Benzodiazepine Interference with Fertility and Embryo Development: A Preliminary Survey in the Sea Urchin Paracentrotus lividus.

Psychotropic drugs and benzodiazepines are nowadays among the primary substances of abuse. This results in a large and constant release into aquatic environments where they have potentially harmful effects on non-target organisms and, eventually, human health. In the last decades, evidence has been collected on the possible interference of benzodiazepines with reproductive processes, but data are few and incomplete. In this study, the possible negative influence of delorazepam on fertilization and embryo development has been tested in Paracentrotus lividus, a key model organism in studies of reproduction and embryonic development. Sperm, eggs, or fertilized eggs have been exposed to delorazepam at three concentrations: 1 µg/L (environmentally realistic), 5 µg/L, and 10 µg/L. Results indicate that delorazepam reduces the fertilizing capacity of male and female gametes and interferes with fertilization and embryo development. Exposure causes anatomical anomalies in plutei, accelerates/delays development, and alters the presence and distribution of glycoconjugates such as N-Acetyl-glucosamine, α-linked fucose, and α-linked mannose in both morulae and plutei. These results should attract attention to the reproductive fitness of aquatic species exposed to benzodiazepines and pave the way for further investigation of the effects they may exert on human fertility. The presence of benzodiazepines in the aquatic environment raises concerns about the reproductive well-being of aquatic species. Additionally, it prompts worries regarding potential impacts on human fertility due to the excessive use of anxiolytics.

Parentage influence on gene expression under acidification revealed through single-embryo sequencing.

The dissolution of anthropogenic carbon dioxide (CO2 ) in seawater has altered its carbonate chemistry in the process of ocean acidification (OA). OA affects the viability of marine species. In particular, calcifying organisms and their early planktonic larval stages are considered vulnerable. These organisms often utilize energy reserves for metabolism rather than growth and calcification as supported by bulk RNA-sequencing (RNA-seq) experiments. Yet, transcriptomic profiling of a bulk sample reflects the average gene expression of the population, neglecting the variations between individuals, which forms the basis for natural selection. Here, we used single-embryo RNA-seq on larval sea urchin Heliocidaris crassispina, which is a commercially and ecologically valuable species in East Asia, to document gene expression changes to OA at an individual and family level. Three paternal half-sibs groups were fertilized and exposed to 3 pH conditions (ambient pH 8.0, 7.7 and 7.4) for 12 h prior to sequencing and oxygen consumption assay. The resulting transcriptomic profile of all embryos can be distinguished into four clusters, with differences in gene expressions that govern biomineralization, cell differentiation and patterning, as well as metabolism. While these responses were influenced by pH conditions, the male identities also had an effect. Specifically, a regression model and goodness of fit tests indicated a significant interaction between sire and pH on the probability of embryo membership in different clusters of gene expression. The single-embryo RNA-seq approach is promising in climate stressor research because not only does it highlight potential impacts before phenotypic changes were observed, but it also highlights variations between individuals and lineages, thus enabling a better determination of evolutionary potential.

Modulation of stress factors for cryopreservation of Paracentrotus lividus (Lamarck 1816) larvae.

In the present work we modulated two stress factors salinity and temperature, whose ranges have been previously determined by bioassays using six pre-treatments (18 °C-29.5‰; 18 °C-35‰; 18 °C-39‰ and 20 °C-29.5‰; 20 °C-35‰; 20 °C-39‰), in order to obtain a successful cryopreservation protocol for pluteus larvae of the sea urchin P. lividus (Lamarck 1816). Toxicity tests were performed with different cryoprotectants in a range of 0.5-3 M. Best results pointed out to METH and Me2SO as those more suitable for cryopreservation. First an exploratory cryopreservation experiment with Me2SO supplemented with 0.04 M trehalose (TRE) was tested following the protocol for cryopreservation of embryos (8-h blastula) of Bellas and Paredes, 2011, which did not give satisfactory results. A cryopreservation experiment was performed with both cryoprotectants supplemented with 0.04 M trehalose on 4-arm pluteus larvae (48 h-old) developed in these pre-treatment conditions, followed by a simpler and shorter protocol with a cooling rate of 1 °C/min to -35 °C, achieving for the first time the successful cryopreservation of P. lividus larvae. When larvae were incubated in low salinity or low temperature pre-treatments, they showed delayed larval development and abnormalities. In contrast, pretreatments with high temperature and salinity showed good results. Dimethyl sulfoxide with trehalose proved to be the only effective cryoprotectant for successful cryopreservation of P. lividus larvae. The success of dimethyl sulfoxide is consistent with that described for other cases in previous literature, where dimethyl sulfoxide, although not the least toxic compound, gave the best cryopreservation result.

