An unusual abbreviated larval life in the estuarine burrowing prawn Callianassa kraussi (Crustacea: Decapoda: Thalassinidea)

The larval stages of Callianassa kraussi Stebb. were previously unknown. Larvae were bred out in the laboratory and found to be incapable of swimming. There are two larval stages, lasting 3 to 5 days in sea water of 34 to 35 S at 20 °C. Observations under simulated field conditions in the laboratory, and in the field—where burrow casts were made using a polyester resin, indicated that the larvae metamorphose to the first post-larval stage in the parent burrow, and then burrow directly into the wall of the parent burrow.     

Latitudinal variation in the reproductive biology of the burrowing ghost shrimp Callianassa filholi (Decapoda: Thalassinidea)

Population structure and reproductive ecology of the burrowing ghost shrimp Callianassa filholi Milne-Edwards, 1878 were studied in populations along a latitudinal gradient throughout New Zealand during the breeding season. Size-frequency distributions revealed unimodal populations, with predominantly sexually mature shrimp. All populations showed an unbiased sex-ratio, and there appeared to be no significant difference in size (carapace length, CL) between sexes. At the same time, CL and size at maturity differed significantly between populations; however, a general increase in sizes from north to south was not consistent throughout the latitudinal range studied. The timing of the breeding cycle differed significantly between populations, and breeding started earlier in southern populations. Number of embryos (fecundity) increased linearly with female CL at each location, but rates differed significantly between populations. Embryo size was not related to number of embryos, and the former increased significantly with latitude. With the exception of embryo size, observed differences in body size/size at maturity and reproductive timing between C. filholi populations are thought to be determined by food availability rather than temperature. Thus, further study is suggested on these aspects of thalassinid reproductive biology. Received: 17 June 1999 / Accepted: 8 January 2000     

Respiratory regulation and the role of the blood in the burrowing shrimp Callianassa californiensis (Decapoda: Thalassinidae)

Questions relating to oxygen extraction and hemolymph oxygen transport have been investigated in the burrowing shrimp Callianassa californiensis Dana. The relationship of oxygen consumption to oxygen tension was determined in intermolt and postmolt shrimp. Soft postmolt individuals had higher rates of oxygen consumption and a somewhat lower critical oxygen tension than intermolt specimens. Both oxygen-carrying capacity and hemocyanin content are somewhat lower in postmolt compared to intermolt shrimp. The measured gradient between postbranchial (pericardial sinus) and prebranchial (abdominal sinus) hemolymph oxygen content is small and highly variable, and is not affected by exposure to anoxic stress. Hemolymph pH and buffering capacity are high. The oxygen consumption-oxygen tension relationships and respiratory properties of the hemolymph are discussed in relation to the hypoxic environment associated with the habitat of these crustaceans.Supported in part by Institutional Sea Grant 04-3-158-4 and Public Health Service Grant HL 12326.Communicated by J.S. Pearse, Santa Cruz     

Temperature tolerance of the estuarine prawn Upogebia africana (Anomura,Crustacea)

Continuous temperature measurements were made in a typical South East African estuary. Mean summer (November to March) temperatures were in the range 19° to 24°C, and in winter (June to August) from 13° to 16°C. Large daily temperature fluctuations of 6° to 10°C occurred in summer; these appear to result from tidal movement of cool sea water into the estuary. In winter, temperature fluctuations were much smaller (3° to 5°C). The burrowing prawn Upogebia africana (Obtmann) was found to have an upper lethal temperature of 29°C in both winter and summer. The resistance time of prawns to temperatures above 30°C was much greater in summer than in winter. It was possible to acclimate winter prawns and increase their resistance time to a level comparable to that of summer individuals. A latent period of 40 h occurred before acclimation effects were detectable. Long-term exposure of prawns to high temperatures did not increase their resistance above that of summer prawns. Water at a temperature above this upper lethal temperature is not pumped through the burrows. This avoidance behaviour considerably increases the ability of U. africana to withstand short-lived temperature extremes.     

