Difference between revisions of "Pseudophyllidea"
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| − | Pseudophyllidean tapeworms have a scolex with four longitudinal grooves. | + | *Pseudophyllidean tapeworms have a scolex with four longitudinal grooves. |
| − | They have a genital pore which is centrally placed on each segment. | + | *They have a genital pore which is centrally placed on each segment. |
| − | The eggs and life-cycle have some similarity to that of the trematodes. | + | *The eggs and life-cycle have some similarity to that of the trematodes. |
| − | The Pseudophyllidean egg shell is thick, brown and operculate. | + | *The Pseudophyllidean egg shell is thick, brown and operculate. |
| − | The Pseudophyllidean life-cycle uses two intermediate hosts – the coracidium, which emerges after hatching, must first be ingested by a crustacean. A larval procercoid develops within the body cavity of the crustacean. If the crustacean is then eaten by a freshwater fish, the procercoid is liberated and develops into a second larval stage, a plerocercoid, within the muscles of this new host. The plerocercoid possesses the characteristic scolex – it is only this stage that is infective to the final host. | + | *The Pseudophyllidean life-cycle uses two intermediate hosts – the coracidium, which emerges after hatching, must first be ingested by a crustacean. A larval procercoid develops within the body cavity of the crustacean. If the crustacean is then eaten by a freshwater fish, the procercoid is liberated and develops into a second larval stage, a plerocercoid, within the muscles of this new host. The plerocercoid possesses the characteristic scolex – it is only this stage that is infective to the final host. |
| − | There are no pseudophyllideans of importance in the UK, but some are of significance in tropical or sub-tropical areas (for example Spirometra), and in sub-arctic regions (for example Diphyllobothrium). | + | *There are no pseudophyllideans of importance in the UK, but some are of significance in tropical or sub-tropical areas (for example Spirometra), and in sub-arctic regions (for example Diphyllobothrium). |
Revision as of 20:50, 21 December 2008
- Pseudophyllidean tapeworms have a scolex with four longitudinal grooves.
- They have a genital pore which is centrally placed on each segment.
- The eggs and life-cycle have some similarity to that of the trematodes.
- The Pseudophyllidean egg shell is thick, brown and operculate.
- The Pseudophyllidean life-cycle uses two intermediate hosts – the coracidium, which emerges after hatching, must first be ingested by a crustacean. A larval procercoid develops within the body cavity of the crustacean. If the crustacean is then eaten by a freshwater fish, the procercoid is liberated and develops into a second larval stage, a plerocercoid, within the muscles of this new host. The plerocercoid possesses the characteristic scolex – it is only this stage that is infective to the final host.
- There are no pseudophyllideans of importance in the UK, but some are of significance in tropical or sub-tropical areas (for example Spirometra), and in sub-arctic regions (for example Diphyllobothrium).