Egg Development Time Research Articles

Variation in developmental rates is not linked to environmental unpredictability in annual killifishes.

Comparative evidence suggests that adaptive plasticity may evolve as a response to predictable environmental variation. However, less attention has been placed on unpredictable environmental variation, which is considered to affect evolutionary trajectories by increasing phenotypic variation (or bet hedging). Here, we examine the occurrence of bet hedging in egg developmental rates in seven species of annual killifish that originate from a gradient of variation in precipitation rates, under three treatment incubation temperatures (21, 23, and 25°C). In the wild, these species survive regular and seasonal habitat desiccation, as dormant eggs buried in the soil. At the onset of the rainy season, embryos must be sufficiently developed in order to hatch and complete their life cycle. We found substantial differences among species in both the mean and variation of egg development rates, as well as species‐specific plastic responses to incubation temperature. Yet, there was no clear relationship between variation in egg development time and variation in precipitation rate (environmental predictability). The exact cause of these differences therefore remains enigmatic, possibly depending on differences in other natural environmental conditions in addition to precipitation predictability. Hence, if species‐specific variances are adaptive, the relationship between development and variation in precipitation is complex and does not diverge in accordance with simple linear relationships.

Amblypygi parthenogenesis, embryonic and post-embryonic development: a case study with the Amazonian species Charinus guto Giupponi and Miranda, 2016 (Amblypygi: Charinidae)

ABSTRACT Parthenogenesis is documented in a few species of Amblypygi, but it is unknown how widespread in the order this reproductive behaviour is, and little has been researched regarding aspects of embryonic and post-embryonic development in the group. Here, we studied the parthenogenetic capacity of an Amazonian whip spider (Charinus guto) evaluating the time of egg and embryonic development and inter-moult period. We also provide a review on embryonic and post-embryonic development in Amblypygi, compiling and analysing data from 43 species in three families. Fifty-two females and 42 juveniles of C. guto were collected in fragments of a secondary forest in Belém (Brazil); specimens were kept in captivity and observed weekly from 2018 to 2020. Nineteen specimens were collected with and 32 without egg sacs. Fourteen of the non-ovigerous females developed eggs in captivity, six of them moulted (i.e. lost stored sperm from previous contacts with males) before developing an egg sac, proving to be parthenogenetic. The mean time between the first day in captivity and moult was 96 days. In both adults and juveniles, a mean of 147 days passed between first day in captivity and first moult, and 125 days for a second moult. After moulting, a mean of 113 days passed for the females to develop an egg sac; the embryonic development took a mean of 59 days. Juveniles left the mother’s abdomen after 10 days of hatching from the egg and the mean number of live free-living protonymphs was five. Other amblypygids, especially charinids, have similar embryonic development and post-embryonic growth and a detailed discussion with all known information for whip spiders is presented. We also demonstrate a positive correlation between clutch size and female size across Amblypygi, in which larger females carry more eggs and have larger offspring regardless of climate and habitat.

The role of environmental factors in the realization of the epidemic process on ascariasis

Introduction. Ascariasis is one of the most common parasitic diseases that infect about 1.5 million people in the world every year. In Russia, from 40 to 60 thousand cases are registered annually. To make effective management decisions on sanitary-epidemiological and preventive measures, the search for environmental factors that potentially affect the epidemic process of ascariasis in the Vladimir region was carried out. Materials and methods. The study analyzed archived statistical data on the incidence of ascariasis in the population, the state of the environment (air, water, and soil pollution), the socio-economic situation (unemployment rate, average salary, number of doctors and nurses, housing provision), as well as climate indices (average monthly temperature, number of days in a month with precipitation, humidity and snow cover) in the region. Statistical data processing and correlation and regression analysis were performed using the Statistica software. The maps were built and edited using the ArcView 3.1 GIS program and the standard Paint computer program. Results. The incidence of ascariasis in the region is characterized by significant diversity. Statistically reliable correlations of morbidity with environmental indices were obtained, and a mathematical equation was constructed using linear regression to predict the level of morbidity in the region. Conclusion. In the epidemiology of ascariasis in the Vladimir region, a leading role retains climatic, environmental indices determining the possibility of developing eggs of ascarids in the environment to the infective stage. A regional factor that affects the epidemiological process (indirectly through the suppression of the protective functions of the child’s body and reducing the development time of Ascaris eggs) is air pollution by stationary objects. The data obtained can assess the risk of infection with ascariasis to ensure biological safety in the region.