Impact on Fertility Rate and Embryo-Larval Development Due to the Association Acidification, Ocean Warming and Lead Contamination of a Sea Urchin Echinometra lucunter (Echinodermata: Echinoidea).

Ocean warming and acidification can cause deleterious effects on marine biota, which may be potentialized when associated with metal pollution. Thus, the aim of this work was to evaluate the effects of pH decrease, temperature increase and lead contamination on fertility rate and embryo-larval development of Echinometra lucunter. Gametes and embryos were exposed at pH 8.2 (control) and 7.5; at 26°C (control) and 28°C; and at lead concentrations of 0 (control), 125, 250 and 500 µg/L. These conditions were tested individually and in combination. The fertilization rate of E. lucunter was only significantly reduced in the treatments where temperature was increased and in the treatment where pH decreased. However, the development rate of the pluteus larvae was significantly affected in the majority of treatments: metal contamination in the higher concentration; decreased pH in all metal concentrations; increased temperature in the highest metal concentration; decreased pH and increased temperature and all variables combined, which is decreased pH, increased temperature and metal contamination in relation to the control group (C). The development test was shown to be more sensitive than the fertilization test in all the studied scenarios. In general, the present study suggests that pH decrease, temperature increase and metal pollution may have a significant impact on E. lucunter reproductive cycle.

Immunohistochemical and ultrastructural properties of the larval ciliary band-associated strand in the sea urchin Hemicentrotus pulcherrimus.

BACKGROUND: The swimming activity of sea urchin larvae is dependent on the ciliary band (CB) on the larval surface and is regulated by several neurotransmitters, including serotonin (5HT), dopamine, and γ-aminobutyric acid (GABA). However, the CB signal transmission mechanism remains unknown. The present study investigated the structural relationship between the CB and external signal receptors by immunohistochemical and transmission electron microscopic analyses of sea urchin, Hemicentrotus pulcherrimus, larvae. RESULTS: Glutamate decarboxylase (GAD; GABA synthetase) was detected in a strand of multiple cells along the circumoral CB in 6-arm plutei. The GAD-expressing strand was closely associated with the CB on the oral ectoderm side. The ciliary band-associated strand (CBAS) also expressed the 5HT receptor (5HThpr) and encephalopsin (ECPN) throughout the cytoplasm and comprised 1- to 2-µm diameter axon-like long stretched regions and sporadic 6- to 7-µm diameter bulbous nucleated regions (perikarya) that protruded into the oral ectoderm side. Besides the laterally polarized morphology of the CBAS cells, Epith-2, which is the epithelial lateral cell surface-specific protein of the sea urchin embryo and larva, was expressed exclusively by perikarya but not by the axon-like regions. The CBAS exposed its narrow apical surface on the larval epithelium between the CB and squamous cells and formed adherens junctions (AJs) on the apical side between them. Despite the presence of the CBAS axon-like regions, tubulins, such as α-, ß-, and acetylated α-tubulins, were not detected. However, the neuroendocrine cell marker protein synaptophysin was detected in the axon-like regions and in bouton-like protrusions that contained numerous small ultrastructural vesicles. CONCLUSIONS: The unique morphology of the CBAS in the sea urchin larva epithelium had not been reported. The CBAS expresses a remarkable number of receptors to environmental stimuli and proteins that are probably involved in signal transmission to the CB. The properties of the CBAS explain previous reports that larval swimming is triggered by environmental stimuli and suggest crosstalk among receptors and potential plural sensory functions of the CBAS.

Ontogenetic changes in larval swimming and orientation of pre-competent sea urchin Arbacia punctulata in turbulence.

