Tube building by the amphipods Lembos websteri Bate and Corophium bonnellii Milne Edwards

Lembos websteri Bate and Corophium bonnellii Milne Edwards are tubicolous. The morphology of tubes collected from Laminaria holdfasts is described and contrasted with that of tubes built amongst filamentous algae in a wave-sheltered environment. In both species tube length is a function of animal length. Corophium build tubes with openings raised above the substratum more commonly than Lembos, and will construct mats of tubes away from solid surfaces; Lembos tend to build against solid surfaces. Tube construction appears to depend upon the ‘knitting’ activity of the first two pairs of peraeopods, utilizing a secretion containing acid and sulphated mucopolysaccharides. The process of tube construction on substrata of known granulometry and the morphology of tubes built in the laboratory are described. The burrowing capabilities of both species are compared. On sand, Lembos tend to build on the sediment surface, whilst Corophium tend to burrow into the substratum. Corophium begin tube building after transference to a new situation much sooner than Lembos, with female Lembos starting to build sooner than male Lembos, Corophium can build a covering tube in < 15 min. In the absence of extraneous material, both species line glass tubes with a meshwork of mucoid filaments. In empty dishes, mucoid tubes are rarely built. The ability of Lembos to colonize wave-exposed sites may be related to its preference for more sheltered spaces within kelp holdfasts.     

Tube-emergence behaviour in the amphipods Lembos websteri Bate and Corophium bonnellii Milne Edwards

The complete emergence from their tubes of the amphipods Lembos websteri Bate and Corophium bonnellii Milne Edwards has been the subject of laboratory investigation in Scotland. Few animals left their tubes during the day. Nocturnal emergence was clearly more frequent, but only in male Lembos websteri was it at all common. Both emergence onto the outer surfaces of Latninaria holdfasts (within which tubes are constructed) and swimming were rarely observed in this species and may be regarded as adaptations to life in wave-exposed habitats. Experimental evidence is presented which suggests that male L. websteri vacate their tubes at night to seek a new female partner. The seemingly parthenogenetic species Corophium bonnellii has no such tube-emergence requirement to facilitate reproduction.     

The feeding habits of the amphipods Lembos websteri Bate and Corophium bonnellii Milne Edwards

The gut contents of both Lembos websteri Bate and Corophium bonnellii Milne Edwards include detritus and sand grains. Lembos websteri collected from Laminaria holdfasts also contain strands of filamentous algae although Corophium bonnellii do not. In addition, macroalgal fragments and naviculoid diatoms are present, more often in Lembos websteri than in the guts of Corophium bonnellii. Occasionally, in animals collected from a sheltered algal turf, arthropod appendages may also be observed in the gut of Lembos websteri. The size of particles consumed by Lembos websteri is larger than in Corophium bonnellii. Feeding in both species is primarily by filtration but a variety of other methods may be used, including deposit-feeding, consumption of food of animal origin (including the species' own eggs), and consumption of tube material. These alternative techniques are brought to bear increasingly in poor feeding conditions. The behavioural sequences involved in these activities are described in detail and food preferenda related to the nutritional state of the animals. Defaecation in Lembos websteri (males and females) is normally followed by immediate refection of the faecal pellet but again is more noticeable when food is scarce. Gut-residence time in both species is ≈ 2 h at 13–15 °C. The proposition is made that Corophium bonnellii is a more efficient small-particle filter-feeder thanLembos websteri and that as such, it has met no evolutionary requirement to recycle its faeces (large particles) in the manner of L. websteri.Lembos, on the other hand, having a very “plastic” feeding repertoire appears to be better adapted to withstand periods of low food availability. The larger particles on which L. websteri feeds will be scarcer and will require more turbulence to keep them in suspension and even at exposed localities where L.websteri is more common, periods of calm occur, so flexibility in food-gathering technique is clearly advantageous. The more efficient small particle filter-feeding technique of Corophium bonnellii is well suited to a life in sheltered waters, where only the smallest particles remain in suspension for long periods, which is so typical of the genus.     