Short-term lethal and sublethal atrazine effects on Litoditis marina: towards a nematode model for marine toxicity assessment?

Organochlorine pesticides are still widely used in many regions of the world, despite their toxic properties to many organisms, including humans, and their high environmental persistence in waters and sediments. In order to properly assess contaminant effects across trophic levels in aquatic communities, the responses of different model organisms should be investigated. Particularly for marine benthic environments, relatively few model organisms for the assessment under controlled laboratory conditions of both lethal and sublethal effects are available. Here we investigate the use of a cryptic species of the free-living nematode Litoditis marina as a model organism for short-term tests of the impacts of contaminants, using the case of the herbicide atrazine. Its ease of culturing, short generation time and high fecundity render L. marina PmIII a good candidate to assess contaminant effects for both a rapid assessment of impacts and more detailed investigations of the mechanisms behind those effects. The LC50 of atrazine to adult L. marina PmIII was 3.3 ± 0.5 mg/L after a 5-day exposure, suggesting a comparatively higher sensitivity of this species compared to other aquatic invertebrate model species, mainly crustaceans. This LC50 was less than half the value after a 4-day exposure and was 22-fold lower than the 48 h LC50, demonstrating the importance of performing lethality tests for as long an exposure time as possible. Sublethal effects were observed at much lower atrazine concentrations and encompassed, from 0.8 mg/L onwards, impairment of life-history traits (reduced fecundity and extended egg deposition and development times) and population parameters (abundances of juveniles and adults, adult sex ratio). These sublethal effects were broadly consistent among different life-history traits and population parameters, but fecundity and the maximum abundances of juveniles, adults and total nematodes were the most sensitive response variables. We therefore suggest that an adequate assessment of sublethal contaminant effects on L. marina requires a combination of different life-history traits and population-level parameters. We conclude that L. marina PmIII is a suitable model species for ecotoxicological research encompassing both lethal and sublethal effects, and can as such contribute to environmental risk assessment in marine and estuarine systems.

Effects of Temperature and Relative Humidity on the Embryonic Development of Hypera postica Gyllenhal (Col.: Curculionidae)

The combined effect of the temperature and relative humidity on the survival and development time of the eggs of Spanish populations of the weevil Hypera postica, a key pest of alfalfa around the world, was evaluated under laboratory conditions. The experimental temperatures ranged from 8 to 36 °C, in 4 °C increments. Three relative humidity ranges were defined: high, medium, and low. Eggs of the alfalfa weevil successfully developed until larval emergence at all of the 24 conditions tested. However, the temperature and relative humidity affected the survival of the eggs. The egg developmental time decreased as the temperature increased from 8 to 32 °C, and the longest time was recorded at a low relative humidity (RH). The relationship between the development rate and temperature fit well to the lineal model for relative humidity. The minimum development threshold (T0) and the thermal requirement for egg development (K) ranged between 3 and 4 °C and 209 and 246 degree-days, respectively. According to these values and the occurrence of eggs and larvae (in winter) and adults (in autumn) in field samplings, the period of oviposition was determined. The results of the study contribute to better understanding the annual cycle and phenology of H. postica in the Iberian Peninsula and southern Europe.

Temperature induced changes in the development of embryos and paralarvae of the merobenthic octopus, Octopus tetricus

Incubation temperatures can extend or decrease the time required for the embryos of marine invertebrates to hatch, while also greatly influencing the morphology and survival of hatchlings, characteristics which are of critical importance in hatchery production. This study examines the effect of incubation temperatures (16, 19, 22, 25 °C and ambient seawater temperature) on the development time to hatch, egg morphometric ontogeny and the hatching success in the common Sydney octopus, Octopus tetricus. These parameters were assessed at regular intervals for eggs from three broods placed in artificial incubation tanks at four temperatures between 16 and 25 °C, while the remainder of the eggs for each of the broods were incubated in ambient seawater under female care. The time to hatch had an inverse relationship to incubation temperature with the egg development time to hatch being halved at 25 °C (26–32 days) compared to 16 °C (67–69 days). Despite the markedly different development times there were no differences in the survival or quality of the resulting hatched paralarvae, although there was an overall tendency for inner yolk sac volume to decrease with increasing rearing temperature but not consistently among broods. There were differences in the number, size and quality of embryos in the three broods which tended to persist throughout their development, but these did not appear to be related to the size of the female octopus or water temperature prior to egg laying. The overall hatching success of eggs in artificial incubation tanks was above 90% for the brood of one female (F1) while for the other two it was 71% (F3) and 57% (F2) mostly likely as a direct result of being compromised by infection of the egg strings. Improvements in hatchery practice is required to prevent such infections for future paralarval production. The results demonstrate a wide thermal tolerance for the early developmental stages of O. tetricus with the potential to manipulate egg incubation temperatures to better meet the timing of hatchery production requirements.

