Annelida

Charateristics

• nervious system has gian axons- tranmit nerve impulses faster, for faster responses
• coelom
• closed cirulatory system
• true segmentation- repeating series of body units
• units may or may not be similar to one another (in insects segments may be fused or have specilized functions)
• septa- walls that create segments
• most are monecious (hermaphodites)

disection of Lubricus

Test yourself

Three Classes

Oligochaeta - The class Oligochaeta includes the megadriles (earthworms), which are both aquatic and terrestrial, and the microdrile families such as tubificids, which include many marine members as well.

have longitudinal mussles

segments appear similar

earth worms create tunnels

Polychaeta - This is the largest group of the Annelids and majority are marine. All segments are identical each consisting a parapodia. The parapodia are used for swimming, burrowing and feeding current.

• Most are marine
• Bristles extend from pared, fleshy parapids on each segment
• head end is specialied
• bear bristles called setae made of chiton
• examples
  • sandworm
  • clam worm
  • lugworm

Leeches (Hirudinea) - These include both bloodsucking external parasites and predators of small invertebrates.

Predators and parasites

less obvious body segment

most have sharp jaws

beneficial for

reconstructive surgery

clot-busting- anitcoagulant properites in secreted saliva

Slide 50 Leech

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