Behaviour of Scrobicularia plana (Da Costa) in water of various salinities

Valve movements, heart and pumping rates have been recorded from Scrobicularia plana (Da Costa) when transferred stepwise from natural sea water to sea water of S = 30% (termed 100%) and then to 80, 60, 40, and 20% sea water, and after direct transfer from 100 to 20% Scrobicularia exhibits short periods of pumping alternating with short ventilatory pauses down to 40% sea water. These are termed activity cycles and contrast with periods of complete quiescence each ≈ 4–12 h long. The heart rate of animals in these salinities is fairly constant during activity cycles. When transferred to 20% sea water, either directly or gradually, short pumping phases alternate with long ventilatory pauses during the initial 72 h. At the same time the heart rate shows wide variation during activity cycles.On transference from 100 to 60% sea water, the valves opened and valve activity pattern returned to normal within 30 min and within 6 h of transfer from 60 into 40% SW. Transfer to 20%, whether stepwise or directly, resulted in valves remaining closed initially for ≈ 10 or 34 h, respectively before opening gradually to expose the mantle margin. The valve adductions were then of reduced frequency and extent.     

Temporal variation in the heart activity of Scrobicularia plana (Da Costa) in constant and tidal conditions

A marked pattern of short-term variation in heart activity is described in Scrobicularia plana (Da Costa). This is unique to Scrobicularia among the bivalves so far investigated. Heart activity, shell movement, and pumping have been recorded during suspension- and deposit-feeding activity and during inactivity. Heart activity in Scrobicularia responds markedly to gross changes in pumping level found during feeding, both heart rate and amplitude, as measured by impedance techniques, increasing rapidly when pumping commences after short periods of cessation. Heart amplitude falls rapidly and heart rate more gradually once pumping ceases. Scrobicularia shows considerable flexibility in behaviour under any given set of conditions. Tidal bradycardia occurs consistently in Scrobicularia only when the water level in the mud falls below the level of the animal in its burrow, pumping activity being maintained if surface water is present.     

Humoral immune response of Galleria mellonella larvae after infection by Beauveria bassiana under optimal and heat-shock conditions

Natural infection of Galleria mellonella larvae with the entomopathogenic fungus Beauveria bassiana led to antifungal, but not antibacterial host response. This was manifested by induction of gallerimycin and galiomicin gene expression and, consequently, the appearance of antifungal activity in the hemolymph of the infected larvae. The activity of lysozyme increased at the beginning of infection and dropped while infection progressed. Exposure of the naturally infected animals to 43 °C for 15 min extended their life time.Galleria mellonella larvae were injected with 10⁴, 10⁵ and 10⁶ fungal blastospores, resulting in the appearance of strong antifungal activity and a significant increase in lysozyme activity in larval hemolymph after 24 h. Antibacterial activity was detectable only when 10⁵ and increased when 10⁶ blastospores were injected. The number of the injected B. bassiana blastospores also determined the survival rate of animals. We found that exposure of the larvae to 38 °C for 30 min before infection extended their life time when 10³ and 10⁴ spores were injected. The increase in the survival rate of the pre-heat-shocked animals may be explained by higher expression of antimicrobial peptides and higher antifungal and lysozyme activities in their hemolymph in comparison to non-heat-shocked animals.     

Genetic data,reproduction season and reproductive strategy data support the existence of biological species in Ophioderma longicauda

Cryptic species are numerous in the marine environment. The brittle star Ophioderma longicauda is composed of six mitochondrial lineages, encompassing brooders, which form a monophyletic group, and broadcasters, from which the brooders are derived. To clarify the species limits within O. longicauda, we compared the reproductive status of the sympatric lineages L1 and L3 (defined after sequencing a portion of the mitochondrial gene COI) during the month of May in Greece. In addition, we genotyped a nuclear marker, intron i51. Each L3 female was brooding, whereas all L1 specimens displayed full gonads, suggesting temporal pre-zygotic isolation between brooders and broadcasters. Statistical differences were found among lineages in morphology and bathymetric distribution. Finally, the intron i51 was polymorphic in L1 (60 individuals), but monomorphic in L3 (109 individuals), confirming the absence of gene flow between brooders and broadcasters. In conclusion, the broadcasting lineage L1 and the brooding lineage L3 are different biological species.     

