FISHERY BULLETIN: VOL. 74, NO. 2 



tail so that the caudal fin was alongside the head. 

 From 13 November to 20 December 1968, obser- 

 vations were made on the position offish attached 

 to four hinged sea scallop shells or "clappers." 

 These were positioned on the bottom of an 

 aquarium, with one of each of these pairs placed 

 with the right valve (flat valve) up and the left 

 valve down. One value rested on the bottom and 

 the other was at an angle of approximately 30°- 

 40°. Of 40 observations, 957c of the fish in shells 

 were attached upside-down to the top valve of the 

 clapper with as many as eight attached to the 

 same valve. The inverted resting position was 

 also the most commonly observed during the re- 

 mainder of the time fish were maintained in the 

 laboratory. 



Feeding 



Liparis inquilinus has several morphological 

 and behavioral adaptations which may allow it to 

 feed at night. In aquaria, fish swimming over the 

 bottom appeared to depend on reception of tactile 

 and/or gustatory stimuli received by the head and 

 pectoral fins. Swimming resulted from the com- 

 bined action of the tail and the upper lobe of the 

 pectoral fins. The eight or nine filaments in the 

 lower lobe of the pectoral fins were extended ver- 

 tically toward and often touched the bottom. 

 When amphipods were placed in aquaria, fish did 

 not appear to respond to visual cues but feeding 

 usually occurred when the head or the lower lobe 

 of the pectoral fin touched an amphipod. If food 

 touched the head, it was immediately ingested. If 

 food touched the pectoral fin, the fish quickly 

 backed up or arched its body to the side and 

 sucked in the prey. The rays in the lower lobe of 

 the pectoral fin of L. inquilinus contain dark 

 staining buds along the surface of each ray (Fig- 

 ure 5A) which are most abundant at the tips 

 (Figure 5B). They are identified as taste buds 

 on the basis of their similarity to the figures 

 presented by Bardach and Case (1965). They 

 described the sensitivity of the pelvic fins in 

 Urophycis chuss and the pectoral fins in Pri- 

 onotus carolinus and P. evolans to gustatory 

 stimuli. Freihofer (1963) suggested that the par- 

 ticular pattern of the ramus lateralis accessorius 

 nerve to the pectoral and pelvic fins in the Li- 

 paridae allows the development of these fins as 

 "sensory, locomotor and support appendages." 

 The well-developed cephalic lateralis system of L. 

 inquilinus may also function in detecting moving 



prey. Occasionally fish sucked in amphipods 

 which passed within less than 1 inch of the head. 

 Liparis inquilinus feeds on benthic prey. 

 Stomachs of fish collected in nature contain al- 

 most exclusively small crustaceans and small 

 numbers of sand grains. In the laboratory, sand 

 from the bottom was frequently sucked in with 

 food items and then discharged from the gill 

 opening. A round mouth, as in L. inquilinus, is 

 well-adapted to sucking in prey (Alexander 1967). 



Behavior of Fish Associated 

 with Sea Scallops 



The association between L. inquilinus and sea 

 scallops is well-developed and both partners show 

 definite behavioral adaptations. Fish collected 

 from sea scallops were isolated from them for sev- 

 eral weeks. Upon reintroduction of fish into 

 aquaria containing acclimated sea scallops, many 

 of the fish swam around and over the scallops but 

 concentrated most of their activity along the scal- 

 lops' mantles. Most fish alternated between 

 swimming parallel to the mantle with the lower 

 lobe of the pectoral fin extended toward it or 

 swimming with the head oriented directly toward 

 the mantle. The tentacles on the mantle often 

 contracted but the valves did not close. On one 

 occasion a fish "mouthed" a tentacle, an action 

 similar to the acclimitization behavior of some 

 pomacentrid fishes associated with anemones 

 (Mariscal 1966). On two occasions, fish attached 

 to the mantle, and in one of these instances the 

 tentacles of the scallop mantle moved over the 

 body of the fish and depressed the anterior por- 

 tion of the dorsal fin. There was no reaction by 

 either partner and eventually the fish attempted 

 unsuccessfully to enter the scallop. 



The tentacles of the sea scallop are tactile and 

 chemical receptors (Bourne 1964) and may be 

 able to discriminate between L. inquilinus and 

 other fishes. In aquaria, sea scallops exposed to 

 individuals of Gobiosoma bosci and Gobiesox 

 strumosus reacted negatively, when the mantle of 

 the scallop was brushed by either species, by clos- 

 ing the valves. Similar results were observed 

 when Fundulus heteroclitus and Tautogolabrus 

 adspersus, were exposed to sea scallops (Musick 

 1969). 



Liparis inquilinus occasionally may enter an 

 alternate host species. Hoff (1968) reported a 

 specimen of L. atlanticus from the bay scallop, 

 Aequipecten irradians, in Buzzards Bay, Mass. 



414 



