C. G. Bookhout

THE LARVAL DEVELOPMENT OF CALLINECTES SAPIDUS RATHBUN REARED IN THE LABORATORY

The crabs which comprise the family Portunidae include several commercially important species and studies on their life history have been in progress for the last 100 years. Of the British species only Portunus puber (L.) has been successfully reared in the laboratory through all larval stages to the first crab (Lebour, 1928). Larvae of Carcinus maenas Penn. have been described by a variety of workers but the complete development is not known from laboratory rearing. Of the American species Callinectes sapidus Rathbun is the most important commercial crab in the Western Atlantic and Gulf of Mexico. Churchill (1942) described the larval development of C. sapidus by reconstructing the sequence of stages from planktonic material. Hopkins (1943, 1944), rearing the larvae through the third zoeal stage, found that not all of the stages fit the description given by Churchill (1942) and was of the opinion that the larvae described by Churchill (1942) represented several different species. The complete larval development of C. sapidus, from hatching to the first crab stage and beyond, was first reported from laboratory rearing by Costlow, Rees and Bookhout (1959). While a brief account is given of the number of stages, the duration of the intermolt periods, and the time required for complete development, the larval stages are not described nor is detailed information given on the various environmental factors under which complete development occurred. The present study has had two major objectives: one, to provide a detailed description of all the larval stages of Callinectes sapidus Rathbun reared in the laboratory; and two, to determine the effects of salinity and temperature on larval development. METHODS

Studies on the Larval Development of the Crab, Rhithropanopeus harrisii (Gould). I. The Effect of Salinity and Temperature on Larval Development

AT THE present time the Xanthid crab, Rhithropanopeus harrisii (Gould), is widely distributed in brackish water and estuarine conditions throughout the Western world. The normal geographical distribution of the species, however, was probably limited to the low-salinity waters emptying into the western Atlantic and the Gulf of Mexico. Rodriguez (1963) reported it from Lake Maracaibo, Venezuela, and Wurtz and Roback (1955) found it in rivers emptying into the Gulf of Mexico in salinities from 0.006 to 22.6 p.p.t. On the east coast of North America, Pinschmidt (unpublished data, 1963) collected adults in the Newport River, North Carolina, in salinities from 0.5 to 25 p.p.t.; Ryan (1956) found the crabs in the Chesapeake Bay in salinities from 2.8 to 18.6 p.p.t.; and Bousfield (1955) collected the zoeal larvae in the Miramichi Estuary, Canada, in salinities from 4 to 23.5 p.p.t.

Salinity-Temperature Effects on the Larval Development of the Crab, Panopeus herbstii Milne-Edwards, Reared in the Laboratory

LITT LE is known of the influence of physical factors on the complete larval development of Xanthid crabs. In reports on the successful rearing of the larvae in the laboratory, data on salinity and temperature are either omitted (Hart, 1935; Knudsen, 1958) or, when given, are limited in range (Chamberlain, 1957). Connolly (1925) mentions that the larvae of Rhithropanopeus harrisi were obtained from waters of different salinity but does not give the hydrographic data for the collecting stations. Bousfield (1955), concerned primarily with distribution of barnacle nauplii in the Miramichi Estuary, does indicate the range of salinity in which he found adults and zoeae of R. harrisi. Studies on the development of the Xanthidae have been primarily confined to descriptions of larval stages based on reconstructions from the plankton (Birge, 1883, Neopanope texana sayi; Hyman, 1925, N. texana sayi, Panopeus herbstii, Eurypanopeus depressus and a few stages of other Xanthids; Connolly, 1925, R. harrisi). More recently the larvae of some species of this family have been reared successfully in the laboratory (Hart, 1935, Lophopanopeus bellus; Chamberlain, 1957, N. texana sayi; Knudsen, 1958, 1959a, 1959b, L. leucomanus leucomanus, L. bellus diegensis, Paraxanthias taylori; and Costlow and Bookhout, 1961a, E. depressus, and 1961b, P. herbstii).

THE COMPLETE LARVAL DEVELOPMENT OF SESARMA CINEREUM (BOSC) REARED IN THE LABORATORY

Numerous incomplete descriptions exist of larval development of the Grapsidae l)ut they are usually based on reconstructions from planktonic material or confined to the first zoeal stage obtained from hatching in the laboratory. Cano (1891) described the development of Pachygrapsus marmoratus up to the crab stage but Hyman (1924) questioned the staging of the three zoeal stages by Cano (1891) and describes 5 zoeal stages from material collected at Beaufort, N. C. Conn (1884), comparing portions of larvae of Brachyura and Macrura, includes some appendages and the telson of Sesarma before and after hatching. Hyman (1924) gave a description of the first zoeae and appendages of Sesarma reticulata and, in describing the first stage of S. cinereum, noted that the two species are very similar morphologically. Aikawa (1929) described the first zoeae of Sesarma sp. l)riefly and figured the first stage of S. picta (1937), comparing setation of some append ages with the description given by Hyman. Thus only the first zoeal stage of any species of Sesarma has been described. The purpose of the present study has been to rear the larvae of Sesarma cinereum (Bosc) in the laboratory, from hatching to the first crab stage, and provide a description of all larval stages.

