The feeding apparatus of the Paralithodes camtschaticus, P. brevipes and P. platypus during the transition zoea, glaucothoe and first juvenile stages were analyzed. The mandibles of zoeal larvae are well adapted for grinding of food. The mandibles of the glaucothoe are uncalcified and rudimentary, and the mandibular lateral lobes are apparently incapable of giving support to the masticatory move ment. The setae of endopods and endites of the maxillae and endopods of the first and second maxil lipeds are substituted for minute setae or denticles. The third maxilliped appear to be apparently devel oped, but the crista dentata on the ischium is still not formed. The first juvenile has well calcified mandi ble. The crista dentata on the third maxilliped is completely formed. The setose zoeal foregut has two chambers distinctively separated by a heavily setose cardiopyloric valve. The pyloric stomach has a well developed filter press. The glaucothoe has the foregut chambers and the cardiac pyloric valve unarmed or with few small setae present. The gastric mill and lateral teeth appear for the first time in the juvenile foregut. These observations indicate changing in the feeding of lithodids, in which they abstain from feeding during the glaucothoe stage.

The appropriate feeding regime for larvae and post-larvae of crustacean decapods is essential for successful larval culture. Reports on the development and morphology of the mouthparts and foregut of these crustaceans have aided in the selection of appropriate larval foodstuffs and consequently increased larval survival and growth rate during development. In the present study, the functional morphology of foregut and mouthparts was investigated in larvae and post-larvae of the freshwater prawn M. amazonicum (Heller, 1862). From observations gathered on both the outer and inner feeding apparati the first stage larvae have obligatory lecithotrophy and feeding behaviour is initiated after molting to the second stage. The foregut of the larvae undergoes diverse morphological changes during larval development and the larval foregut of this species is primarily a mixing organ due to the absence of gastric mills and similar structures. After metamorphosis into post-larvae, drastic morphological changes occur in the foregut and mouthparts to adapt the animals to feed on the greater diversity of foods that are available in their new benthic habitat

ABSTRACT. The gross morphology of foregut was investigated and described in detail for four freshwater crab species: a pseudothelphusid, Fredius reflexifrons (Ortmann, 1897) and three trichodactylids -Sylviocarcinus pictus (H. MilneEdwards, 1853), Valdivia serrata White, 1847, and Dilocarcinus septemdentatus (Herbst, 1783). In general, the gastric mills of freshwater crabs showed a similar degree of complexity in relation to other marine species of Anomura and Brachyura previously described in the literature. However, significant morphological differences were observed among the analyzed species, as in ossicle numbers, features and connection types. A total of 38 ossicles were described for S. pictus and V. serrata and 37 ossicles for D. septemdentatus and F. reflexifrons, respectively. The latter species can be distinguished from the others by the presence of a wide cardiac sac resembling two sacs. Most of the ossicles were connected through a rigid connection, and few ossicles were fused. The degree of calcification varied little among the studied species. The differences found among the species suggest that the morphological aspects of the foregut may be useful in the identification of similar species.

