Diversity of Polychaeta
Errant Polychaetes
Free-living forms. (Active lives)
well-differentiated head with prominent sense organs.
They have well-developed parapodia.
They can be crawling over the surface using parapodia & setae.
Dorsoventrally flattened body.
Well-developed longitudinal muscle(thin circular muscle)
They are predatory carnivores, but some are herbivorous & scavengers.
They possess an eversible pharynx equipped with jaws & teeth.
They found on the substrate
Neris and Glycera have elongated bodies.
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| Glycera |
Aphrodite (Sea mouse)-Very short & broad body
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| Aphrodite |
Tomopteris- Their parapods are expanded into fan-like structures. They use to swimming.
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| Tomopteris |
sedentary Polychaetes
Mainly found on the bottom of the substrate.
Few tube dwellers form tubes.
Their cross-section is circular.
Their parapodia are reduced or modified.
Setae in parapodia use to digging.
They have poorly developed sense organs.
Some of them lack proboscis.
Some have long tentacles and palps that form fan like structure in the anterior end.
this structure serves to catch their food & act as gills.
They are suspension feeders or deposit feeders.
Sedentary Polychaetes are mainly of 2 categories:
1.Burrownig forms.
2.Tube dwelling.
Burrowing forms
Usually occupy verticle or u-shaped burrows.
Some of them are carnivores, feeding on animals they while burrowing.
They have a non-muscular pharynx.
E.g: Arenicola
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| Arenicola |
Some forms lack a muscular pharynx. But on feed on the materials by using tentacles around the mouth.
E,g: Amphitrite
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| Amphitrite |
Tube dwelling forms
Similar to the burrowing forms.
They live in a burrow, build tubes.
The tube protects them.
Some tube-dwell selectively feed using their tentacles.
Pectinaria
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| Pectinaria |
A few sedentary tube dwellers non-selectively on deposited material.
Clymenella
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| Clymenella |
The majority of tube-dwelling forms are highly specialized for filter-feeding.
Sabella
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| Sabella |
Serpula
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| Serpula |
Chaetopterus - The beating of fans on the posterior body creates the water current.
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| Chaetopterus |
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