Lecture 18 – Annelids, Onychophora

Lecture 18 – Annelids, Onychophora -...

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Lecture 18 – Annelids, Onychophora A. Annelida (means “little rings”) 1. Segmented worms - On the outside you see the grooves (numbered) - On the inside there are septa (partitions between each segment) 2. Specialization - Now that you have segmentation you can specialize certain areas of the body In higher organisms like us we are so advanced we lose the segmentation In worms this is primitive (the beginning of specialization) and it is metamerism (parts are repeated in the segments), not complex segmentation 3. Hydrostatic skeleton – fluid-filled 4. Setae – structures for motility (how they divide the classes up); bristle-like 5. Examples a. Polychaeta (fig 30-11)- means “many bristles per segment” – they are marine and there are many bristles found on each segment b. Oligochaeta (fig. 30-12) – means “few bristles per body segment,” only have 4 pairs per segment Example: Lumbricus terrestris – the common earthworm Freshwater or moist terrestrial – need a lot of moisture 100 segments (about 20 centimeters long)
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This note was uploaded on 05/30/2008 for the course BS 131 taught by Professor Smith during the Spring '08 term at University of the Sciences in Philadelphia.

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Lecture 18 – Annelids, Onychophora -...

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