Posterior Sucker Research Articles

Observations on lesser-known flatworms: Udonella

Udonella caligorum is acknowledged as a monogenean by some (Baer & Euzet, 1961; Yamaguti, 1963), but not by others (Ivanov, 1952; Bychowsky, 1957). It also has many similarities to Temnocephala, a rhabdocoel turbellarian. Light and electron microscope studies showed that the posterior sucker is glandular and that neither the adult nor eggs possess hooks; the head-gland secretion is eosinophilic and granular, and the tegument composed primarily of secretory granules and mitochondria. Ten pair of cells appearing to be paranephrocytes are present. Udonella larvae were shown to be larger than the host copepod nauplii, so transmission of worms between hosts must occur either during host mating, casual contact of hosts, or through free worms on the surface of the fish which the copepod infests.

Megalodiscus temperatus: Scanning electron microscopy of the tegumental surfaces

The tegumental surface of Megalodiscus temperatus forms cobblestonelike areas with rows of indentations encircling the worm. This pattern merges in several areas into folds and ridges, some of which represent the musculature of the posterior sucker and genital pore. Papillae surrounding the base of the oral sucker appear as two types: one with a bulb-like base and a short apical knob; the second typified by a hair-like structure (cilium?) of variable length projecting from a pit. From their location on the oral sucker and the resemblance to previously described structures, they are presumed to be sensory receptors. A circle of papillae on the closed posterior sucker was also observed. Rod-shaped bacteria were seen adhering to some of the worms observed but they were not found to be in any special association with the tegument or in any specific areas of the worm's surface.

Scanning and transmission electron microscope studies on the sensory sucker papillae of the fish parasite Entobdella soleae (Monogenea).

The ventral surface of the posterior sucker of Entobdella soleae, a monogenean skin parasite of the sole Solea solea, is covered with more than 800 papillae ranging in size from 2.5–19 μm in diameter. The papillae are penetrated by nerves which double over themselves to form a stack-like array of lamellae running parallel to the surface of the haptor. No cilia or associated structures are present within these presumed sense organs and the papillae have no opening to the exterior. The much larger sucker papillae of a related species, E. hippoglossi, have been shown to have a similar ultrastructure. The possibility that the papillae may be contact receptors or strain receptors, providing proprioceptive information assisting the coordination of the attachment organ, is discussed and the papillae are compared with vertebrate touch receptors.

The segmentation of the gnathobdellid leeches with special reference to the Indian leech Hirudinaria and medicinal leech Hirudo.

AbstractLarge number of annuli in Hirudinea are not true segments, and in the absence of spacious bodycavity and septa in adult no decision was taken regarding limit of a somite, until Gratiolet 1862 recognised a segment by colour marking, repetition of nephridial openings, and especially by the presence of segmental receptors, distinguishing first annulus of a segment. Whitman 1884 gave precision to these determinations and analyzed morphology of leeches to logical completeness. He recognised that though Hirudinaria and Hirudo have 102 body annuli and posterior sucker, true segments are only 26 plus 7.Castle ('00) and Moore ('00) proposed a new scheme of segmentation, with segmental receptor bearing annulus, as central annulus of a complete somite, with nerve ganglion, like that of other annelids, in center of a segment. They orientated everything roundabout the ganglion without noticing distorted fate of organ system.In this paper both the views are compared. Morphological and embryological studies reveal that the annulus bearing the segmental receptors in uniformly first annulus of all segments, including incomplete segments at the two extremities, with nerve ganglion in first annulus of the segment.Clitellum occupies three natural segments, IX, X, XI; crop caeca, nephridia, testis sacs, haemocoelomic channels and “rhomboidal figures” formed by ventrolaterals, all make a complete unit, well integrated in such segment. Conclusive evidence comes from the presence of septa at the level of each nerve ganglion in embryos of Hirudinaria. These observations corroborate Gratiolet and Whitman's view.