Evaluation of silver nanowires (AgNWs) toxicity on reproductive success of Daphnia magna over two generations and their teratogenic effect on embryonic development

This study assessed the reproductive toxicity of silver nanowires (AgNWs) in Daphnia magna over two consecutive generations. An acute immobilization test was conducted according to the ΟECD 202 guidelines. To perform reproductive toxicity tests in both F0 and F1 generations, the animals were exposed to different concentrations of AgNWs (0, 0.4, 2, 10, and 50 µg L−1) and pyriproxyfen (0.4 µg L−1), as a positive control, based on the ΟECD 211 principles. Overall, AgNWs were acutely toxic to D. magna with EC50 value of 0.063 mg L−1. Compared to the control groups, AgNWs disrupted reproductive performances of D. magna through increasing the egg development time and time to production of first brood as well as decreasing the total offspring production and molting frequency in both F0 and F1 generations. After exposure to AgNWs, the number of male neonates and non-reproductive females increased in the F0 generation, whereas just male neonates raised in the F1 generation. Moreover, AgNWs caused several congenital anomalies including underdeveloped antennae, 2nd antennae, malpighian tube, rostrum, sensory bristles, tail spine, and malformed eyes. Together, AgNWs could disrupt reproductive health of D. magna, and these types of bioperturbations could dramatically change the good health state of aquatic ecosystems.

Overwintering biology of the predatory bug, Orius vicinus (ribaut) (Hemiptera: Anthocoridae) under outdoor conditions in the eastern mediterranean region of Turkey

Overwintering biology of Orius vicinus (Ribaut) (Hemiptera: Anthocoridae) was investigated between November 2017 and April 2018 in the Balcali location of Adana Province, Turkey under outdoor conditions. The duration of egg and nymphal development time, pre-oviposition, oviposition and post-oviposition periods of females, the number of eggs laid and adults longevity were determined by the experiments performed in the first day of each experimental month under the outdoor conditions at the Department of Plant Protection, Faculty of Agriculture, University of Cukurova. The duration of egg hatching lasted between 5 and 10 days in all months of experiment and the tested eggs were hatched even at low temperature and under short day length conditions. More than half of the nymphs obtained from the tested eggs became adults in the winter months. Despite the nymph’s survival was affected negatively by the sudden changes in temperature, they were tolerant to the low temperatures and short-day lengths during the winter period. All females in the trials oviposited for about 30 days even in the coldest periods (approximately 15 °C). The females were not affected by the environmental conditions particularly in winter season, and they did not undergo reproductive diapause. The obtained data shed light on the overwintering biology of O. vicinus which may be helpful for their potential role in controlling the non-diapaused pest species such as pest thrips in the early spring season.

Reproductive output and larval survival of American dog ticks (Dermacentor variabilis) from a population at the northern distributional limit.

Female reproductive output and larval survival were determined for American dog ticks, Dermacentor variabilis (Say), from a recently established population near the northern distributional limit in Saskatchewan (Canada). Oviposition took 10-21days at 25°C and 95% relative humidity (RH). Temperature and relative humidity had a marked effect on egg development time and larval survival. Unfed larvae survived more than 100days at 32°C (with 95% RH) and 25 and 5°C (with ≥ 85% RH). However, survival times declined markedly at lower relative humidities. In addition, 95% of the larvae placed in field enclosures survived for 140days over winter during which they were exposed to sub-zero temperatures and 95-100% RH, while covered with snow. The median survival times (LT50) of unfed larvae submerged underwater was 68days. These results show that D. variabilis larvae in populations near the periphery of the northern distributional limit are adapted to cope with sub-zero temperatures in winter, and can survive in the temporary pools of water created by the spring snow melt.