The present work was carried out to verify the occurrence and distribution of Cymbasoma longispinosum Bourne, 1890 in a tropical Amazon estuary from North Brazil. Samplings were performed bimonthly from July/2003 to July/2004 at two different transects (Muriá and Curuçá rivers) situated along the Curuçá estuary (Pará, North Brazil). Samples were collected during neap tides via gentle (1 to 1.5 knots) 200 μm-mesh net tows from a small boat. Additional subsurface water samples were collected for the determination of environmental parameters. Males and females of Cymbasoma longispinosum were only observed during September and November/2003. The highest number of organisms was found in September/2003 at the Muriá River transect. The presence of C. longispinosum in samples obtained during September and November/2003 could probably be related to the reproductive period of this species in the studied estuary, which is directly related to the dry period in the region. The highest salinity values and the highest number of individuals observed in September/2003 corroborate with the previous assumption, since no C. longispinosum was found during the months comprising the rainy period (January to June).
O presente trabalho foi desenvolvido para verificar a ocorrência e distribuição de Cymbasoma longispinosum Bourne, 1890 em um estuário tropical amazônico da região norte do Brasil. As coletas foram realizadas bimestralmente de julho/2003 a julho/2004 em dois diferentes transectos (rios Muriá e Curuçá) situados ao longo do estuário do Curuçá (Pará, Norte do Brasil). Amostras foram coletadas durante marés de quadratura por intermédio de arrastos com redes de plâncton de 200μm de abertura de malha, através de um pequeno barco a motor (1 a 1,5 knots). Amostras adicionais de água subsuperficial foram coletadas para determinação dos parâmetros ambientais. Machos e fêmeas de C. longispinosum foram observados apenas durante os meses de setembro e novembro/2003. O maior número de organismos foi encontrado em setembro/2003, no transecto do rio Muriá. A presença de C. longispinosum nas amostras obtidas durante setembro e novembro/2003 poderia estar provavelmente relacionada ao período reprodutivo desta espécie no estuário estudado, o qual está diretamente relacionado ao período seco na região. Os mais elevados valores de salinidade, bem como os elevados números de indivíduos observados no mês de setembro/2003 confirmam a suposição anterior, visto que nenhum indivíduo de C. longispinosum foi registrado durante os meses que incluem o período chuvoso (janeiro a junho)

The complete larval development of the ghost shrimp Lepidophthalmus siriboia Felder & Rodrigues, 1993 was described and illustrated in detail from specimens reared in the laboratory. Ovigerous females were collected at Canela Island in the northeastern region of the State of Pará. The larvae hatch as a prezoea, in which they persist for less than 3 hours. The larval development consists of three zoeal stages and a megalopa. The zoeal development averaged from 69 to 111 hours. The period in the megalopa stage was about 185 hours (about 8 days). The percentage of individuals succeeding in molt into juvenile stage was 91,8%. The first juvenile stage was reached 254 hours (about 10 days) after hatching. Morphological comparisons and their relationship with larvae of congeneric species are briefly discussed.

The development of the foregut structure and the digestive function of the decapods Litopenaeus vannamei, Sesarma rectum and Callichirus major larvae and post larvae were examined. The protozoeal foregut of L. vannamei is simple, lacking a cardiopyloric valve and bearing a rudimentary filter press. In mysis, the filter press is more developed. In the juvenile stage, grooves and a small lateral tooth arise. In S. rectum, the foregut has a functional cardiopyloric valve and a filter press. The megalopal and juvenile stages of this species have a gastric mill similar to those in adult crabs. In C. major, the foregut of the zoeae is specialized, with the appearance of some rigid structures, but no gastric mill was found. Calcified structures are observed in the megalopae and they become more developed in the juvenile stage. The results support suppositions, previously reported in other studies, that feeding behavior of each larval and postlarval stage is directly related to the morphological characteristics of the foreguts.Keywords: foregut, Litopenaeus vannamei, Sesarma rectum, Callichirus major, morphology. Desenvolvimento e morfologia funcional dos estômagos de larvas e pós-larvas de três crustáceos decápodesResumo O desenvolvimento da estrutura do estômago e da função digestiva foi examinada em larvas e pós-larvas de Litopenaeus vannamei, Sesarma rectum e Callichirus major. O estômago do protozoea de L. vannamei é muito simples, sem válvu-la cárdiopilórica e apresenta um filtro pilórico rudimentar. Em mysis, o filtro pilórico parece ser mais desenvolvido. No juvenil I surgem calhas e dentes laterais pouco desenvolvidos. Os estômagos dos zoeae de S. rectum possuem a válvula cárdiopilórica e o filtro pilórico funcionais. Nos estágios megalopa e juvenil I o moinho gástrico é complexo. Em C. major, os estômagos dos zoeae se mostram especializados exibindo algumas estruturas rígidas, mas não apresentam moinho gástrico. Esta estrutura surge no megalopa e juvenil I. Os resultados suportam suposições anteriores que o comportamento alimentar de larvas e pós-larvas está diretamente relacionado com as características morfológicas dos estômagos.