Many marine organisms have complex life histories, having sessile adults and relying on the planktonic larvae for dispersal. Larvae swim and disperse in a complex fluid environment and the effect of ambient flow on larval behavior could in turn impact their survival and transport. However, to date, most studies on larvae-flow interactions have focused on competent larvae near settlement. We examined the importance of flow on early larval stages by studying how local flow and ontogeny influence swimming behavior in pre-competent larval sea urchins, Arbacia punctulata We exposed larval urchins to grid-stirred turbulence and recorded their behavior at two stages (4- and 6-armed plutei) in three turbulence regimes. Using particle image velocimetry to quantify and subtract local flow, we tested the hypothesis that larvae respond to turbulence by increasing swimming speed, and that the increase varies with ontogeny. Swimming speed increased with turbulence for both 4- and 6-armed larvae, but their responses differed in terms of vertical swimming velocity. 4-Armed larvae swam most strongly upward in the unforced flow regime, while 6-armed larvae swam most strongly upward in weakly forced flow. Increased turbulence intensity also decreased the relative time that larvae spent in their typical upright orientation. 6-Armed larvae were tilted more frequently in turbulence compared with 4-armed larvae. This observation suggests that as larvae increase in size and add pairs of arms, they are more likely to be passively re-oriented by moving water, rather than being stabilized (by mechanisms associated with increased mass), potentially leading to differential transport. The positive relationship between swimming speed and larval orientation angle suggests that there was also an active response to tilting in turbulence. Our results highlight the importance of turbulence to planktonic larvae, not just during settlement but also in earlier stages through morphology-flow interactions.

Leachates of weathering plastics from an urban sandy beach: Toxicity to sea urchin fertilization and early development.

Plastic leachates have chemical and biological implications for marine environments. This study experimentally evaluated acute effects of weathering plastic leachates (0, 25, 50, 75 and 100 %) on fertilization and early development of the sea urchin Lytechinus variegatus. Fertilization, embryonic and larval development were drastically inhibited (~75 %) when gametes were exposed to intermediate and high leachate concentrations or delayed when exposed to the lowest concentration. Fertilization and first cleavage stages were highly affected by exposure to intermediate and high leachate concentrations. None of the cells incubated at concentrations from 50 % reached blastula stage, suggesting that embryonic development was the most sensitive stage. Abnormalities in embryos and larvae were observed in all leachate treatments. Chemical analysis detected high concentration of bisphenol A, which may induce these observed effects. Our results highlight the potential threats of plastic pollution to sea urchin populations, which may severely affect the structure and functioning of coastal ecosystems.

Microplastics impede larval urchin selective feeding.

Microplastics are emergent threats to marine organisms as ingestion can cause a multitude of physiological problems. Suspension feeders, including marine invertebrate larvae, are particularly susceptible to ingesting microplastics due to similarities in physical appearance to algal cells. Larval feeding involves multiple stages: the capture and subsequent selection of particles followed by ingestion from the mouth to the stomach, digestion, and finally, egestion. Yet, little is known about which aspect of the feeding process is disrupted by microplastics. Here, we determine if prior exposure to microplastics alters the feeding behavior of the larval sea urchin Heliocidaris crassispina. We conducted two experiments: a food handling experiment studied larval survival, growth, and time required to fill and vacate the stomach; and a particle selection experiment analyzed changes in the ability of the larvae to selectively ingest algal cells over microplastics. In both experiments, larvae were pre-exposed to algae only (control), the addition of 10 µm polystyrene beads at 1 bead mL-1 or 1000 beads mL-1 until 3- or 7-days post-fertilization. Previous exposure to microplastics lengthened stomach filling time and impaired particle selection. While there was no significant change in survivorship and larval arm length, these sub-lethal impacts on larval feeding likely have more severe ramifications in vivo where food is limited, and thus, potentially threaten post-settlement success.

A detailed comparison of two species in the genus Potamanthus Pictet, 1843 from China (Ephemeroptera, Potamanthidae).

Photographs and details of structures of two Potamanthus species, P.huoshanensis Wu, 1987 and P.luteus (Linnaeus, 1767), are presented for the first time. Here, based upon Chinese specimens of those species, all external structures are illustrated digitally and compared. The results and photos clearly show that the adults of the two species are different in wing color and genitalia shape, and that their nymphs have different mandibular tusks and forelegs. Specifically, P.luteus has a more colorful body and wings, longer penes and nymphal mandibular tusks but shorter foretarsi than those of P.huoshanensis. This comparison not only confirms the differences between these two similar species, but also supports the updated generic delineations of Potamanthus and Potamanthodes.

GC-MS analysis, antidiabetic and antioxidant activity of methanolic extract of pluteus cervinus: an in vitro and in silico approach.

