What are larval cestodes?
Using these characters, six basic types of larval cestodes were identified: the procercoid, an alacunate form which cannot develop further until ingested by a second intermediate host; the plerocercus, an alacunate form with a retracted scolex; the plerocercoid, an alacunate form with an everted scolex; the merocercoid …
What are the characteristics of cestodes?
Cestodes are long, flat, ribbon-like organisms commonly called tapeworms. The head, or scolex, has one or more hooked suckers for firm attachment to the host. Behind the head is the neck which is the growing region. The body consists of segments, each containing reproductive organs.
What is an example of class cestoda?
Cestodaria
EucestodaCaryophyllideaTetrabothriidea
Tapeworms/Lower classifications
How many species of cestoda are there?
6000 species
Diversity and habitat. All 6000 species of Cestoda are parasites, mainly intestinal; their definitive hosts are vertebrates, both terrestrial and marine, while their intermediate hosts include insects, crustaceans, molluscs, and annelids as well as other vertebrates.
What is the infective stage of cestodes?
Within this crustacean intermediate host, the larval tapeworm (procercoid) develops. If the copepod is then ingested by a suitable fish, the larva migrates to the host’s body cavity and develops to the plerocercoid stage, which is infective to the definitive host (including humans).
What are the two orders of cestodes?
Cestodes (tapeworms) include flatworms belonging to the phylum Platyhelminthes, class Cestoidea, subclasses Cestodaria (two orders) and Eucestoda (sixteen orders), and about fifty-nine families.
How do the larval forms of the trematodes and the cestodes differ and how do their life cycles differ?
Cestodes are tape-like and segmented in shape, have a head with suckers and possibly hooks, and lack a digestive tract. Trematodes are leaf-like and unsegmented, lack hooks entirely, and have an incomplete digestive tract. Generally, cestodes require two hosts and trematodes need three to complete their life cycles.
What is the life cycle of cestodes?
All cestodes cycle through 3 stages—eggs, larvae, and adults. Adults inhabit the intestines of definitive, or final, hosts, which are mammalian carnivores, including humans. Several of the adult tapeworms that infect humans are named after their main intermediate host (the fish, beef, and pork tapeworms).
Do all cestodes have Proglottids?
All cestodes have a scolex and neck and can have mature, immature, or gravid proglottids. Mature forms have male and female sex organs. saginata are pork and beef tapeworms, respectively, whereas Echinococcus granulosus and E. multilocularis are dog tapeworms.
What are the common host of cestodes?
Echinococcus eggs from dog or fox fur cause human hydatid disease (humans are the intermediate host; canids are the definitive hosts). Reinfection with adult tapeworms is common; second infections with larvae are rare.
How do the larval forms of the trematodes and the cestodes differ?
Cestodes are tape-like and segmented in shape, have a head with suckers and possibly hooks, and lack a digestive tract. Trematodes are leaf-like and unsegmented, lack hooks entirely, and have an incomplete digestive tract.
What is the larval stage of Taenia Solium called and what animal is this larva normally found in?
Cysticercosis is the disease associated with the development of the larval form (cysticercus) of the pork tapeworm, Taenia solium, within an intermediate host.