Esterase activity in certain glands of leeches (Annelida: Hirudinea)

1. 1. Out of eight species of leech examined, only one, Piscicola geometra, was found to possess histochemically demonstrable esterase activity in significant amounts. Activity is great in the salivary glands and glands of the posterior sucker. This activity facilitated the recognition of salivary glands in the post-clitellar region. 2. 2. The use of modifiers suggested that the activity in the salivary glands is mainly caused by a B-esterase, and in the sucker, by cholinesterases. 3. 3. The function of the enzyme in each region is discussed. There is evidence that the salivary secretion is injected into the host during feeding so that the possibility of correlating the presence of esterases with hirudin was considered, as well as the suggestion that salivary secretion could act digestively, either extra-corporeally on the tissues of the host, or on the ingested blood contained within the crop of the leech.

SOME ASPECTS OF THE BIOLOGY OF THE MARINE LEECHHEMIBDELLA SOLEAE

The biology of the marine leechHemibdella soleaewas studied. It was found that multiple infections were common, the leeches being attached by the posterior sucker to spines on the ctenoid scales of the upper surface of the sole. It was observed that in aqqaria they change position every few days, tending to migrate antoriorly and this orientation may perhaps be directed by the arrangement of the scales.Cocoons, which are not deposited at 8d̀ C or below, are attached to the shell fragments with which the soles camouflage themselves and the young leeches hatch after about forty‐one days at 17d̀ C. Leeches reach maturity about twenty‐three days after finding a host and are fully grown after a further fortnight.BritishHemibdellaseem to be confuned toSoleu soleaalthough several other hosts (All Soleidae) have been recorded for this leech in the Mediterranean.

A NEW GENUS AND SPECIES OF LEECH PARASITIC ON THE FISH COTTUS BUBALIS

Five specimens of a new leech were found attached to fin‐rays of the dorsal and caudal fins of Cottus bubalis. The posterior sucker is folded laterally so that it can partially enclose a fin‐ray. These small, smooth‐skinned leeches resemble Platybdella in some respects, Abranchus in others. The coelomic system consists only of dorsal and ventral lacunae, the posterior crop caeca are separate and the dermis is narrow. There are only eighteen separate ganglia between the anterior and posterior ganglionic masses.

On a new paramphistomid trematode, Gigantocotyle lerouxi sp.n. from the stomach of the red lechwe, Onotragus leche from Northern Rhodesia

A score of these large amphistomes were found in the collection made by Dr P. L. LeRoux, to whom we wish to express our gratitude for the privilege of examining them, and to Professor J. J. C. Buckley for his interest in the work. The characteristically large posterior sucker and its muscular structure places this amphistome in Nasmark's Gigantocotyle.

The Mechanism of the so-called ‘Posterior Sucker’ of a Simulium Larva

The Mechanism of the so-called ‘Posterior Sucker’ of a Simulium Larva

The Mechanism of the so-called ‘Posterior Sucker’ of a Simulium Larva

IN NATURE of April 23, p. 599, there appears a letter from Dr. Sunder Lal Hora of the Indian Museum, Calcutta, on the subject of the mechanism of the so-called posterior sucker of the Simulium larva, in which he describes the true method of progression of this remarkable larva. In the course of his remarks, Dr. Hora quotes a passage from Tonnoir (Ann. Biol. Lacustre, 11, pp. 163-172; 1923) to the effect that this worker, “not finding any muscles inserted in the middle of the disc, doubted its utility as a true sucker and ascribed the function of attachment to the hooks alone”. He then goes on to discuss Dr. Puri's well-known paper (Parasitology, 17, pp. 295–369; 1925).