Pluteus cervinus is a mushroom species that demands a systematic study of its medicinal values. This study aims to explore the mycochemical contents of Pluteus cervinus extract, and evaluate their anti-diabetic and antioxidant potency. Twelve organic compounds were identified using Gas Chromatogram-Mass Spectroscopy(GC-MS) analysis of the methanolic extract. All the mycochemicals identified were evaluated for their drug-likeness, pharmacokinetics and bioactivity using admetSAR and molinspiration webservers. The extract was evaluated for the inhibitory effect of α-amylase and DPPH free radical scavenging ability. To further support the anti-diabetic and antioxidant characteristic, in silico molecular docking analysis was done for all the identified mycochemicals. It was found that, 2-(3,4-dimethoxyphenyl)-N-[4-(4-methoxyphenyl)-tetrahydropyran-4-ylmethyl]-acetamide, one of the compounds in the extract shares structural similarity and comparable docking binding energy with natural α-amylase inhibitor. Further, the 2-(3,4-dimethoxyphenyl)-N-[4-(4-methoxyphenyl)-tetrahydropyran-4-ylmethyl]-acetamide also showed high binding energy with Human peroxiredoxin 5 and has a structural relationship with natural antioxidants containing tetrahydropyran derivatives.

Near future ocean acidification modulates the physiological impact of fluoxetine at environmental concentration on larval urchins.

Pharmaceuticals found in human wastes are emergent pollutants that are continuously released into aquatic systems. While exposure to pharmaceuticals alone could adversely impact aquatic organisms, few studies have considered the interactive effects of pharmaceuticals and the future environmental conditions, such as decreasing pH due to ocean acidification. Given the bioavailability of many pharmaceuticals is dependent on these physical conditions, we investigated the effect of environmentally-relevant concentrations of fluoxetine (10 and 100 ng L-1) under ambient (pH 8.0) and reduced pH conditions (pH 7.7) on physiology, behavior, and DNA integrity of larval sea urchins (Heliocidaris crassispina). Notably, the negative impacts of fluoxetine exposure were attenuated by reduced pH. Larvae exposed to both reduced pH and fluoxetine exhibited lower levels of DNA damage compared to those exposed to only one of the stressors. Similar antagonistic interactions were observed at the organismal level: for example, fluoxetine exposure at 10 ng L-1 under ambient pH increased the percentage of embryos at later developmental stages, but such effects of fluoxetine were absent at pH 7.7. However, despite the modulation of fluoxetine impacts under ocean acidification, control larvae performed better than those exposed to either stressor, alone or in combination. We also observed that pH alone impacted organismal behaviors, as larvae swam slower at reduced pH regardless of fluoxetine exposure. Our findings highlight the need to consider multi-stressor interactions when determining future organismal performance and that multiple metrics are needed to paint a fuller picture of ecological risks.

Temporal variability modulates pH impact on larval sea urchin development: Themed Issue Article: Biomechanics and Climate Change.

Coastal organisms reside in highly dynamic habitats. Global climate change is expected to alter not only the mean of the physical conditions experienced but also the frequencies and/or the magnitude of fluctuations of environmental factors. Understanding responses in an ecologically relevant context is essential for formulating management strategies. In particular, there are increasing suggestions that exposure to fluctuations could alleviate the impact of climate change-related stressors by selecting for plasticity that may help acclimatization to future conditions. However, it remains unclear whether the presence of fluctuations alone is sufficient to confer such effects or whether the pattern of the fluctuations matters. Therefore, we investigated the role of frequency and initial conditions of the fluctuations on performance by exposing larval sea urchin Heliocidaris crassispina to either constant or fluctuating pH. Reduced pH alone (pH 7.3 vs 8.0) did not affect larval mortality but reduced the growth of larval arms in the static pH treatments. Changes in morphology could affect the swimming mechanics for these small organisms, and geometric morphometric analysis further suggested an overall shape change such that acidified larvae had more U-shaped bodies and shorter arms, which would help maintain stability in moving water. The relative negative impact of lower pH, computed as log response ratio, on larval arm development was smaller when larvae were exposed to pH fluctuations, especially when the change was less frequent (48- vs 24-h cycle). Furthermore, larvae experiencing an initial pH drop, i.e. those where the cycle started at pH 8.0, were more negatively impacted compared with those kept at an initial pH of 7.3 before the cycling started. Our observations suggest that larval responses to climate change stress could not be easily predicted from mean conditions. Instead, to better predict organismal performance in the future ocean, monitoring and investigation of the role of real-time environmental fluctuations along the dispersive pathway is key.

The sea urchin Lytechinus variegatus lives close to the upper thermal limit for early development in a tropical lagoon.