In this study, the gross morphology of the mouthparts and foregut of the ghost shrimp Lepidophthalmus siriboia were investigated from larvae and postlarvae reared in the laboratory. The mouthparts (maxillae and maxillipeds) of the zoeae have a reduced number of setae and spines (or is absent in some individuals), and the foregut, under developed, have few minute setae in the cardiac and pyloric chambers. In contrast, after the metamorphosis into megalopa stage, all feeding appendages have many setae and, the foregut shows a well-developed gastric mill with strong lateral teeth. In the juvenile stage occurs an increase of setae and spines in the mouthparts and the foregut becomes more specialized. These observations strongly suggest that a lecithotrophic development occurs during all zoeal stages but the megalopa and juvenile stages are feeding animals. The functional morphology of the feeding structures of L. siriboia and other decapods will be briefly discussed. KEYWORDSCallianassidae, Lepidophthalmus siriboia, mouthparts, foregut, morphology. Morfologia funcional dos apêndices bucais e do estômago de larvas e pós-larvas de Lepidophthalmus siriboia

Little alteration occurs in the midgut and hindgut during all zoea and in the early glaucothoe of Paralithodes camtschaticus. The gross morphology of the midgut gland is relatively simple. It is com posed of one main and two secondary lobes. The anterior midgut caeca are present in the zoea and early glaucothoe, having histological characteristics similar to those found in the cells of the midgut gland lobes. On the contrary, the posterior caecum differentiated in the midgut of glaucothoe near the time of molting to the first juvenile. Large lipid droplets are accumulated during the zoeal instars in the medial portion of the midgut gland and anterior midgut caeca. A drastic change is observed in all digestive sys tems of the late phase of glaucothoe. The midgut maximally elongates and the anterior midgut caeca lar gely reduce. The posterior lobe elongates, extending up to the second and third abdominal segments. Most cells of the midgut gland of late glaucothoe decrease the previous lipid droplets observed during the zoeal instars, It is proposed that these large amounts of lipids are used as an energy source during the non-feeding glaucothoe stage. The red king crab Paralithodes camtschaticus is one of the most valuable crustacean species in the North Pacific Ocean.1) Researches have been carried out in the wild2) on biological aspects for fisheries and in the laboratory for cul ture purposes.3,4) Despite these undertakings, the character istics of the morphology and function of the digestive system have not yet been clarified in relation to the develop mental stages of zoea, glaucothoe and juveniles.Culture experiments demonstrated no difference of the glaucothoe stage in survival rate and intermolt period be tween feeding and non-feeding.*1 The feeding apparatus and digestive system are considered to develop morphologi cally and functionally during the larval and postlarval stages of king crab. We recently found that a drastic change occurred in the mouthparts and foregut of the glau cothoe after metamorphosis of king crab P. camtschati cus, P. brevipes and P. platypus.*2 These changes strongly suggest that the glaucothoe is a non-feeding stage. The midgut, midgut gland (=hepatopancreas), anterior and posterior midgut caeca, and hindgut are also considered to undergo changes in both morphology and function during the larval and postlarval stages of king crab.The midgut gland of adult crustaceans has been the sub ject of many studies.'-"' The morphology and function of the midgut gland during larval development has been ex tensively reported for lobster Homarus americanus13-15) and for shrimp Penaeus japonicus.16,17) The function and cytology of the midgut gland have been described for the phyllosomas of the spiny lobster and slipper.18) Recently, the developmental changes and the structural mechanism of the midgut gland during the transition forms were inves tigated for the puerulus and postpuerulus of rock lobster Jasus edwardsii.19) On the other hand, no studies have been carried out for king crab larvae, g...