The Mechanism of the so-called ‘Posterior Sucker’ of a Simulium Larva

THE manner in which a Simulium larva fixes itself to rocks and water weeds in very rapid running water has hitherto been a matter of dispute among naturalists. Some have supposed that the so-called ‘posterior” sucker of a Simulium larva functions in the same way as does the sucker of a leech, and it is only recently that Tonnoir (Ann. Biol. Lacustre, 11, pp. 163–172; 1923), not finding any muscles inserted in the middle of the disc, doubted its utility as a true sucker and ascribed the ftunction of attachment to the hooks alone. Dr. Puri (Parasitology, 17, pp. 295–369; 1925), to whom we are indebted for a monograph, “On the Life-history and Structure of the Early Stages of Simuliidae” (1925), has demonstrated the presence of fairly strong muscles connected with the centre of the disc, and he has observed “that they contract when the larva fixes itself by its posterior end.” But he further points out that “in spite of the presence of these muscles the larva cannot fix itself effectively without the further help of the sticky salivary secretion; a fact which may mean that the saliva helps to fill up the spaces between the hooks and thus to form a complete rim all round.”

On the Life History and Structure of the Early Stages of Simuliidae (Diptera, Nematocera). Part II

(A) Life History.(1)Simulium larvaeare found in streams where the current is very fast. They are sedentary in habit and fix themselves to some support by means of their posterior sucker and sticky salivary secretion.(2) Progression is achieved by looping movements which have been described in detail.(3) Larvae feed on all kinds of fresh water animalcules, and algae.(4) Two species were reared from eggs to the adult flies for the first time in the laboratory. Abundance of food and aeration of water are two very important factors governing the rearing of these larvae.(5) There are six larval stages, each stage lasting 4–7 days. The gradual changes in the successive stages are described inS. erythrocephalumandS. aureum.(6) The sixth-stage larva, having woven its cocoon, changes into a pupa, the whole process, weaving of cocoon and pupation (described in detail), takes 75–90 minutes. Pupal life lasts 5–15 days, depending on temperature.(7) The eggs are sub-triangular in form and are laid in large patches on aquatic plants below the surface of water.(8) The first-stage larva is characterised by the presence of an egg-burster situated dorsally upon the head.(B) Morphology.(9) The larvae are eucephalous, with eleven faintly marked body-segments, three thoracic and eight abdominal, the eighth abdominal being apparently divided into two parts, the posterior carrying the anus and posterior sucker. There is a median uniramous thoracic proleg which like the posterior sucker is provided with a number of cuticular hooks.(10) The head has a number of markings which are of great taxonomic importance.(11) The head-appendages are: A pair of jointed antennae, a rounded labrum, a pair of lateral fan-shaped appendages (the premandibular organs), a pair of mandibles, a pair of maxillae each with a single-jointed palp, a hypopharynx, and a labium. These appendages have been described in detail in this paper for the first time.(12) The alimentary canal, malpighian tubules, salivary glands, muscular system and gonads are dealt with in detail.(13) The oesophageal valve has no blood sinus as has been erroneously described by previous writers.(14) A pair of dorsal glands are present above the pharynx. Their walls consist of large uninuclear cells. Dorsal glands have so far been found only inSciaraamong Dipterous larvae.(15) There is a well-developed central as well as visceral nervous system. The bilobed brain lies in the head and a chain of eleven ganglia in the body. Both the supra-intestinal and the infra-intestinal visceral systems are fully worked out for the first time.(16) There is a well-developed tracheal system with ten closed spiracles, one prothoracic, one metathoracic and eight abdominal.(17) The flattened dorsal vessel stretches from the seventh abdominal segment to the head where it ends just behind the brain. It is dilated in the seventh segment to form the heart which is provided with two pairs of ostia.(18) Nephrocytes or excretory cells (pericardial, and peri-oesophageal) are described for the first time and compared to similar structures in other Dipterous larvae.(19) A detailed description of the early stages of all the known (seventeen)1British species is given, with remarks about eleven of them, as they occur in Sweden, Norway and France.(20) The characters used for determining the species are as follows:Larva. Head markings; antennae; mandibles; submentum; anal gills; ventral papillae; and posterior sucker.Pupa. Chaetotaxy, Respiratory filaments, and Cocoon.