Tree and most traits from (Nielson 1994 p. 143), and Brusca & Brusca (1990 p. 432).

                          ==3*== SubCl. Errantia (errant marine segmented worms)
       ==2*=Polychaeta==|
       |                  ==4*== SubCl. Sedentaria (sedentary marine segmented worms)
<<=1*==|
       |   =====6*============== Oligochaeta (earthworms & relatives)
       =5*=|
           |         ==8*======= Acanthobdellida (primitive leech-like annelids)
           =====7*===|
                     ==9*======= Hirudinea (true leeches)

1:a) body with many segments each bearing a separate coelom**, b) simple prostomium**, c) multiciliated cells**, d) chitinous setae in setal sacs**, e) separate sexes, gametes from body wall (no permanant gonads), f) segmented ventral nerve cord**, g) closed circulatory system with capillaries and contractile vessels or hearts, h) metanephridia with nephrostome opening in segment anterior to that of the nephridial tubule
2: a) extensive setae, b) parapodia, c) gametes from body wall (no permanant gonads)**, d) complex prostomium
3: a) parapodia well developed, b) numerous similar segments, c) pharynx with jaws (most)
4: a) parapodia reduced or absent, b) segments usually differ in form, c) jaws usually absent
5: a) few setae, b) parapodia lost, c) hermaphroditic, d) clitellum that produces the cocoon in which eggs are laid, e) permanant gonads
6: a) simple prostomium**, b) no parapodia**, c) calciferous glands of esophagous, d) typhlosole (earthworms)
7: a) single large coelom due to loss of septae between body segments, b) fixed number of body segments, c) setae restricted to a few anterior segments, d) posterior sucker (no anterior sucker), e) superficial annuli in body wall
8: a) segmented coelom in anterior-most 5 segments (no anterior sucker)**; b) setae restricted to a few anterior segments**, c) body of 30 segments
9: a) anterior sucker, b) body of 34 segments, c) coelom unsegmented, d) no setae

Back to Zool 250 version of tree for animal phyla

Back to Zool 250 Home Page