212 



MESOZOA THROUGH ENTOPROCTA: 



torn muck of colder to arctic seas; sexes separate, de- 

 velopment essentially direct but involving a larval 

 stage. 



ENTOPROCTA (Moss Animals) 



Diagnosis: symmetry bilateral; body unseg- 

 mented; pseudocoelomates with a looped digestive 

 tract; stalked, attached animals with a circlet of 

 cilated tentacles around the mouth (lophophore); 

 solitary or colonial with individuals not more than 

 0.2 inch in length and colonies of some size; super- 

 ficial resemblance to coelenterates (hydroids) and 

 seaweeds, but are rough to the touch; closer re- 

 semblance to Ectoprocta and formerly considered 

 part of that phylum, but only the individual Ento- 

 procta stalks can move independently; mostly 

 marine, one conspicuous fresh-water species in the 

 eastern and central United States (Figure 12.15). 



Figure 12.15 Sorentsio, an entoproct moss onimol: A, natural size of 

 colony; B, magnified individuals; note the straight stalks that are in- 

 dependently movable {absent in Ectoprocta). 



Although entoproct moss animals possess a lopho- 

 phore, they are not part of that group (see p. 213). 

 This is the case because Lophophorata is merely 

 a term of convenience to designate a particular group 

 of animals with a true body cavity. It has already 

 been emphasized that entoprocts do not possess a 

 coelom, but rather, that they have a pseudocoel. 



The name Entoprocta points out another diflference 

 between entoprocxs and ^doprocts. The entoprocts 



have the anus inside the lophophore and the ecto- 

 procts have theirs outside the lophophore. 



Entoprocts are either biparental or have both sex 

 organs in one individual (hermaphroditic). After 

 fertilization, the egg develops into a motile larva 

 which transforms to the adult form. This larva, like 

 that of many other phyla, is the only means by which 

 the animals are disseminated; the adults are strictly 

 sedentary creatures found growing on other animals 

 or objects in water. 



SELECTED READINGS 



Barnes, R. D., 1963. Inverkhrate ^oology. W. B. Saunders 

 Co., Philadelphia. 



Buchsbaum, R., 1948. Animals without Backbones, rev. ed. 

 The University of Chicago Press, Chicago. 



and L.J. Milne, 1960. The Lower Animals. Double- 

 day & Co., Garden City, N.Y. 



Edmondson, W. T., ed., 1959. Ward and Whipple's Fresh- 

 water Biology. 2nd ed. John Wiley & Sons, New York. 



Hyman, L. H., 1940. The Invertebrates. Vol. 1: Protozoa 

 through Ctenophora. McGraw-Hill Book Co., New York. 



,1951. The Invertebrates. Vol.2: Platyhelminthes and 



Rhynchocoela. McGraw-Hill Book Co., New York. 



, 1951. The Invertebrates. Vol. 3: Aschelminthes and 



Entoprocta. McGraw-Hill Book Co., New York. 



Johnson, M. E., and H. J. Snook, 1927. Seashore Animals of 

 the Pacific Coast. The Macmillan Co., New York. 



MacGinitie, G. E., and N. MacGinitie, 1949. .Natural 

 History of .Marine Animals. McGraw-Hill Book Co., 

 New York. 



Miner, R. W., 1950. Field Book of Seashore Life. G. P. Put- 

 nam's Sons, New York. 



Palmer, E. L., 1949. Fieldhuok of .Natural History. McGraw- 

 Hill Book Co., New York. 



Pennak, R. W., 1959. Fresh-water Invertebrates of the L'nited 

 States. The Ronald Press Co., New York. 



Ricketts, E. F., and J. Calvin (edited by J. VV. Hedgpeth), 

 1952. Between Pacific Tides. 3rded. Stanford University 

 Press, Stanford, Calif. 



Tinbergen, N., 1953. .Social Behavior m .Animals: With Spe- 

 cial Reference to I'ertebrata. John Wiley & Sons, New 

 York. 



Vessel, M. F., and E.J. Harrington, 1961. Common .Native 

 .■inimals. Chandler Publ. Co., San Francisco, Calif. 