Female-offspring communication in a Taiwanese tree frog, Chirixalus eiffingeri (Anura: Rhacophoridae)

We assessed the roles of visual and olfactory cues in female-tadpole communication inChirixalus eiffingeri . The mean cumulative time that at least one tadpole was active or begged for food was significantly longer when a female C. eiffingeri was present than when a plastic frog was introduced and when no frog was present. Tadpoles did not respond visually to a female frog physically separated from them by transparent Plexiglas. However, tadpoles were more active in water conditioned by female frogs than in unconditioned water. Tadpole activity was further elevated by water conditioned by a female frog and tadpoles. Tadpoles were more active in water conditioned by male frogs than in unconditioned water, but water conditioned by a male frog and tadpoles did not further elevate tadpole activity. Thus, water conditioned by adults of either sex contains substances that increase tadpole activity, but only females show a synergistic effect with conditioning by tadpoles. Copyright 2002 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour     

Effects of the epibiotic heterotrich ciliate Mirofolliculina limnoriae and of moulting on faecal pellet production by the wood-boring isopods, Limnoria tripunctata and Limnoria quadripunctata

The heterotrich ciliate Mirofolliculina limnoriae occurs in an obligate association with wood-boring species of the isopod Limnoria. It attaches to the dorsal surface of the limnoriid pleotelson. Folliculinid-bearing populations of Limnoria tripunctata from the Ria Formosa, Portugal, and of Limnoria quadripunctata from Portsmouth, UK, were sampled. Up to four folliculinids were found on one individual of L. quadripunctata and up to twelve on L. tripunctata. There was no evidence that folliculinid load increased with host size. The nature of the epibiont/basibiont relationship was examined by observing animals with and without epibionts, kept individually with small sticks of wood in cell culture wells over periods of up to 15 days. Faecal pellet production and moulting were recorded. In both host species, feeding rate as measured by faecal pellet production was significantly lower in animals bearing folliculinids. Feeding rate also diminished with the onset of moulting, but returned to the original rate within a week after moulting. The estimated intermoult period for the population of L. tripunctata examined was about 25 days and for L. quadripunctata was about 32 days. However, the proportion of individuals moulting over the period of observation declined with increasing size in L. tripunctata, suggesting increasing length of intermoult period with age. As the host faces toward the blind end of its tunnel and ventilates the burrow with its pleopods, the folliculinids are well placed to intercept particulate food in the incoming water stream. There are no clear advantages for the host in the association, but the suppression of feeding and the potential of the folliculinids to hinder swimming during dispersal migrations indicate that the association should be viewed as ectoparasitism rather than mutualism or commensalism.     

Temperature acclimation in Actinia equina L. (Anthozoa)

Respiratory adaptation to different sea temperatures on the Natal (east) and Table Bay (west) coasts of southern Africa is demonstrated in Actinia equina L. Animals are able to acclimate to lower sea temperatures but are unable to adapt to an increase of 3 °C or more above summer sea temperatures. Acclimation to elevated water temperatures may be limited by thermal sensitivity of the tissues and by lack of feeding when under thermal stress.The successful colonization of the Natal littoral zone by A. equina may be attributed partially to metabolic adaptability but also to its brooding ability, tolerance of desiccation, and capacity to retain water within the coelenteron. Slow exudation of this water enables evaporative cooling of the tissues during low tide. Other actinian species from Natal lack this range of features and are hence limited to damp habitats at lower tidal levels.     

Field reproductive dynamics of the invasive slipper limpet, Crepidula fornicata

At least part of the invasive success of the slipper limpet, Crepidula fornicata, in European waters must be due to reproductive characteristics, yet the events underlying the easily-observed brooding and non-brooding periods have not yet been studied in this species. The reproductive system dynamics were therefore investigated using topological histology and quantitative histological techniques. Specimens were sampled twice monthly for 18 months from Bourgneuf Bay, France, a mid-latitudinal point in the European distribution of C. fornicata. Both the testicles and ovaries showed active and resting phases, corresponding to the brooding and non-brooding periods, respectively. Maximum spermatozoan production corresponds to the female brooding period (female incubation of oviposited eggs, mid-March to late August), and allows males to possess full spermatozoan stocks at the height of fresh mature oocyte availability. The year-round presence of mature oocytes in the female gonad is misleading, since the histological aspect reveals that they are vestigial oocytes which slowly degenerate during the brooding period, possibly providing metabolites for the developing oocytes that become increasingly abundant during this period. A complete scheme of the C. fornicata reproductive cycle is presented, showing the events in the major reproductive organs.The seminal vesicle shows high inter-month variability in sperm presence, suggesting year-round copulation and sperm storage in the seminal receptacle. The seminal receptacle shows a uniform covering of spermatozoa throughout the year, suggesting rapid renewal after fertilization, again in line with multiple copulation throughout the year. Given the limited available space on the seminal epithelium, against which all spermatozoa abut, as well as polyandrous copulation, it is postulated that sperm competition may take place.     