Microbial activity and accumulation of organic matter in the burrow of the mud shrimp, <Emphasis Type="Italic">Upogebia major</Emphasis> (Crustacea: Thalassinidea)

Microbial activity and accumulation of organic matter in the burrow of the thalassinidean mud shrimp, Upogebia major, were studied on a tidal flat along the northern coast of Tokyo Bay, Japan. The burrow of U. major is Y-shaped with an upper U-shaped part plus a lower I-shaped part. Its lower part can extend to a depth of 2 m. In the present study, we compare electron transport system activity (ETSA), bacterial abundance and organic matter content [total organic carbon (TOC), total nitrogen (TN) and chlorophyll a (chl. a)] of the burrow wall sediment with the tidal flat surface and non-burrow sediments. We also compared the U- and I-shaped part in terms of these parameters. ETSA in the burrow wall was higher than at the tidal flat surface in the warmer season, and was always higher than at surrounding non-burrow sediments. Bacterial abundance in the burrow wall was higher than at the tidal flat surface and surrounding sediment. TOC and TN contents in the burrow wall were two to three times higher than those at the tidal flat surface and non-burrow sediments, regardless of season. However, there was no significant difference in chl. a content between burrow wall and tidal flat surface. These results suggest that organic enrichment of the burrow wall is a result of organic matter particles such as phytodebris accumulation along the burrow wall. For all parameters of the burrow walls, no statistical differences were found between the two parts. Present results indicate that U. major actively transports the water containing suspended organic particles not only through the U-part but also into the deeper I-part. These indicate that burrow of the mud shrimp provides a dynamic environment for microbial community in tidal flat sediment.     

Comparison of gut morphology and gut microflora of seven species of mud shrimp (Crustacea: Decapoda: Thalassinidea)

The gut morphology is described for seven species of Thalassinidea; Callianassasubterranea (Montagu), Jaxea nocturna Nardo, Axius stirhynchus Leach, Calocaris macandreae Bell, Upogebia pusilla (Petagna), U. deltaura (Leach) and U. stellata (Montagu). Differences were observed in the structure of the dorsal and lateral teeth of the gastric mill. Callianassa subterranea and A. stirhynchus had simple robust dorsal teeth and proportionally larger lateral teeth with flexible spines. The three upogebiids had complex dorsal teeth that were highly ridged and proportionally smaller lateral teeth with inflexible spines. The dorsal and lateral teeth of J. nocturna were intermediate in form. The dorsal tooth of Calocaris macandreae, although relatively simple in design, possessed accessory projections, or “wings”, on either side of the main structure. The lateral teeth were proportionally quite large, but lacked ridges and spines. The epithelia surfaces of the digestive gland, midgut and posterior diverticulum were similar for all seven species. Differences were observed in the morphology of the hindgut. The hindgut lining was completely smooth for the three upogebiid species. The other thalassinidean species had four distinct rows of cuticular projections situated on top of the ridges formed by the longitudinal convolutions of the hindgut. The arrangement of these projections varied between species. A gut flora was observed for six of the seven species, the exception being C. macandreae. The differences observed in the structure of the gut are discussed in relation to feeding and thalassinidean phylogeny. Received: 3 July 1998 / Accepted: 8 October 1998     

Settlement cues in successive developmental stages of the ghost shrimps Callichirus major and C. islagrande (Crustacea: Decapoda: Thalassinidea)

Larvae of Callichirus major (Say) and C. islagrande (Schmitt) were given unconditioned water with sand, water conditioned by previous exposure to adults (AW) without sand, or the combination of both AW and sand to determine if these factors served as settlement cues. Shrimp were first given stimuli upon reaching the last zoeal stage (ZIV), the decapodid stage (D), or the first juvenile stage (J1). Once initiated, exposure of shrimp to stimuli was maintained until termination of␣the experiment. Stage duration, burrowing activity of decapodids and early juveniles and location of exuviae were observed daily. Exposure to sand and AW did not decrease duration of the decapodid stage in either species. However duration of ZIV in C. major appeared to decrease when these stimuli were offered at this stage; this suggests that molting to Stage D may be delayed without such cues. When stimuli were examined separately, AW was found to have a significant effect on the duration of ZIV, while the effect of sand with unconditioned water and effects of simultaneously offered stimuli were not significant. Shrimp that received stimuli at ZIV subsequently burrowed more at D and J1 than individuals that did not receive stimuli at ZIV. Location of exuviae was recorded as on top of sand (not burrowed during molt) or within sand (burrowed during molt) for each shrimp's molt from Stages D to J1 (D molt), and from J1 to J2 (J1 molt). In C. major, the percentage of D exuviae and J1 exuviae found within sand as opposed to on top of sand was significantly higher in individuals which received stimuli at ZIV than for those that first received them at D or J1. When stimuli were examined separately in C. major, the effect of sand on burrowing activity was highly significant, while AW and the stimuli in combination had weaker effects. For C. major, AW appeared to accelerate development to D, while sand triggered settlement. Neither stimulus altered stage duration or burrowing activity of C. islagrande. Received: 7 December 1997 / Accepted: 24 July 1998     