Thermal tolerance shapes organisms' physiological performance and limits their biogeographic ranges. Tropical terrestrial organisms are thought to live very near their upper thermal tolerance limits, and such small thermal safety factors put them at risk from global warming. However, little is known about the thermal tolerances of tropical marine invertebrates, how they vary across different life stages, and how these limits relate to environmental conditions. We tested the tolerance to acute heat stress of five life stages of the tropical sea urchin Lytechinus variegatus collected in the Bahía Almirante, Bocas del Toro, Panama. We also investigated the impact of chronic heat stress on larval development. Fertilization, cleavage, morula development, and 4-armed larvae tolerated 2-h exposures to elevated temperatures between 28-32°C. Average critical temperatures (LT 50) were lower for initiation of cleavage (33.5°C) and development to morula (32.5°C) than they were for fertilization (34.4°C) or for 4-armed larvae (34.1°C). LT 50 was even higher (34.8°C) for adults exposed to similar acute thermal stress, suggesting that thermal limits measured for adults may not be directly applied to the whole life history. During chronic exposure, larvae had significantly lower survival and reduced growth when reared at temperatures above 30.5°C and did not survive chronic exposures at or above 32.3°C. Environmental monitoring at and near our collection site shows that L. variegatus may already experience temperatures at which larval growth and survival are reduced during the warmest months of the year. A published local climate model further suggests that such damaging warm temperatures will be reached throughout the Bahía Almirante by 2084. Our results highlight that tropical marine invertebrates likely have small thermal safety factors during some stages in their life cycles, and that shallow-water populations are at particular risk of near future warming.

Phylogenetic and morphological comparison of Pluteus variabilicolor and P. castri (Basidiomycota, Agaricales).

Based on several collections from Italy, a detailed description (including also macrophotographs, microphotographs, and drawings) of the morphological characters of the poorly known Pluteus variabilicolor, originally described from Hungary, is provided. The analysis of the ITS sequences placed this species within the P. leoninus clade of sect. Hispidoderma, in spite of the presence of clavate elements in the pileipellis. According to the molecular comparison of the type collections, Pluteus castri, a species recently described on the basis of material collected in Japan and Central Russia, is reduced to a synonym of P. variabilicolor.

Micetismos: Parte 4: Síndromes tempranos con síntomas complejos / Mushroom poisonings. Part 4: early-onset syndromes with complex symptoms / Intoxicações por cogumelos. Parte 4: Síndromes precoces com sintomas complexos

En esta Parte 4 de la serie de cuatro artículos sobre micetismos se analizan los síndromes que se caracterizan por presentar un período de latencia muy corto, con la aparición de síntomas complejos en menos de 6 horas después de la ingestión de los macromicetos. Se discuten los siguientes micetismos: 1) Toxíndrome muscarínico o colinérgico periférico por especies de Inocybe y Clitocybe. 2) Toxíndrome inmunohemolítico o hemolítico por Paxillus. 3) Toxíndrome neumónico alérgico por Lycoperdon perlatum y por Pholiota nameko. 4) Toxíndrome panterínico o neurotóxico glutaminérgico por compuestos isoxazólicos o síndrome pantherina/muscaria. 5) Toxíndrome coprínico o cardiovascular. 6) Toxíndrome neurotóxico alucinogénico por psilocibina y derivados indólicos. 7) Toxíndrome psicotrópico por estirilpironas y gimnopilinas de Gymnopilus spectabilis o G. junonius. 8) Toxíndrome agudo de rabdomiólisis por Russula subnigricans. 9) Toxíndrome cianogénico por Marasmius oreades. 10) Toxíndrome inmunosupresor por tricotecenos macrocíclicos de Podostroma cornu-damae. 11) Toxíndrome hemolítico debido a ostreolisina de Pleurotus ostreatus y especies relacionadas. Se analizan los síntomas, las toxinas involucradas, los mecanismos de acción, cuando se conocen, y las especies causantes de los micetismos.