LARVAL DEVELOPMENT OF BALANUS AMPHITRITE VAR. DENTICULATA BROCH REARED IN THE LABORATORY

While there have been numerous studies on Cirripedia larvae based on reconstructed life-histories, to date there have been only three reports on nauplii reared from the egg through all larval stages to the sessile form, that of Herz (1933) for Balanus crenatus, Hudinaga and Kasahara (1941) for Balanus amphitrite hawaiiensis, and Costlow and Bookhout (1957) for Balanus eburneus. This method has the advantage over reconstructed life-histories in that one can be sure of the identity of the adult, the source of eggs and future larvae. Once the life-histories of all species of barnacles in a given area have been described, ecological studies may be made with a greater degree of assurance. Ecological investigations based on sampling, such as that of Bousfield (1955), may provide the number of stages, the approximate duration and mortality of the individual stages, and the distribution and fluctuations in large populations. Laboratory studies on individually reared larvae, however, can give more detailed information on all phases of the life-history other than distribution and population fluctuations. Both types of research are required before a complete picture can be obtained. Laboratory studies are necessarily prerequisite to physiological and genetic investigations. Balanus amphitrite denticulata Broch is one of the most widely distributed acorn barnacles. It has been reported from the tidal waters of Britain which are artificially heated by industrial effluents (Crisp and Molesworth, 1951), the estuaries of South Africa (Sandison, 1954), and the East and West coasts of North America (Dr. Dora Henry, personal communications). In spite of its world-wide distribution only the first two larval stages have been described (Sandison, 1954). Bishop (1950) believes that Balanus amphitrite denticulata merits a more thorough study and questions its position as a variety of B. amphitrite. Thus it should be of interest to compare the larval development of this variety with the descriptions of larvae of Balinus amphitrite albicostatus (Ishida and Yasugi, 1937) and Balanus amphitrite hawaiiensis (Hudinaga and Kasahara, 1941). Balanus amphitrite denticulata is the most abundant fouling organism in the inter-tidal region at Beaufort, North Carolina and breeds during the same summer months as Balanus eburneus. During the past two years we have followed the larval development of B. amphitrite denticulata in the laboratory to determine the number of stages, the frequency of molting, and the duration of the intermolt periods. Our secondary objectives were to compare the appendage setation and body form with the corresponding naupliar stages of the other two varieties of Balanus amphitrite which have been described and with the larvae of barnacles belonging to different species and genera.

LARVAL DEVELOPMENT OF BALANUS EBURNEUS IN THE LABORATORY

A technique has been devised for rearing segregated barnacle nauplii, under controlled laboratory conditions, which permits daily observations on the frequency of molting, the number of stages, and the specific characteristics of each stage. From a study of 121 segregated Balanus eburneus, plus hundreds in mass culture, reared on Chlamydomonas sp. and Arbacia larvae at 26° C. the following conclusions may be drawn:1. Ecdyses provide a definitive method for staging nauplii. The larval phase of B. eburneus consists of six naupliar stages and one cyprid stage. Secondary criteria, such as body size, spine structure, and appendage setation, are given for the larval stages.2. The duration of the six naupliar stages is as follows: first stage, 15 minutes to 4 hours; second stage, one to two days with an average of one day; third stage, one to four days with an average of 1.5 days; fourth stage, one to four days with an average of two days; fifth stage, one to five days with an average of 2.6 days; and the sixth ...

MOULTING AND GROWTH IN BALANUS IMPROVISUS

The Cirripedia differ from other arthropods in that the body is enclosed by calcareous plates which are not shed with the chitinous layers of the animal body and the inner lining of the mantle. As early as 1854 Darwin reported that members of the families Balanidae and Chthamalidae underwent periods of exuviation. He reports that Mr. W. Thompson of Belfast kept twenty specimens of Balanus balanoides alive, presumabLy in the laboratory, and on the twelfth day all had moulted once and one individual twice. The frequency of moulting over an extended period of time has not been determined accurately for any sessile barnacle, presumably because of the difficulties involved in maintaining them in the laboratory. Thomas (1944) reports that moults of a selected group of Balanus perforatus of uniform size but unknown age occurred about every fifth day but makes no reference to the period over which these observations were made. Other than these observations there has been no statement, to our knowledge, concerning the relationship between growth of shell plates and ecdyses nor is the frequency of moulting and the intermoult period, from the time of settling, known for any length of time in any barnacle. The purpose of this investigation was to determine, therefore, a medium which would support growth of barnacles in the laboratory, to ascertain the time of moulting, period of intermoult, and the relationship of shell growth to the moulting cycle. Balanus improvisus Darwin, a barnacle which settles at Beaufort, N. C. during the winter and spring months, was selected for this study.

Molting and Respiration in Balanus amphitrite var. denticulata Broch

FISH, MARIE POLAND. 1954. The character and significance of sound production among fishes of the western North Atlantic. Bull. Bingham Oceanog. Coll., 14:1-109. FISH, MARIE POLAND, KELSEY, A. S., JR., and MOWBRAY, W. H. 1952. Studies on the production of underwater sound by North Atlantic coastal fishes. Jour. Marine Res., 11:180-93. GRIFFIN, DONALD R. 1950. Underwater sounds and the orientation of marine animals: a preliminary survey. Project NR 162-429, O.N.R. and Cornell University, Tech. Rept. No. 3. ATI No. 90329. MOULTON, JAMES M. 1956. Influencing the calling of sea robins (Prionotus spp.) with sound. Biol. Bull., 111:393-98. TAVOLGA, WILLIAM N. 1954. Reproductive behavior in the gobiid fish, Bathygobius soporator. Bull. Amer. Mus. Nat. Hist., 104:427-60.