Burrow structure, burrowing and feeding behaviour of Corallianassa longiventris and Pestarella tyrrhena (Crustacea, Thalassinidea, Callianassidae)

The behaviour of the Caribbean Corallianassa longiventris and the Mediterranean Pestarella tyrrhena, two burrowing thalassinideans, was studied in situ and in laboratory aquaria. Burrows of C. longiventris were closed most of the time; they consist of a deep U (down to 1.5 m) with upper and deeper chambers, some of them filled with macrophyte debris. The burrows of P. tyrrhena reached down to a maximum depth of 54 cm and consisted of a shallow U with a mound and a funnel, and a spiral shaft from which several, often debris-filled chambers branched off. The appearance of C. longiventris at the sediment surface to collect debris is strongly triggered by wave swell or odours from plant and animal juices; its burrows are opened within 10 min. The surface activity of P. tyrrhena was relatively less frequent and less predictable. Inside the burrows, both species exhibited different patterns of time allocated to 25 defined behavioural states. After being offered seagrass debris, P. tyrrhena spent relatively less time manipulating this debris, but it handled sediment more often than C. longiventris. During frequent mining events, both species showed sediment-sorting behaviour, which brought a parcel of sediment in close contact with the mouthparts; some of this sediment may be ingested because the fecal rods produced by both shrimps contain very fine sediment particles. Seagrass debris is irregularly tended by P. tyrrhena after its introduction into the chambers. Such material ultimately becomes buried. Corallianassa longiventris frequently returns to its debris chambers to pick up pieces of seagrass, which are subsequently cut with the chelae or ripped with the third maxilliped and then transported to another empty chamber nearby. Pieces become smaller with time and show curved cutting edges and bite marks. After 100 to 140 days, 2 to 6 g(dw) seagrass debris are consumed in this manner by individuals of this species. The debris-related behaviour of P. tyrrhena probably enriches the sediment around the burrow for stochastic encounters during later mining events. Such an indirect benefit may also be effective on a population level because other individuals may also encounter this buried nutrient source. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Facultative lecithotrophy during larval development of the burrowing shrimp Callianassa tyrrhena (Decapoda: Callianassidae)

Survival, developmental and consumption rate (Artemia nauplii ingested per day) as well as predation efficiency (ingested per available Artemia nauplii) were studied during the larval development of the shallow-water burrowing thalassinid Callianassa tyrrhena (Petagna, 1792), which exhibits an abbreviated type of development with only two zoeal stages and a megalopa. The larvae, hatched from berried females from S. Euboikos Bay (Aegean Sea, Greece), were reared at 10 temperature–food density combinations (19 and 24 °C; 0, 2, 4, 8 and 16 Artemia nauplii d⁻¹). Enhanced starvation resistance was evident: 92 and 58% of starved zoeas I molted to zoea II, while metamorphosis to megalopa was achieved by 76 and 42% of the hatched zoeas at 19 and 24 °C, respectively. The duration of both zoeal stages was affected by temperature, food density and their interaction. Nevertheless, starvation showed different effects at the two temperatures: compared to the fed shrimp, the starved zoeae exhibited accelerated development at 19 °C (8.4 d) but delayed metamorphosis at 24 °C (5.9 d). On the other hand, both zoeal stages were able to consume food at an increased rate as food density and temperature increased. Predation efficiency also increased with temperature, but never exceeded 0.6. Facultative lecithotrophy, more pronounced during the first zoeal stage of C.tyrrhena, can be regarded as an adaptation of a species whose larvae can respond physiologically to the different temperature–food density combinations encountered in the wide geographical range of their natural habitat. Received: 28 February 1998 / Accepted: 21 October 1998     