This Part 4 of the series of four articles on mushroom poisonings refers to early-onset syndromes, which are characterized by a very short latency period, and the appearance of complex symptoms in less than 6 hours after mushroom ingestion. The following mycetisms are discussed, (1) Peripheral cholinergic, or muscarinic syndrome due to Inocybe and Clitocybe species. (2) Immunohaemolytic or haemolytic syndrome by Paxillus. (3) Allergic pneumonic syndrome due to Lycoperdon perlatum, and Pholiota nameko. (4) Glutaminergic neurotoxic, or pantherinic syndrome by isoxazole compounds or pantherina/muscaria syndrome. (5) Coprinic or cardiovascular syndrome. (6) Hallucinogenic neurotoxic syndrome due to psilocybin and indole derivatives. (7) Psychotropic syndrome by styrylpirones and gymnopilins of Gymnopilus spectabilis or G. junonius. (8) Rhabdomyolysis acute syndrome due to Russula subnigricans. (9) Cyanogenic syndrome by Marasmius oreades. (10) Immunosuppressive syndrome by macrocyclic trichothecenes of Podostroma cornu-damae. (11) Haemolytic syndrome due to ostreolisine of Pleurotus ostreatus, and related species. The symptoms, toxins involved, mechanisms of action, when known, and the species of mushrooms responsible for the mycetisms are analyzed.

Nesta parte 4 da série de quatro artigos sobre intoxicação por cogumelos são analisadas síndromes que se caracterizam por apresentar um período de latência muito breve, com aparecimento de sintomas complexos em menos de 6 horas após a ingestão dos macromicetos. As seguintes intoxicações com cogumelos são discutidas: (1) Toxíndrome muscarínico ou colinérgico periférico por espécies de Inocybe e Clitocybe. (2) Toxíndrome imuno-hemolítica ou hemolítica por Paxillus. (3) Toxíndrome pneumônica alérgica por Lycoperdon perlatum e por Pholiota nameko. (4) Toxíndrome panterínica ou neurotóxica glutaminérgica por compostos isoxazólicos ou síndrome pantherina/muscaria. (5) Toxíndrome coprínica ou cardiovascular (6) Toxíndrome neurotóxico-alucinogênica por psilocibina e derivados indólicos. (7) Toxíndrome psicotrópica por estirilpironas e gimnopilinas de Gymnopilus spectabilis ou G. junonius. (8) Toxíndrome aguda de rabdomiólise por Russula subnigricans. (9) Toxíndrome cianogênica por Marasmius oreades. (10) Toxíndrome imunossupressora por tricotecenos macrocíclicos de Podostroma cornu-damae. (11) Síndrome hemolítica por ostreolisina de Pleurotus ostreatus e espécies relacionadas. São analisados os sintomas, as toxinas envolvidas, os mecanismos de ação, quando conhecidos, e as espécies de cogumelos responsáveis pelas intoxicações.

Paracrias pluteus (Hymenoptera, Eulophidae) in Brazil: new distribution and host records, and with a new host group for Paracrias.

Bruchines damage agricultural crops and trees, reducing the quantity and quality of the seeds. The aim of this study is to record, for the first time, Paracrias pluteus as a parasitoid on the immature stages of Sennius spodiogaster and Sennius cupreatus on seeds of Melanoxylon brauna in Teixeiras, Minas Gerais State, Brazil. Paracrias pluteus is a parasitoid without previous host records and known only from Costa Rica. Specimens obtained in this study add to knowledge of the biology of Paracrias species with a new host group (Chrysomelidae: Bruchinae), and the first host record and a new distribution for Paracrias pluteus.

HETEROCHRONIC DEVELOPMENTAL PLASTICITY IN LARVAL SEA URCHINS AND ITS IMPLICATIONS FOR EVOLUTION OF NONFEEDING LARVAE.

Preexisting developmental plasticity in feeding larvae may contribute to the evolutionary transition from development with a feeding larva to nonfeeding larval development. Differences in timing of development of larval and juvenile structures (heterochronic shifts) and differences in the size of the larval body (shifts in allocation) were produced in sea urchin larvae exposed to different amounts of food in the laboratory and in the field. The changes in larval form in response to food appear to be adaptive, with increased allocation of growth to the larval apparatus for catching food when food is scarce and earlier allocation to juvenile structures when food is abundant. This phenotypic plasticity among full siblings is similar in direction to the heterochronic evolutionary changes in species that have greater nutrient reserves within the ova and do not depend on particulate planktonic food. This similarity suggests that developmental plasticity that is adaptive for feeding larvae also contributes to correlated and adaptive evolutionary changes in the transition to nonfeeding larval development. If endogenous food supplies have the same effect on morphogenesis as exogenous food supplies, then changes in genes that act during oogenesis to affect nutrient stores may be sufficient to produce correlated adaptive changes in larval development.