PHYLA OF LESSER SIGNIFICANCE 269 



separate phylum. The annelid-like characteristics of Peripatus include a 

 thin cuticle which covers the body, paired nephridia in each segment, a 

 dorsal blood vessel, and ciliated reproductive organs. These are char- 

 acteristics not found in the arthropods. The arthropod-like characteristics 



External ring 

 Papilla 





Anus 

 College Zoology, Hegner, The Macmillan Company 



Fig. 18.5. Peripatus. This animal bears characteristics of the annelid worms and 

 also the arthropods and seems to form a connecting link between the two. 



which are not found in annelids include claws on the appendages, trachea 

 for respiration, and blood sinuses. These features of Peripatus cause it 

 to be considered as evidence of annelid ancestry of the arthropods. 



Classification and Derivation of Scientific Words 



Phylum Ctenophora (Gr. ktenos, comb; phoros, to bear; these animals bear 



eight rows of comb-like bodies). Comb jellies, or sea walnuts. 

 Phylum Rotifera (L. rota, wheel; jerre, to bear; beating cilia on anterior 



discs resemble turning wheels). Wheel animals, or rotifers. 

 Phylum Gastrotricha (Gr. gaster, stomach ; trick os, hair ; have tracts of cilia 



on the ventral surface). 

 Phylum Bryozoa (Gr. bryon, moss; soon, animal; resemble moss). Moss 



animals. 

 Phylum Phoronidea (Gr. Phoronis, from Greek mythology, a goddess that 



was changed into a heifer by Zeus). 

 Phylum Brachiopoda (Gr. brachion, arm; pons, foot; when first discovered 



it was thought that the coiled arms w r ere extended out to serve as feet). 

 Phylum Chaetognatha (Gr. chaite, bristle; gnathos, jaw; there are bristles 



on the jaws that aid in capturing food). 

 Phylum Nemertea (Gr. Nemertes, one of the Nereid nymphs in Greek 



mythology). The ribbon worms. 

 Phylum Onychophora (Gr. onus, claw; pherein, to bear; they bear claws 



on their legs). 



