FEEDING, CLEANING, AND SWIMMING BEHAVIOR IN LARVAL STAGES 

 OF PORCELLANID CRABS (CRUSTACEA: ANOMURA)' 



S. L. Conor and J. J. Conor* 



ABSTRACT 



Pachycheles rtidis, Pachycheles pubescens, Petrolisthes eriomerus, and Petrolisthes 

 cinctipes have a swimming prezoeal stage of short duration. The prezoeal form is prob- 

 ably related to escapement of the larvae from the confined adult habitat. 



Both zoeal stages are strong swimmers, moving both forward and backward by means 

 of the maxillipedal exopodites, aided by the telson. Zoeae have a well-defined cleaning 

 behavioral sequence for removal with the mouth parts of particles from the telson and 

 the maxillipedal endopodites. The two zoeal stages are carnivorous and capture live 

 prey upon contact but do not appear to locate prey visually. Prey are caught with the 

 maxillipedal endopodites and held with the flexed abdomen and telson. 



At the molt to megalopa, the larva becomes a filter-feeding herbivore like the adult. 

 Other adultlike behavior of the megalopa includes use of the fifth legs for cleaning and 

 attempts by older megalopae at swimming by clapping the abdomen. Megalopae filter 

 feed only when suspended algal food is present; water movement enhances feeding but 

 is insuflficient alone to induce feeding. At first, using their abdominal pleopods, megalopae 

 swim continuously, later swim intermittently, and finally settle permanently if a substrate 

 suitable for clinging is available. 



A large amount of information is available about 

 the comparative larval morphology of most 

 groups of decapod Crustacea. Further under- 

 standing of the adaptive significance of larval 

 morphology and its changes during larval life 

 requires comparable information, now largely 

 lacking, about larval behavior and ecology. The 

 present state of knowledge on the larvae of 

 porcellanid crabs is typical in this respect, with 

 a growing descriptive literature available but 

 little known about other aspects of larval biology. 

 A few observations on various features of porcel- 

 lanid larval behavior have been given by Russell 

 (1925), Spooner (1933), Foxon (1934), Gurney 

 (1942), Lebour (1943), Greenwood (1965), and 

 Knight (1966). None of these studies present 

 a complete account of any behavior pattern 



^ This research was supported in part by a trainee- 

 ship from Crant Nos. 5T1-WP-111-02, -03, and -04, 

 Federal Water Quality Administration and by National 

 Oceanic and Atmospheric Administration (maintained 

 by the U.S. Department of Conrmerce) Institutional 

 Sea Crant 2-35187. 



" Department of Oceanography and Marine Science 

 Center, Oregon State University, Newport, OR 97365. 



Manuscript accepted February 1972. 



FISHERY BULLETIN: VOL. 71, NO. 1, 1973. 



throughout development. Information on food 

 and feeding is incomplete and somewhat incon- 

 sistent. The detailed studies on feeding and 

 respiration of adults by Nicol (1932) and Knud- 

 sen (1964) indicate that adult porcellanids are 

 specialized filter feeders. The available infor- 

 mation indicates that zoeae are carnivorous or 

 possibly also detrital feeders. Since it is now 

 known that decapod zoeae are typically strict 

 carnivores capturing live prey, a change in diet 

 and mode of feeding during the development of 

 porcellanids would be expected, but has not been 

 clearly described. 



Large numbers of live larvae of all develop- 

 mental stages and ages were available in lab- 

 oratory cultures during a study of the larval 

 development of four species of porcellanid crabs 

 (Gonor and Gonor, 1973). Several aspects of 

 the behavior of the larvae being cultured were 

 studied closely throughout development. Special 

 attention was given to the ontogeny of normal 

 respiratory, feeding, cleaning, and locomotory 

 behavior patterns from hatching through devel- 

 opment to the first juvenile crab stage. These 



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