Tetrachyrin,a new rearranged kaurenoid lactone,and diterpene acids from Tetrachyron orizabaensis and Helianthus debilis

(?)-Kaur-16-en-19-oic acid and tetrachyrin, a new rearranged kaurenoid lactone, were isolated from Tetrachyron orizabaensis var. websteri and Helianthus debilis ssp. debilis. The latter species also afforded angeloylgrandifloric acid.     

Oxygen consumption and the respiratory responses to declining oxygen tension in the crab Ebalia tuberosa (Pennant) (Crustacea: Decapoda: Leucosiidae)

Oxygen consumption and its relationship to body weight and activity have been examined in Ebalia tuberosa (Pennant). Ebalia showed only very limited ability to regulate their oxygen consumption under conditions of declining P_O2. Respiratory independence was markedly affected by the level of activity of the animals. When inactive, respiratory independence was maintained down to a critical P_O2 of only about 130 mm Hg while when active, the crabs behaved as perfect conformers. Inactive Ebalia responded to a decrease in PO₂ by increasing the pumping activity of the scaphognathites and heart. This increased activity continued even at oxygen tensions lower than the P_c. The rate of reversals of the ventilatory currents did not change with decreasing P_O2. In the active crabs, the pumping activity of the scaphognathites and heart, and the rate of current reversals were higher than in the inactive animals, and a decrease in PO₂, did not bring about any further change in any of these responses. When exposed to hypoxic conditions for long periods initially inactive crabs survived longer than did active animals.     

Inhibitory effects of leachate from Eupatorium adenophorum on germination and growth of Amaranthus retroflexus and Chenopodium glaucum

Amaranthus retroflexus L. and Chenopodium glaucum L. are two widely distributed destructive weeds. Their strong adaptability and massive seed production make them the hardest weeds to deal with. This present study intended to investigate the effect of leachate from Eupatorium adenophorum on the growth of these weeds and explore the potential to develop an environmental friendly strategy to use the leachate to control the weeds. Seeds of A. retroflexus L. and C. glaucum L. were soaked in solutions containing 0%, 0.6%, 1.25%, 2.5%, and 5% leachate from E. adenophorum leaves. A. retroflexus and C. glaucum seedlings grown in pots were sprayed with leachate solutions in the same concentration range. The effects of these leachate solutions on membrane permeability and germination of seeds, and growth and physiological characteristics of the seedlings were investigated. The highest concentration of leachate (5%) caused significant damage to the cell membrane of seeds of both weed species, whereas lower concentrations (0.6%) promoted repair of the membrane system, as reflected by higher and lower than control in relative conductivity (RC), respectively. Different concentrations of leachate showed distinct allelopathic inhibitory effects on the two weed species; lower concentrations showed weak inhibitory or even positive effects, whereas higher concentrations showed stronger inhibitory effects. Higher concentrations of leachate (2.5% and 5%) delayed germination and significantly decreased the emergence rate of the seeds, survival rate, and dry matter accumulation of the seedlings. When treated by 5% leachate, the emergence date of A. retroflexus was delayed by 3.6 d, emergence rate of the seeds and survival rate was 69.1% and 70.6% of the control, respectively, seedling dry matter was 48.6% less than the control; In the case of C. glaucum, the emergence date was delayed by 2.7 d, emergence rate of the seeds and survival rate was 45.1% and 58.6% of the control, respectively, seedling dry matter was 44.7% less than the control. There were significant interactions among the different concentrations of leachate and the length of treatment period with respect to activities of antioxidant enzymes, malondialdehyde (MDA) contents, and chlorophyll contents. Seedlings treated with 0.6%, 1.25%, or 2.5% leachate solution for 24–72 h showed increased superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities. When seedlings were treated with leachate solutions for 96 h, antioxidant enzyme activities and chlorophyll content decreased in A. retroflexus, but only CAT activity decreased in C. glaucum. When seedlings of the two weed species were treated with 5% leachate solution, CAT activity and chlorophyll content decreased and MDA content gradually increased with longer treatment times (from 24 to 96 h). The two weed species showed different allelopathic responses to E. adenophorum; A. retroflexus was more sensitive than C. glaucum. Based on the investigation, it could be speculated that the delayed germination and low germination rate of the weeds after treatment by leachate could be due to the fact that leachate damaged the membrane system of the seeds. By delaying germination, lowering the germination rate of the weeds and inhibiting seedling growth, leachate from E. adenophorum could provide an effective way of controlling the weeds.     