Effect of alternative rearing substrates and temperature on growth and development of the cricket Modicogryllus conspersus (Schaum)

The increasing demand for animal protein in sub-Saharan Africa has led to insects being considered an alternative protein source for food and feed. In Uganda, chicken mash, containing fish meal as the protein source is commonly used to rear crickets. However, fishmeal is an expensive protein source that is also human food. This study therefore aimed at establishing an alternative preferred (consumed in the highest quantity) plant leaf diet for raising the Modicogryllus conspersus cricket, and the most suitable temperature for hatchability and egg development. The effect of (a) three diets (cassava leaves + cocoyam leaves + milk weed leaves; cassava leaves + pumpkin leaves + wandering Jew; and cassava leaves + lablab + Cinderella weed) on growth; and (b) incubation temperature (26, 28, 30, 32, and 34 °C) on egg hatchability and egg development time were studied. Cassava, pumpkin and milk weed leaves were the most ‘preferred’ of the tested plant leaves. Egg development time was longer at lower temperatures, ranging between 7-14 days across a 26-34 °C temperature range. The highest hatchability (95%) was observed at 28 °C, below and above which hatchability decreased. The maximum nymph weight (1.58 mg) at hatching was observed at 26 °C and decreased with increasing egg incubation temperature. The plant leaf diet containing leaves with highest protein content (pumpkin, wandering Jew and cassava) led to the highest growth and growth rate comparable to the control diet (broiler chick mash). Temperature had a significant effect on egg development time (P<0.001) and nymph weight at hatching (P<0.001) while the food type significantly influenced growth (P<0.001) and moulting time. The possibility of formulating a nutrient balanced, cost-effective, compound feed for cricket production should be investigated.

Quantifying species traits related to oviposition behavior and offspring survival in two important disease vectors.

Animals with complex life cycles have traits related to oviposition and juvenile survival that can respond to environmental factors in similar or dissimilar ways. We examined the preference-performance hypothesis (PPH), which states that females lacking parental care select juvenile habitats that maximize fitness, for two ubiquitous mosquito species, Aedes albopictus and Culex quinquefasciatus. Specifically, we examined if environmental factors known to affect larval abundance patterns in the field played a role in the PPH for these species. We first identified important environmental factors from a field survey that predicted larvae across different spatial scales. We then performed two experiments, the first testing the independent responses of oviposition and larval survival to these environmental factors, followed by a combined experiment where initial oviposition decisions were allowed to affect larval life history measures. We used path analysis for this last experiment to determine important links among factors in explaining egg numbers, larval mass, development time, and survival. For separate trials, Aedes albopictus displayed congruence between oviposition and larval survival, however C. quinquefasciatus did not. For the combined experiment path analysis suggested neither species completely fit predictions of the PPH, with density dependent effects of initial egg number on juvenile performance in A. albopictus. For these species the consequences of female oviposition choices on larval performance do not appear to fit expectations of the PPH.

Biology, morphology and damage of the lesser Coconut weevil, Diocalandra frumenti (Coleoptera: Curculionidae) in southern Vietnam

Abstract. Nguyen HU, Nguyen TH, Chau NQK, Le VV, Tran VH. 2020. Biology, morphology and damage of the lesser coconut weevil, Diocalandra frumenti (Coleoptera: Curculionidae) in southern Vietnam. Biodiversitas 21: 4686-4694. The lesser coconut weevil, Diocalandra frumenti, is an emerging pest of coconut trees in Vietnam. To help develop control options for D. frumenti, this study investigated its morphological and biological characteristics, and quantified damage levels on coconut trees. Results from the study showed that attack by D. frumenti on coconut trees is correlated with characteristic damage symptoms (e.g., oozing sap) on all maturity stages of coconut fruits throughout the year (24.7% infestation), with higher damage levels on young fruits (57.6%). Results also showed that infestation levels on trees (58.9%), coconut bunches (19.4%), and fruits (7.77%) varied greatly. Adults have four different morphologies, but genetic study showed that they are all one species. The life cycle from egg to adult averaged 167± 34.3 days. The average development time for eggs, larvae, female pupae, male pupae, male adults, and female adults was 5.62 ± 0.62, 142.3 ± 34.3, 9.79 ± 0.86, 10.2 ± 1.26, 81.5 ± 34.7, and 81.8 ± 37.2 days, respectively. In conclusion, D. frumenti is an important pest in coconut trees with significant fluctuations in the duration of its development stages, and variation in shape, color, and size of the eggs, larvae, pupae, and adults. They can attack any coconut orchard and have harmful impacts on coconut trees, coconut bunches, and fruits throughout the year.

