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8 Cards in this Set
- Front
- Back
What is Phylum Annelida? |
Segmented worms |
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General characteristics? |
•Bilaterally symmeterical •True coelom filled with true coelomic fluid. The only phylum with true coelom. (Coelomates) • Has advanced blood circulatory system. •Excretion: Nefridia •Segments are divided by septums. And each segment is called a metamer. •Metamerism: condition of segmentation. |
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Body structures of Annelids? |
3 parts: ○ head= prostomium (brain+ sense organ) ○segmented body section ○posterior end= pygidium, where anus is situated. •new segments are formed in front of the pygidium. Thus, the oldest segment is next to the head. •intestine, blood vessels and nerve chords extends throughout the body. • some species, bristle-like structure (chaetae) can be found on the body |
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3 classes of Phylum Annelida? |
• Polychaetae (seaworm) =the most chaetae •Oligochaetae (earthworm) = less chaetae •Hirudinea (leech) =chaetae absent |
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Polychaetae species and its characteristics? |
Neries sp. (Seaworm)
Dioecious: having female and male reproductive structures in separate bodies.
Has distinct head (eyes, antenna,palp)
Has parapodia at each metamer: for locomotion and gaseous exchange.
Has bristle(chaetae) at parapodia. |
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Reproduction of neries sp. ? |
Both male and female gametes are released into the sea. The eggs and sperms are carried by the current, meet up and fertilises. The eggs hatch into larvaes callled trochophore before becoming adults. |
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Species under oligochaetae and the characteristics? |
Pheretima sp. (Earthworm)
Has less chaetae.
Terrestrial hermaprhodite living in moist soil.
No distinct head.
Prostomium shaped like a cone.
Has fine bristles(chaetae) around the body. |
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Evolution of Annelids living on land? |
Believed to have been living in the sea since the start till now for polychaetae. |
