200 



MESOZOA THROUGH ENTOPROCTA: 



I 



Mi 



11 



Figure 12.6 Hydrozoan types. Order Hydroidea: A, P/umu/or/o, a 

 colonial hydroid or sea feather; B, Obelia, a colonial hydroid. Order 

 Hydrocorolina: C, Stylanlheca, a hydrocoral; D, Miitepora, o hydro- 

 coral {an enlargement would resemble Sty/ontheco). Order Trochylino; 

 E, Gonionemus, an hydromeduson. Order Siphonophoro; F, Physalia, 

 the Portuguese man-of-war; G, Velella, the purple sailor. 



ORDER SIPHONOPHORA (Siphonophores) 



Diagnosis: free-swimming or floating colonies con- 

 sisting of modified medusoid and polypoid individuals 

 of many sorts; marine. 



Siphonophores might be likened to floating, living 

 fortresses. Physalia, the Portuguese man-of-war, has 

 the most powerful sting of all coelenterates. Hospital 

 treatment often is necessary for swimmers who be- 

 come entangled in its tentacles. However, the only 

 real danger to man is that the sting might affect 

 swimming to the point that one could drown. Phy- 

 salia is seldom found on the Pacific Coast, but is fairly 

 regularly encountered along the Gulf of Mexico and 

 sometimes farther north along the Atlantic Coast. 

 The common Pacific Coast species is ( elella lata, the 

 purple sailor. This floating species sometimes is cast 

 upon California beaches in great numbers. In many 

 areas it is improperly called the Portuguese man- 

 of-war. On some purple sailors one might find at- 

 tached gooseneck barnacles. 



find a ^ to % inch species that is made conspicuous 

 by its reddish-brown sex organs; the "bell" and 

 numerous tentacles tend to be invisible when the 

 animal is in the water. 



CLASS SCYPHOZOA (Jellyfishes) 



Diagnosis: solitary umbrella- or bell-like animals, 

 polyp form reduced or absent; medusae without a 

 "shelf" (velum); material between inner and outer 