Influence of the temperature and humidity on the development time of eggs and immature stages of Lygus pratensis (Linnaeus, 1758) (Heteroptera: Miridae) in Primorsky krai.

Influence of the temperature and humidity on the development time of eggs and immature stages of Lygus pratensis (Linnaeus, 1758) (Heteroptera: Miridae) in Primorsky krai.

Optimal estimation of lice release from aquaculture based on ambient temperatures

Models for mapping and forecasting infective pressure from salmon louse Lepeophtheirus salmonis larvae are of major importance in the Norwegian government’s management of salmonid aquaculture. These models use site-reported temperature and number of egg-producing female adult lice present within cages to calculate how many lice eggs and larvae are released from individual farms. The reported temperature is critical in this calculation, as temperature influences both frequency of ‘spawnings’ and egg developmental time until hatching. Farms report temperature measured at 3 m depth, as defined by regulation. However, the salmon themselves, and therefore also the attached female lice and their eggs, often swim deeper to meet their preferred temperature within the water column. This study compares calculated lice egg production based on reported temperature at 3 m depth to calculated lice egg production based on a hydrodynamic ocean model of temperature stratification and salmon-preferred temperature in the modelled stratifications. The results clearly show that present legislated routines with farm site temperature measurements at 3 m depth lead to underestimation of egg and larvae production in winter and overestimation in summer for a range of sites. Future mitigating management and models of lice output should use the temperature measured or modelled for the depths the salmon predominantly occupy.

Temperature dependent survival and fecundity of Lepidelphax pistiae Remes Lenicov (Hemiptera: Delphacidae), a potential biological control agent of Pistia stratiotes L. (Araceae)

ABSTRACTLepidelphax pistiae Remes Lenicov (Hemiptera: Delphacidae) is monophagous on Pistia stratiotes L. (Araceae), an invasive floating plant in Florida. Temperature studies were conducted to determine the optimal temperature for development and reproduction for this potential biological control agent. Egg development time decreased as temperature increased from 17°C to 30°C. No eggs developed and no nymphs survived at 15°C. Adult females survived the longest at 15°C, indicating that they might be more resilient to cold temperatures. Optimal temperature for nymph development was 25°C with 29% surviving to adulthood in 18.2 ± 0.4 days.

Effects of dietary protein:carbohydrate balance on life‐history traits in six laboratory strains of Drosophila melanogaster

AbstractDrosophila melanogaster Meigen (Diptera: Drosophilidae) is a key model insect for studying life span and aging. Many laboratory strains of D. melanogaster are currently used by laboratories worldwide, but they are known to vary considerably in their physiology, behavior, and life histories. Although the importance of dietary protein:carbohydrate (P:C) balance as a predominant determinant of life span and other life‐history traits has been highlighted in recent research, it remains unexplored whether the impacts of P:C balance on these fitness‐related traits vary in a strain‐specific manner in D. melanogaster. In this study, we compared the life‐history consequences (life span, egg production rate, pre‐adult survival, development time, and body mass at eclosion) of six laboratory strains of D. melanogaster (w1118, yw, Oregon‐R, white Canton‐S, Canton‐S‐SNU, and Canton‐S‐Inha) allocated to one of four synthetic diets differing in P:C ratio (1:16, 1:4, 1:1, or 4:1). The effects of dietary P:C balance on various adult and larval life‐history traits were qualitatively similar across all strains studied in this study. Regardless of fly strain, adults exhibited a shortened life span and improved egg production on a diet with the highest P:C ratio of 4:1. In all strains, larvae raised on a diet comprising the lowest P:C ratio of 1:16 suffered high mortality, delayed development time, and reduced body mass. Despite the general similarity in the direction of the effect of P:C balance across strains, fly strains differed in the magnitude of their life‐history responses to dietary P:C balance, as indicated by a significant interaction between fly strain and dietary P:C ratio for all measured traits except body mass at eclosion. Possible mechanisms explaining such strain‐specific responses are discussed.

