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when an abalone IHaliotis) is dislodged from its 

 rocky support, it tends to curl the edges of its broad 

 foot, here seen from below. (California. Ralph Buchs- 

 baum) 



Until the heavy growth of hvdroids, moss animals, and 

 seaweeds is cleaned from the red abalone {Halintis 

 nifescens), the attractive shell cannot be seen, al- 

 though its breathing holes remain unobstructed. (Cal- 

 ifornia. J. A. Aplin) 



water or on land. Curiously enough, the prosobranch 

 snails are either male or female, whereas the opis- 

 thobranchs and pulmonates are hermaphroditic. 



PROSOBRANCHS 



Abalones (the word has four syllables, the final e 

 being sounded ) are also called ear shells or ormers. 

 They are widespread vegetarians with definite pref- 

 erences in location and habits. Man enjoys the big 

 muscle attached to an abalone's shell so much that 

 these animals are always in danger of extermination. 

 Those used for food on the island of Guernsey in the 

 English Channel (Haliotis tubeniilatiis) have virtu- 

 ally vanished. In California the large abalones of sev- 

 eral kinds were in similar danger until minimum size 

 limits were enforced on residents and shipment of 

 both abalone meat and the handsome, iridescent 

 shells from the state were forbidden. 



Shells of the red abalone Haliotis nifescens are al- 

 most always encrusted heavily by hydroids, bryo- 

 zoans, and plants. Water passing the abalone's gills 

 emerges through three or four open holes in the shell 

 as the animal browses on sea lettuce and kelps. The 

 red abalone reaches breeding age at six years and a 

 length of 4 inches. Minimum size for legal possession 

 is now 7 inches, which may correspond to about 

 twelve years of age since one thirteen-year-old speci- 

 men kept under observation was 8 inches long. Red 

 abalones with 10-inch shells are now rare except in 

 collections. 



The green abalone H. fiilgens has a flatter shell 

 with six open holes and very little growth of other 

 life on its shell. Yet it resembles H. nifescens in 

 clinging to rock ledges where the water is fifty to 

 seventy feet deep and consequently fairly free of 

 wave action. The black abalone H. cmcherodii, by 

 contrast, is a surf-dweller, in the cracks of rocks 

 through which waves plunge. Its shell is regularly 

 clean and shining, with from five to eight perfora- 

 tions. Large numbers reach the legal minimum size 

 for harvesting — SVi inches. 



Apparently the black abalone feeds on micro- 

 scopic plants, whereas the others take larger fare. 

 The green abalone is particularly quick when a bit of 

 seaweed strikes the long tentacles projecting under 

 the mantle edge. It whirls and uses the anterior end 

 of its foot to clamp the seaweed against the rock until 

 the mouth can be brought to bear and the radula can 

 rasp the plant into pieces small enough to swallow. 

 This same whirling movement is a protection against 

 starfish, one that is successful unless the abalone is 

 too small or the sea star too large. 



A limpet has the reputation of being able to cling 

 to a rock more tightly than an abalone — more tightly, 

 in fact, than any other animal. But an undisturbed 

 limpet holds just tightly enough to keep waves from 

 dislodging it. A sudden push from the side usually 



178 