Temporal pattern of sex pheromone release by female Trichoplusia ni

The release rate of the pheromone component Z-7-dodecenyl acetate was determined for individual female Trichoplusia ni by using small glass tubes filled with Porapak Q to extract pheromone from air in the immediate vicinity of the everted gland. The change in release rate as a function of time was determined by taking sequential 5 min. samples from individual 4-day-old females through each pheromone release period over an entire night. The release rate was found to decline exponentially from a mean of 22 ng per min. initially to 12 ng per min. at the end of 20 min., the average length of a pheromone release period. Pheromone collections were also made from females of different ages, using a single tube of Porapak per female to collect pheromone for an entire night. The nightly mean release rate increased significantly with age, although the time spent releasing pheromone per night decreased significantly with age (to 6 days old).     

Lavandula angustifolia essential oil as a novel and promising natural candidate for tick (Rhipicephalus (Boophilus) annulatus) control

Lavandula angustifolia is a well known herbal medicine with a variety of useful properties, including its acaricidal effect. This experiment was carried out to study the bioacaricidal activity of L. angustifolia essential oil (EO) against engorged Rhipicephalus (Boophilus) annulatus (Acari; Ixodidae) females. For this purpose six serial concentrations (0.5, 1.0, 2.0, 4.0, 6.0 and 8.0% w/v) of L. angustifolia EO were used. There was considerable mortality in concentrations more than 4.0% although there were no differences between 6.0 and 8.0% in all measured criteria. The mortality rate 24 h after inoculation was 73.26 and 100% in groups treated with 4.0 and 8.0% EO, respectively. Lavender EO also reduced tick egg weight in a concentration-dependent manner. The amount of eggs produced varied from 0.12 g (at 0.5% EO) to 0.00 g (at 8.0% EO) but did not differ statistically from the control. L. angustifolia EO caused 100% failure in egg laying at 6.0 and 8.0% whereas this value in the control group was zero. A positive correlation between L. angustifolia EO concentration and tick control, assessed by relative mortality rate and egg-laying weight, was observed by the EO LC/EC₅₀, which, when calculated using the Probit test, was 2.76-fold higher than the control. Lavender is a promising acaricidal against R. (B.) annulatusin vitro.     

水产用聚维酮碘对异育银鲫养殖的安全性评价

评价水产用聚维酮碘对异育银鲫(Carassius auratus gibelio)养殖的安全性,为其在异育银鲫养殖中的安全应用提供了重要的科学依据,本研究参照国家标准及相关法规,在观察了聚维酮碘对小球藻(Chlorella sp.)生长抑制作用、对水产益生菌抑菌效果以及对大型蚤(Daphnia magna straus)、斑马鱼(Brachydanio rerio)和异育银鲫的急性毒性的基础上,分析其对异育银鲫及其养殖水体主要有害理化因子的影响.实验结果表明,聚维酮碘在终浓度为6.00 ～ 14.00 mg/L时对小球藻生长具有促进作用,对小球藻的半数抑制浓度大于14.00 mg/L,对水产益生菌的最小抑菌浓度为128～512 mg/L,对大型蚤、斑马鱼的半数致死浓度分别为13.44 mg/L、17.63 mg/L.此外,聚维酮碘对异育银鲫的半数致死浓度为74.77 mg/L,而且在养殖水体中加入聚维酮碘至终浓度为0.20 ～ 1.40 mg/L后14 d内,随着聚维酮碘浓度的增加,各浓度组异育银鲫养殖水体的氨氮含量、亚硝酸盐含量均缓慢下降.本研究证实聚维酮碘低毒,但考虑到其可能对异育银鲫养殖水体中大型蚤等浮游动物存在潜在影响,建议其在异育银鲫养殖中的安全应用浓度应不高于1.34 mg/L,在该安全应用浓度内不会引起养殖水中氨氮、亚硝酸盐等有害因子含量的增加.     

