The outer segmentation of the trunk (always 13 segments) of the kinorhynchs is also seen in the serial repetition of ventral double ganglia suggests affinities with the next group we will study.on most segments. No kinorhyncha fossils have yet been found. Notable characteristic:spiny cuticle divided into a fixed number of units.
![]() The blood vascular system is a closed type. Respiration occurs through moist skin or gills of parapodia and head. Digestion is entirely extracellular. The alimentary canal is straight tube-like, complete, extending from mouth to anus. Coelomic fluid with cells or corpuscles. Mostly well-developed in leeches. Receptor organs include tactile organs, taste buds, statocysts, photoreceptor cells and sometimes eyes with lenses in some. The nervous system consists of a pair of cerebral ganglia brain and double ventral nerve cord having segmentally arranged ganglia and lateral nerves in each segment. Excretion is by metamerically disposed coiled tubes nephridia which communicate the coelom to the exterior. Download free kumpulan game psp iso rar for macLarva, when present is a trochophore is characteristics in case of indirect development, while in others this stage is passed through development.Class 1- Polychaeta (Gr., poly=many , chaeta=bristles/hair) Their development is direct in monoecious form but indirect in dioecious form. Hermaphroditic or sexes separate cleavage spiral and determinate dioecious or unisexual form also present. The coelom is spacious usually divided by intersegmental septa. Cirri or branchiae or both may be present for respiration. Head consists of prostomium and peristomium and bears eyes, tentacles cirri, and palps. ![]() Body made of 2 or more regions, with unlike segments and parapodia. Examples: Nereis, Aphrodite, Polynoe, Phyllodoce, Tomopteris, Syllis, Eunice, Histriobdella. Pharynx protrusible, enlarged and usually with jaws and teeth. Parapodia, provided with cirri, are equally developed throughout. Feeding on plankton or organic detritus. Gills, when present, localized to the anterior segments. Pharynx non-protrusible without jaws and teeth. Serial Repetition Of Segments Is A Defining Characteristic Of Which Worm Phylum? Trial Or SomeHead indistinct, without sensory organs. Body with conspicuous external and internal segmentation. Mostly terrestrial or some freshwater forms. The gizzard is poorly developed, non-muscular or absent. Fertilization external (in cocoon) no larval stage. The pharynx is not eversible and without jaws. Asexual reproduction is not known. Vasa differentia are elongated extending over 3 or 4 segments. Female genital aperture is always on the 14 th segment and the male pore lies a few segments behind them. The clitellum is composed of two or more layers of cells and never begins before twelfth segments. Setae are managed in a lumbricine Manner. Male reproductive openings lie in front of female reproductive openings. The body consists of a fixed number of segments (33). The body is elongated and usually flattened and dorso-ventrally or cylindrical. Few are marine, freshwater or terrestrial. Mostly ectoparasitic, blood-sucking or carnivorous. The mouth opens on the ventral surface on anterior suckers, while anus opens dorsal to the posterior suckers. Both anterior and posterior ends of the body with ventrally situated suckers. Segmentation external without internal septa. Double rows of setae are present in 5 anterior segments. They are primitive, without anterior suckers, proboscis, and jaws. Mostly parasitic on the fins of salmon fishes. Development is direct without a free-swimming larval stage. Hermaphrodite with one male and one female gonopore. Each typical body segment consists of 3,6 or 12 rings. Parasites on snails, frogs and fishes, marine and freshwater form. Examples: a single genus and species ( Acanthobdella) parasitic on salmon. Nephridial opening situated on the surface between the segments. The vascular system consists of the dorsal and ventral vessels. Each typical body segment consists of 5 rings or annuli. Ectoparasitic blood-sucking leeches. Freshwater and terrestrial form. Examples: Placobdella, Helobdella, Piscicola, Branchellion. Blood vascular system separated from coelomic sinuses. Pharynx non- protrusible. Terrestrial and aquatic. Examples: Hirudo, Hirudinaria, Haemadipsa, Herpobdella.
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