Feeding and digestion in Corophium volutator (Crustacea: Amphipoda)

New observations on the feeding behavior of Corophium volutator, collected from the Menai Strait, Anglesey, UK in 1981, show that detritus drawn into one entrance of the U-shaped burrow is pushed out at the opposing entrance either uningested or as faeces. Periodically, the amphipod turns around in the burrow and recommences feeding, so both the uningested material and the faeces may be reworked by the mouthparts. A feeding individual produces, on average, 16 faecal pellets every 10 min, at a seawater temperature of 18°C. When fed on detritus dyed with azo-carmine, approximately 12 pellets are produced before the foregut, intestine and hindgut are completely clear of previously ingested material and the dye appears in the faeces. Dye which enters the ventral caeca takes between 12 and 48 h to clear this tissue and, furthermore, it is only cleared when the amphipod is feeding. It is concluded that ingested coarse material is subjected only to a primary phase of digestion in the stomach, and that it takes 4 to 24 min to clear the gut. Fine material which enters the ventral caeca is subjected to a secondary phase of digestion and absorption which takes 24 to 48 h. Particles of thorium dioxide and ferritin incorporated in the diet are absorbed by the B- and ageing RF-cells in the ventral caeca. Non-specific esterases occur in the apical regions of the same cells, the mature cells of the anterior dorsal caeca and the cells at the anterior of the intestine. Protease activity is greatest in the lumen of the ventral caeca and the large vacuole of the B-cells. Apart from the lumen of the posterior caeca, there is some protease activity throughout the lumen of the gut. Carbohydrates were localised primarily in the R/F-cells towards the proximal region of the ventral caeca. Lipid was confined to the R/F-cells in the same region.     

Group orientation in Neomysis mirabilis (Mysidacea: Crustacea)

The orientational behaviour of the neritic mysid Neomysis mirabilis in a swarm is considered under natural and experimental conditions. In nature, the swarms exhibit elements of inner integration, such as homogeneous age structure, collective behaviour, and relative constancy of inter-individual spacing. The mysids are guided by combined optomotor and vibrotactile cues, determining their disposition in aquaria of different shapes. Maximum accuracy of spatial arrangement is observed in round vessels. It is suggested that the stress encountered in an aquarium produces responses comparable to those elicited by the presence of a predator. The rigid spatial arrangement at the supra-individual level is interpreted as evolutionally-optimized prey strategy. These elements in the geometrical distribution of individuals in mysid swarms are inherent in other pelagic crustaceans also, and are not controlled by random taxes stimulated by hydrological factors.     

Stranding and matting behaviour in Nyctiphanes australis (Euphausiidae: Crustacea)

Numerous stranding events of the euphausiid Nyctiphanes australis Sars on the coast of south-east Tasmania during the winter months of 1984/1985 are documented. The krill were at a reproductive stage of their life cycle. Strandings almost always occurred on calm, sunny days on beaches with a northerly aspect. Typically, barometric pressure was greater than and wind speed was less than the monthly average. No significant differences were found between stranded euphausiids and those from surface swarms, and the relationship between the two forms of behaviour in this area is discussed. A new form of behaviour termed matting was observed, in which the euphausiids aggregate dorsal-side down on the substrate in shallow water. Matting usually occurs synchronously with stranding. Laboratory experiments showed that N. australis responds to changes in both the plane of polarization and intensity of light with behaviour typical of that observed in stranding and matting events. Light appears to be a key factor mediating these types of behaviour. Hypotheses for the relationship between stranding and matting are offered.     