A comparative study on the tubes and feeding behaviour of eight species of corophioid Amphipoda and their bearing on phylogenetic relationships within the Corophioidea

Observations are presented on mouthpart functional morphology, and on feeding, grooming and defaecatory behaviour of eight species of corophioid Amphipoda, viz. Corophium bonnellii, Lembos websteri, Aora gracilis, A. spinicornis, Gammaropsis nitida, Ericthonius punctatus, Jassa falcata and J. marmorata. These data are considered in relation to tube structure and amphipod posture in relation to the tube. All these species occupy double-ended cylindreical tubes made from ''amphipod silk'' secreted by the third and fourth preraeopods, incorporating sediment and other debris to varying degrees. Uniquely among this set of species, however, E. punctatus has a tube that is architecturally distinct. It tapers along its length and has a distinctive oblique main entrance at its widest end. This end is used preferentially. The other species studied use either opening with equal facility. Such a feature is adaptive in facilitating deployment of the antennae and shielding the head of E. punctatus.Two groupings of species are propose: group A which feed inside their tube using pleopod-induced through-tube currents, and group B which feed outside or at the entrance to their tube using external water currents. Group A includes C. bonnellii, L. websteri and the Aora species. Group B includes E. punctatus and the Jassa species. Gammaropsis nitida exhibits traits from both groups, adding weight to its perceived status as a genus representative of the stem corophioid. The ischyrocerid habit of externalizing food-gathering may be regarded as the first step along an evolutionary line leading to the rod-building podocerid types and ultimately towards the caprellids. All species examined show a degree of flexibility in their feeding habits which helps to explain the success of this taxon, which has radiated into a great diversity of aquatic biotopes.     

Sorptionsmessungen an den beiden Schabenarten Periplaneta americana und Blaberus trapezoideus

The absorption rate of adult males of the two cockroaches Periplaneta americana and Blaberus trapezoideus has been investigated by weight measurements and a tracer method.Both species loose weight in 26°C and 33%, 53%, 78%, and 98% relative humidity, and they finally die after a weight loss of 25 to 35%. Even in a high air humidity there is always a certain loss of weight. This weight loss masks the small absorption rate—shown by tracer methods—which increases disproportionally with rising humidity. The absorption represents probably a passive transport because narcotized animals show the same rate of absorption as normal insects. Also, there is a reduction of the absorption rate during exposure time. The water exchange between the animal and its atmosphere is therefore likely to lead to an equilibrium between the radioactive atmosphere and the unlabelled body water.Absorption occurs over the whole body surface. The amount absorbed via the posterior wing and the anus has no ecological significance. P. americana shows a higher cuticular permeability than B. trapezoideus.     

The reproductive biology of the deep-sea asteroids Benthopecten simplex (Perrier), Pectinaster filholi Perrier,and Pontaster tenuispinus Düben & Koren (phanerozonia : benthopectinidae) from the rockall trough

Samples of three species of benthopectinid starfish were collected in a time-series from stations in the northern Rockall Trough. A detailed study was made of the reproductive biology of Benthopecten simplex (Perrier) from a fixed station at 2200 m. Studies of the gametogenic cycles of Pectinaster fllholi Perrier and Pontaster tenuispinus Düben & Koren from less regular and more scattered samplings are also presented.The oogenic cycles of the three species are similar. Growing oocytes line the ovary wall and come to lie in the lumen only when well developed. Accessory cells surrounding young oocytes become more numerous as the oocytes develop. Vitellogenesis begins when oocyte diameter reaches ≈ 250–300 μm and oocytes attain a maximum diameter of 950 μm in Benthopecten simplex, 850 μm in Pectinaster filholi, and 800 μm in Pontaster tenuispinus. Unspent oocytes are broken down by phagocytes and degenerate ovaries become filled with the breakdown products. Internal degeneration of large oocytes is not common.Size frequency data show a dominance of previtellogenic oocytes and a pattern of continuous growth of vitellogenic oocytes. There is no evidence of synchrony of growth between individuals and no suggestion of seasonal reproduction is evident from summated sample data.Spermatogenesis follows the pattern previously established for deep-sea asteroids. A mature male remains in a state of constant ripeness, ready to shed sperm at any chance encounter with a female releasing ripe eggs. There is no evidence of brooding in any of the species and from the large size and yolk content of the egg, we can infer direct lecithotrophic development demersally.