Demography of the land snail Tikoconus (Tikoconus) costarricanus (Stylommatophora: Euconulidae) in tropical low montane and premontane forests, Costa Rica

Abstract. Introduction: Ecology and natural history of neotropical land snails is almost unknown. Objetive: In this paper I analyse the population dynamics of Tikoconus (Tikoconus) costarricanus Barrientos, in prep., an understory endemic euconulid. Methods: I compared T. costarricanus’ demography patterns in tropical montane forests in central Costa Rica in three habitats with different restoration techniques: a mature forest, a secondary forest and a Cuppressus lusitanica plantation. I collected data in three month periods during a year. I analysed population size in relation with habitat, sampling date, leaf litter humidity, depth and quantity; and specimen size in relation with habitat and sampling date. I also kept some specimens in terraria and described part of their natural history. Results: The species is more abundant in mature forest (Ø = 0.174 ind/m2). The number of specimens in each habitat was constant throughout the year (Kruskall-Wallis = 2.0118, p = 0.57, NS) and hatching occurs in the middle and last months of the rainy season (Kruskall-Wallis = 17.3061, p = 0.00061, **). Number of specimens is related with leaf litter humidity (Spearman correlation, r = 0.3524, n = 232, p = 0.000, **), amount (Spearman correlation, r = 0.3922, n = 232, p = 0.000, **) and depth (Spearman correlation, r = 0.2543, n = 232, p = 0.000, **). This relationship is explained by the high and stable humid environment provided by leaf litter. During the drier months some specimens migrate from the foliage to the leaf litter. Eggs (Ø = 1mm) are laid on moss or soil and the young spend the first 2 or 3 weeks of their life on moss. Egg masses are small (Ø = 4 eggs), and shells look bubbly. Egg development time (20 days) was longer than in other tropical species. Adult pigmentation appears around two months after hatch. In the only case observed egg laying began 5 months after hatching and the specimen lived 9 months. Conclusions: Although no conclusive, these data point to a fragile species susceptible to habitat and climate change. Restorations techniques should consider leaf litter features in order to protect endemic neotropical humid dependent diversity.

Effect of temperature on egg development time and productivity of Acartia steueri and population variations of family Acartiidae in Dadaepo Beach, Busan, Korea

Effect of temperature on egg development time and productivity of Acartia steueri and population variations of family Acartiidae in Dadaepo Beach, Busan, Korea

Effects of temperature during successive generations on life-history traits in a seed beetle Callosobruchus chinensis (Chrysomelidae: Coleoptera)

Temperature is an important environmental factor for life-history traits in poikilothermic animals. Many of experiments on evolution have been conducted using Drosophila species, and effects on life-history traits vary depending on the study. On the other hand, few studies have been conducted on the effects of temperature on life-history traits in the other insect species. In the present study, we reared adzuki bean beetles under two different temperatures, high and low, for 2 years (20 generations), and compared life-history traits including body size of females, fecundity, egg size, rate of egg hatching, emergence rate, development time, and wing length. No differences in responses were found in these traits between selection strains, except the rate of egg hatching. That is, the rates of egg hatching in high-temperature (32 °C) selection strains were significantly higher than those in low-temperature (24 °C) selection strains. We discuss the cause of change in egg hatchability during successive generations under different temperature treatments from the following viewpoints including evolutionary adaptation to high temperature and the experimental protocol.

In situ Monitoring of Longfin Inshore Squid Egg Deposition and Embryonic Development

Knowledge of squid early life history is relatively poor despite its importance for fisheries management. The longfin inshore squid Doryteuthis pealeii (Lesueur, 1821) is a commercially important species harvested extensively along the northeastern United States continental shelf. To understand the effects of fishing and environmental variability on D. pealeii in an inshore spawning ground (Nantucket Sound, MA), egg deposition and embryonic development were monitored in situ at commercial fish weirs in spring and summer 2008 to 2016. Logbooks were maintained in which catch (including the presence of egg masses) and effort data for each weir were recorded daily. Seawater temperature was recorded using data loggers affixed to the weirs. Newly deposited egg masses were transferred to a mesh enclosure on an opportunistic basis and placed immediately adjacent to the weir to permit semiweekly retrieval and sampling. Samples (five randomly chosen “fingers” excised from a mass) were chilled and transported to a nearby wet lab for microscopic examination to determine embryonic development stage. Hatch timing was determined via direct observation of paralarvae emerging from egg masses and development time was calculated as the number of days between egg mass deposition and hatching. The timing and duration of egg mass deposition varied between years. Embryonic development time of 15 egg masses ranged from 12 to 34 days and generally decreased at warmer temperatures. In situ observations were consistent with the findings of laboratory studies of D. pealeii and other loliginid squids.