Neighbor burrow-plugging in Ilyoplax pusillus (Crustacea: Brachyura: Ocypodidae)

The burrow living ocypodid crab Ilyoplax pusillus (De Haan, 1835) sometimes plugs the burrow of neighbors situated from 1.0 to 8.3 cm away with surface mud, while the neighbor, termed the pluggee, is in the burrow. Most pluggers were large males, whereas pluggees were smaller than pluggers and had a sex ratio close to 1:1. After being plugged, most pluggees usually reemerged on the surface within 5 min, but occasionally took up to 77 min to do so. The plugger always foraged or performed waving displays around the burrow of the pluggee while the pluggee stayed inside the burrow. Although the activity site of the pluggee was originally directed toward the burrow of the plugger or the adjacent area, after reemergence its activity site was oriented toward another direction. From these observations, it is suggested that neighbor burrow-plugging is a behavior adopted mainly by large males as a means of maintaining the area of their surface activities against smaller neighbors. My observations were made from June 1984 to June 1985 at Fukuro River Estuary, central Japan.     

Mound building in Ilyoplax pingi (Crustacea: Brachyura: Ocypodidae)

The ocypodid crab Ilyoplax pingi, observed in Kanghwa I., Korea in 1992, builds a mound at the burrow entrance, by piling mud dug out from the burrow. The mounds were made by both waving and non-waving males, and by both ovigerous and non-ovigerous females. The burrow diameter at the widest part tended to be larger in crabs with mounds than in crabs without mounds, whereas the burrow depth was not different between them. The mound density increased in the late exposure period, when the crabs' surface activities declined. Mound removal and rebuilding experiments revealed that the presence of the mounds has the effect of keeping neighboring crabs away.     

Growth and moulting of Neomysis integer (Crustacea: Mysidacea)

The growth and moulting of Neomysis integer (Leach) was investigated in the field and the laboratory. In the Ythan estuary, Aberdeenshire, Scotland, monthly samples taken from November 1976 to October 1978 revealed that the summer generation juveniles and mature individuals grew at a rate of 4 to 5 mm and 1 to 2 mm monthly, respectively. The winter generation had a growth rate of 3 to 4 mm monthly for juveniles and about 1 mm for mature individuals; during the winter there was a period of 3 mo when growth was almost completely stopped. Mysids reared in the laboratory on Artemia sp. nauplii had an average daily growth rate of 0.06 mm at 9°C and 0.09 mm at 16°C. The growth factors of N. integer ranged from 3 to 17% for mature and immature individuals, respectively. Intermoult periods ranged from 3 to 7 d in immature mysids to 12 to 18 d in mature mysids. Average laboratory growth curves calculated from information on growth factors and intermoult periods indicate that at 9°C (winter generation) it takes N. integer 277 d to grow to be a 15 mm mature individual, whereas at 16°C (summer generation) it takes 188 d. N. integer moults 24 times as it grows from a juvenile to a mature individual.     

Comparative studies of carotenoids in the Fauna of the Gullmar fjord (Bohuslän,Sweden). II. Crustacea: Eupagurus bernhardus,Hyas coarctatus and Upogebia deltaura

The carotenoids in the crustaceans Eupagurus bernhardus, Hyas coarctatus and Upogebia deltaura from the Gullmar fjord (Bohuslän, Sweden) were investigated. Their presence was determined by means of columnar and thin-layer chromatography. The following carotenoids were found — in E. bernhardus: ß-carotene, canthaxanthin, lutein epoxy, 4-keto-4-ethoxy-ß-carotene, zeaxanthin, astaxanthin and astacene; in H. coarctatus: cryptoxanthin, 4-keto-4-hydroxy-ß-carotene, lutein (pure and epoxy), astaxanthin, and astacene; in U. deltaura: γ-carotene, canthaxanthin, gazaniaxanthin?, isozeaxanthin, cryptoxanthin, 4-keto-4-hydroxy-ß-carotene, zeaxanthin, astaxanthin and astacene.     

Cellulose digestion and phenol oxidation in coastal isopods (Crustacea: Isopoda)

