xi ECONOMIC USES COMMENSALISM 297 



One of the commonest baits used for certain fish, as all who 

 have done any sea-fishing off the piers of our coasts know, is the 

 common lug-worm (Arenicola marina}, whilst Nephthys caeca and 

 Nereis fucata are also used in some places : and for whiting 

 Xereis cidtrifera and N. diversicolor. Marphysa sanguinea, 

 known to the fishermen in some parts as " varme," is less fre- 

 quently used. 



A peculiar worm Palolo viridis is used as food by the 

 natives of Samoa and Fiji. The worm is similar to our Eunicid 

 Lysidice ninetta, and lives in fissures among corals on the reefs, 

 at a depth of about two fathoms. At certain days in October 

 and November they leave the reefs and swim to the shores of 

 the above islands, probably to spawn ; and this occurs on two 

 da}s in each of the above months the day on which the moon 

 is in her last quarter, and the day before. The natives, who call 

 the worm " Mbalolo," give the name " Mbalolo lailai " (little) to 

 October, and " Mbalolo levu " (large) to November, thereby in- 

 dicating the relative abundance of the worms in these two 

 months. The natives eat them either aliva or baked, tied up in 

 leaves ; and they are esteemed so great a delicacy that presents 

 of them are sent by the chiefs who live on shore to those living 

 inland. A dark green-blue Phyllodocid, which is called " A'oon," 

 occurs in abundance off Mota Island, amongst the New Hebrides, 

 has similar habits, and is also eaten. 1 



Associated Worms. A considerable number of worms live in 

 association with other animals, either as commensals or as para- 

 sites, and it is not in every case possible to decide in what relation 

 the two animals stand. Labrorostratus parasiticus, a Eunicid, is 

 parasitic in the body-cavity of Odontosyllis ctenostomatus (Fig. 

 158); such an association between two members of the same 

 group of animals is peculiar ; but still more exceptional is the 

 occurrence of Haematocleptes terebellides, as a parasite in Marphysa 

 sanguinea, for both parasite and host are members of the same 

 family, the Eunicidae. Another Eunicid, Oligognathus bonelliae, 

 occurs in the body-cavity of the Gephyrean Bonellia. 



The Polynoid Acholoe astericola and the Hesionid Opliio- 

 dromus flexuosus occur as ectoparasites (or perhaps commensals) 

 in the ambulacral grooves of the starfish Astropecten aurantiacus. 

 An Amphinomid is stated to live in the branchial chamber of 



1 For an account of these worms see M'lutosh, loc. cit. p. 257. 



