304 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Paranemertes bioceUata, Amphiporus texanus, and 

 Cerebratulus ater are widely distributed on the 

 Atlantic coast, and 4 of them, namely, Tubulanus 

 pellucidus, Zygeupolia rubens, Zygonemerfes vires- 

 cens, and Amphiporus crv^ntatus occur also on the 

 Pacific coast but not in Europe; 2 others, Car- 

 cinonemertes carcinophila and Tetrastfmma vermi- 

 culus are found on European coasts but not in 

 the Pacific; Oerstedia dorsalis, Tetrastemma candi- 

 dum, and Malacobdella grossa are circumpolar, 

 inhabiting European shores as well as both the 

 Atlantic and Pacific coasts of North America, 

 while the remaining 5 species, Carinoma trema- 

 phoros, Lineus socialis, Micrura leidyi, Cerebra- 

 tulus lacteus, and Amphiporus ochraceus are known 

 only from the Atlantic and Gulf coasts. Para- 

 nemertes bioceUata and Cerebratulus texanus have 

 been found only on the northern Gulf coast, while 

 Cerebratulus ater is reported from off the Cape of 

 Florida and at Curasao. 



For comparison, it may be noted that 11 of the 

 53 species found on the Atlantic coast are identical 

 with species in European waters, while 12 of the 

 Atlantic coast species occur also on the Pacific 

 coast, and 2 of these extend also to Japan. No 

 less than 18 of the species found on the Pacific 

 coast are thought to be identical with well-known 

 European species, and others are closely similar 

 (Coe 1943). The nemertean fauna of Bermuda 

 resembles more closely that of Europe and Madeira 

 than that of the American coast in spite of the 

 proximity of the latter. 



As a general rule, the invertebrates in the Gulf 

 are much smaller when mature than are the mem- 

 bers of the same species in more northern an4 

 colder localities. This applies likewise to the 

 nemerteans. To anyone familiar with the species 

 on the New England coast the representatives of 

 the same species in the Gulf appear to be dwarfs. 

 Species living among Bryozoa, algae, and other 

 growths in the intertidal zone farther north are 

 more commonly found beyond the low-tide level 

 in the Gulf. 



REPRODUCTION AND REGENERATION 



If ripe individuals of both sexes are available, 

 nearly all the species, but especially Cerebratulus 



lacteus, are suitable for the study of embryological 

 development. From a large ripe female of C. 

 lacteus many thousand eggs may be obtained, and 

 these usually develop rapidly into pilidium larvae 

 after artificial insemination. Most of the species 

 restore by regeneration the posterior end of the 

 body after injury or removal. Lineus socialis 

 provides an example of asexual reproduction by 

 fragmentation and is unexcelled for the study of 

 the complete regeneration of minute fragments of 

 the body. Almost any small piece of the body, 

 provided it contains a portion of one of the nerve 

 cords, will regenerate into a minute replica of the 

 original worm (Coe, 1929-34). 



ECOLOGY 



Most of the species on the Gulf coast are found 

 biu-rowing in the sand or mud in the low intertidal 

 zone and below to areas where the depth of water 

 is 10 meters or more. Others live beneath stones 

 or among dead shells, while many of the smaller 

 species occur among Bryozoa, algae, and other 

 growths in the intertidal zone and below. 



FOOD 



Nemerteans are usually carnivorous, feeding on 

 a great variety of worms, crustaceans, mollusks, 

 and other small, soft-bodied animals. To secure 

 their prey they are furnished with highly special- 

 ized sense organs and most of them with a long, 

 eversible proboscis. This organ is a formidable 

 weapon, provided in some species with one or 

 more acutely pointed stylets which puncture dnd 

 paralyze the prey, allowing the soft parts to be 

 sucked into the mouth. In species without 

 stylets the proboscis, which is covered with a 

 tenacious secretion, can be coiled about the prey, 

 thereby holding it tightly until it can be drawn 

 into the mouth. Only one of the species, Mala- 

 cobdella grossa at present known from the Gulf is 

 commensal living in the mantle cavity of clams. 

 Another species, Carcinon.emertes carcinophila, 

 sucks the blood in the gills and the substance of 

 the eggs of various species of crabs and is therefore 

 truly parasitic. 