In order to test three hypotheses on digestive constraints that may have affected the colonization of land by isopods, two marine isopods and one semi-terrestrial species were screened for their ability to oxidize phenolic compounds and digest cellulose in natural and artificial diets. Ligia pallasii (Isopoda: Oniscidea) and Gnorimosphaeroma oregonense (Isopoda: Sphaeromatidea) oxidized dietary phenolics, but Idotea wosnesenskii (Isopoda: Valvifera) did not, even though it feeds on seaweeds that are rich in phenolics. All three species were able to digest some cellulose, but this ability was least developed in the marine phytophagous species, Idotea wosnesenskii, and best developed in the semi-terrestrial L. pallasii. After reducing the number of endosymbiotic bacteria in the hepatopancreas (midgut digestive gland) by feeding antibiotics, cellulose digestion in L. pallasii was significantly reduced. Our results are consistent with the hypotheses that (1) the ability to oxidize phenolics is absent in phytophagous marine isopods, but present in saprophagous marine and semi-terrestrial species, (2) the ability to digest cellulose was an important pre-adaptation facilitating a fully terrestrial life-style in isopods, and (3) endosymbiotic bacteria in the hepatopancreas aid digestion in terrestrial isopods, and to a lesser degree in semi-terrestrial species, but not in marine isopods.     

R-cells and the digestive cycle in Penaeus semisulcatus (Crustacea: Decapoda)

Shrimp, Penaeus semisulcatus, were collected from Kuwaiti waters in 1980, and the R-cells in the hepatopancreas were observed during the digestive cycle. During the first 12 h they absorb soluble material from the lumen of the gland and, subsequently, they take-up soluble and particulate material from the haemolymph. Within the cytoplasm, apical and basal systems of smooth endoplasmic reticulum are concerned with these processes. Pinocytosis only occurs at the basal cell membrane. The absorbed material is stored as lipid and glycogen, and copper, sulphur and other elements are accumulated in a large dense vacuole. These activities are integrated with those of the other cell types to effect the assimilation of food in the hepatopancreas. A scheme is proposed which accounts for the main processes of digestion. The hepatopancreas governs the duration of the digestive cycle, which takes at least 24 h. Observations on the nature of intracellular storage and waste products could be used to assess the dietary requirements of artificially reared shrimp.     

Larval development of Euphausia nana (Crustacea: Euphausiacea)

The larvae of Euphausia nana Brinton in Sagami Bay and Suruga Bay, Central Japan, are described and illustrated. The furcilia stage is separated into six stages on the basis of the form of the pleopods and the number of terminal telson spines. Furcilia I, no pleopod or non-setose pleopods and seven terminal telson spines. Furcilia II, nonsetose and setose pleopods and seven terminal telson spines. Furcilia III, five pairs of setose pleopods and seven terminal telson spines. Furcilia IV, five pairs of setose pleopods and five terminal telson spines. Furcilia V, five pairs of setose pleopods and three terminal telson spines. Furcilia VI, five pairs of setose pleopods and one terminal telson spine. Segmentation of the antennal endopod and mandible palp occurred at the furcilia V stage. The dominant forms of early furcilia larvae of E. nana differed during different seasons of the year. The total lengths of calyptopis III and furcilia I to VI larvae also showed seasonal changes; they were largest in May and smallest from September to December.     

Dominance of larval forms in euphausiid (Crustacea:Eucarida) ontogenesis

Variability and dominance of Euphausia superba Dana larval forms (Furcilia-I and Furcilia-II stages) in the plankton of the Scotia and Weddell Seas have been investigated. New forms (1, 2, 3 and 14) have been recorded. The dominant forms of Furcilia-I stage are proposed to represent the initial dominants. In accordance with the initial dominance, five types of larval form combinations have been established. During the initial dominance change — from 5 to 2, the larval form number increases. This phenomenon is due to parallel development of euphauiid larvae; it results from a developmental pathway change in the main larval mass. Such deviations are reflected in an initial dominance change. In each pathway, the larvae pass through an unequal number of moults before reaching Form 5 (in accordance with the proposed moult scheme of Furcilia-I stage larvae). In the case of initial dominance of less-developed forms, the presence of different parallel pathways increases. As a result, the total number of larval forms present in the plankton changes, causing increased variability of the total number of larval forms. Each type of larval form combination is the result of summation of all larval forms, which derive from different developmental pathways of the larvae in different localities. The most usual developmental pathway for Euphausia superba is through Form 5, which may, thus, be regarded as the main developmental pathway for this species. This pathway probably corresponds to optimal environment conditions for larval growth and morphogenesis with maximal synchronisation of both processes. Consequently, it may be suggested that changes in developmental pathways of larvae are connected with suboptimal environmental conditions.