segmented band with a round diamond in the center of each segment.
Osprey backpacks are segmented by the specific activity you plan to do.
This breaks down to about 7 or 8 million men in the U.S. [Discussed the difficulties of marketing to such a large but segmented age group] There is a fine line in marketing my panties.
This fact gave rise in ancient times to the false idea that the tapeworm originated from the union of these segments; and in modern times it has led to the view that the tapeworm is not a segmented organism (the monozoic view), but is a colony composed of the scolex which arises from the embryo and of the proglottides, which are asexually produced buds that, upon or before attaining their full size and maturity, become separated, grow, and, in some cases, live freely for a time, just as the segments of a strobilating jelly-fish grow, separate and become sexual individuals (the polyzoic view).
The body is not metamerically segmented and is composed of a muscular tunic covered externally by a more or less modified cellular layer.
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