FISHERY BULLETIN: VOL 77, NO. 3 



tested with C. regal is were <20 mm long, and in- 

 gestive attempts ranged from 23 to 44/session. 

 Cynoscion regalis exhibited frequent investiga- 

 tive responses (Table 3) which, unlike those of 

 most of the other fish, usually involved direct con- 

 tact with the worm by bumping it with its snout. In 

 some cases following this contact, the fish would 

 show a headshaking reaction similar to that pro- 

 duced by attempted ingestion. Cynoscion regalis 

 consumed Scoloplos fragilis during the first trials 

 of the control series (Table 4). 



During the course of these experiments, indi- 

 viduals of each species offish were given the op- 

 portunity to feed on several other species of 

 polychaetes. These included Spio filicornis, Neph- 

 tys incisa. Nereis virens. Glycera americana, 

 Scolecolepides viridis. and- Hydroides dianthus. 

 Each fish readily consumed each of these species 

 from several size classes, in almost every case on 

 the first attempt. 



Preliminary data has also been collected on 

 Eumida sanguinea tested with L. maculata. Test 

 worms ranged from 9 to 13 mm long and were 

 consistently rejected. A 69 mm L. maculata re- 

 jected a 13 mm long E. sanguinea 20 times over a 

 single session, while a 91 mm flounder rejected a 

 12 mm long worm 38 times in a session. Investiga- 

 tions ranged from 6 to 10/session and showed no 

 obvious relationship with ingestive attempts. In 

 qualitative observations, it was also noted that the 

 rock gunnel rejected both P. mucosa and P. 

 maculata. 



Removal of the mucus coat from P. mucosa re- 

 sulted in quick consumption by P hoi is gunnellus. 

 Emplacement of the phyllodocid mucus on a small 

 Nephyts incisa, which were previously a quick 

 meal for P. gunnellus. resulted in rejection of the 

 nephtyd polychaete by the rock gunnel many 

 times prior to ingestion. 



Initial observations were also made on the sea 

 robin, Prionotus evolans. fed Stylochus zebra. 

 Lineus ruber, and Phascoleopsis gouldi. Fundulus 

 heteroclitus and C. regalis were also tested with P. 

 gouldi. In each case the fish showed adverse reac- 

 tions (coughing, headshaking, and rejection) after 

 ingestive attempts. The sea robin rejected S. zehi-a 

 75 times over eight trials before consuming the 

 flatworm. In many cases, the turbellarian was 

 held in the buccal chamber for as long as 21 s 

 before ejection. Both the nemertean and the flat- 

 worm produced copius quantities of mucus when 

 irritated, whereas the sipunculid did not. 



Behavior of Phyllodoce mucosa 



Phyllodoce mucosa showed relatively consistent 

 reactions upon release into the aquarium and fol- 

 lowing rejection. When first released, the worm 

 fell slowly through the water in a semicurl posi- 

 tion, or curled in a tight ball and fell at a slightly 

 faster rate. After a worm was taken and rejected 

 by a fish, it was covered with a thick layer of 

 viscous mucus. Immediately after rejection, the 

 worm coiled into the tight, spheroid position. In 

 this position, it was either retaken by the fish and 

 the process repeated until the worm was eaten, or 

 the worm was dropped, after initial attempts, to 

 the floor of the tank. If the worm drifted unharmed 

 to the floor of the aquarium, it usually started 

 what appeared to be an exploratory phase which 

 consisted of several short excursions in various 

 directions before setting out on a single, straight 

 path toward one of the corners of the aquarium. 

 During this exploratory period, the worm held its 

 dorsal parapodial cirri folded against its dorsum. 



Histology and Ultrastructure of 

 Phyllodoce mucosa Parapodial Cirri 



The glandular and sensitive dorsal and ventral 

 parapodial cirri of P. mucosa are the primary 

 sources of externally released mucoid secretion. 



The dorsal cirrus possesses a large nerve which 

 runs along the cirral axis and then radiates cen- 

 trally into several smaller nerves which wind be- 

 tween the large cirral mucocytes (Figure 1). 

 Numerous free neural extensions penetrate the 

 cirral epithelium. Large, ovoid mucocytes, which 

 stain beta-metachromatically with toluidine blue 

 (Figure 1, lower), fill most of the cirrus. These 

 broad and elongated cells have small basal nuclei. 

 In worms that have been irritated prior to fixation, 

 the previously metachromatic mucocytes appear 

 as large, empty vacuoles surrounded by many 

 immature mucus cells (Figure 1, upper). The lat- 

 ter are usually small, irregularly shaped cells 

 which are densely packed with basophilic but or- 

 thochromatic secretory granules. The outer, cen- 

 tral portion of the dorsal cirrus has a narrow bank 

 of melanic pigment cells. There are also thin mus- 

 cle bands which enter the cirrus along the dorsal 

 region of the cirral peduncle. 



Electron microscopy reveals a dense microvillar 

 and ciliary border lining the short, columnar 

 epithelium of the dorsal cirrus (Figure 2). The 

 epithelial cells have large, irregular nuclei with 



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