LOWER ANIMALS 



201 



tissue layers very thick and jelly-like; medusa margin 

 regularly with eight notches that contain sense or- 

 gans; strictly marine; all large medusae belong to 

 this class (Figure 12.7). 



ORDER STAUROMEDUSAE (Sessile Jellyfishes) 



Diagnosis: attached, upside down, usually to kelp 

 or eelgrass; attachment is not permanent, and ani- 

 mals can crawl along the substrate; top of umbrella 

 is drawn out into an attachment stalk; common spe- 

 cies are about an inch or more in diameter and are 

 most likely found on eelgrass in quiet waters such 

 as bays. 



ORDER CUBOMEDUSAE (Jellyfishes) 



Diagnosis: free-swimming; umbrella cubical, with 

 margin bent inward and with four, or four groups of, 

 tentacles; United States species are found along At- 

 lantic shores; mostly in subtropical to tropical waters; 

 tend to be fish predators. 



ORDER CORONATAE (Jellyfishes) 



Diagnosis: free-swimming, umbrella margin 

 scalloped and separated from umbrella proper by a 

 circular furrow; mostly deep-water forms. 



ORDER DISCOMEDUSAE (Jellyfishes) 



Diagnosis: free-swimming; four corners of mouth 

 prolonged into grooved oral arms, oral arms single 

 (four) or double (eight); tentacles none to many; en- 

 countered mostly in coastal waters. 



The true jellyfish are free-living and free-floating 

 animals. They can swim in a slow jerky manner by 

 sudden contractions of the umbrella or bell. Jelly- 

 fish feed in much the same way as do other coelenter- 

 ates. Prey running into the tentacles is stung and 

 moved to the mouth by the tentacles. Some jellyfish 

 feed from the bottom. This bottom feeding is ac- 

 complished by the animal's lying upside down and 

 drawing prey to the mouth by means of a current 

 created by pulsating the bell. Other jellyfish 

 assume an expanded, upside down position and 

 slowly sink, capturing their prey on the way down. 



These animals are most likely to be seen from a 

 boat. Some larger species that may be observed are 



solid-colored yellow, orange, or brown; or pinkish 

 or purplish with dark purple or purplish-black 

 stripes. The smaller forms, about fist size or smaller, 

 tend to be transparent; however, pigment usually 

 makes the sex organs visible. 



CLASS ANTHOZOA 



Diagnosis: solitary or colonial; strictly polyps, no 

 medusae known; polyps with vertical membranes 

 partitioning the gastrovascular cavity; strictly 

 marine (Figure 12.7). 



Subclass ALCYONARIA 



Diagnosis: with eight, branched tentacles; colonial; 

 with an internal skeleton. 



ORDER STOLONIFERA (Stolon Corals) 



Diagnosis: polyps originate separately from a 

 common, flattened, creeping tube (stolon) or mat; 

 skeleton of spines occurring separately or fused into 

 tubes; mostly in deeper water, intertidal species form 

 low, encrusting, spreading growth on rocks, shells, 

 or other hard substrates; polyps usually contracted 

 to small pinkish mounds so the tentacles are usually 

 not visible; coral base and ribbon-like stolons help 

 separate these animals from simple ascidians (Chor- 

 data) in identification. 



ORDER TELESTACEA (False Sfolon Corals) 



Diagnosis: colonial, of simple or branched stem 

 bearing lateral polyps; each colony stem grows erect 

 from a somewhat stem-like creeping base; internal 

 skeletal parts united or not. 



ORDER ALCYONACEA {Soft Corals) 



Diagnosis: lower polyp parts fused into a fleshy 

 mass, but some polyps reach the colony base; skeletal 

 parts neither united nor axial; mostly a warm-water 

 group. 



ORDER GORGONACEA {Horny Corals) 



Diagnosis: colony plant-like, originating from a 

 single base; supported by a central coral skeleton, 

 horn-like material, or both; polyps originate from 



