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Abstract While adult stomatopod crustaceans are relatively well studied, understanding of larval stomatopod ecology is lacking, largely due to difficulties studying larvae in their natural habitat. This study investigated how light environment (i.e., spectral composition) and time of day affected prey consumption in two species of larval stomatopod, Gonodactylaceus falcatus (Forskål, 1775) and Gonodactylellus sp. Individual larvae were placed with 20 Artemia nauplii prey in feeding chambers treated to produce different light environments with respect to ultraviolet (UV) light: full spectrum light UV+, full spectrum UV–, and a dark control. Chambers were lowered to a depth of 3 m for 2 hours at three times of day (noon, twilight, and night) to test 1) if larval feeding rates changed at different times of day and 2) if UV vision was involved in prey capture. We found that light was important for successful feeding, with both species eating significantly more in lighted treatments than the dark controls during daytime experiments. Gonodactylellus sp. also had a significantly higher feeding rate at twilight in the UV+ treatment than in the dark control. Both species showed decreased consumption at night compared to daytime rates, and decreased consumption in all dark controls. This study is one of the first to examine how ecological conditions affect feeding behavior in larval stomatopods. Our results suggest that light is important for larval stomatopod feeding, with differences between species in daily feeding activity periods. There was also a difference in total consumption between the two species, with the slightly larger Gonodactylaceus falcatus consuming nearly double the prey items as Gonodactylellus sp. at peak feeding times. Follow up studies should incorporate a variety of prey types to test how feeding changes based on food source and density.
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Air-Fluidized Aggregates of Black Soldier fly Larvae
Black soldier fly larvae are a sustainable protein source and play a vital role in the emerging food-waste recycling industry. One of the challenges of raising larvae in dense aggregations is their rise in temperature during feeding, which, if not mitigated, can become lethal to the larvae. We propose applying air-fluidization to circumvent such overheating. However, the behavior of such a system involves complex air-larva interactions and is poorly understood. In this combined experimental and numerical study, we show that the larval activity changes the behavior of the ensemble when compared to passive particles such as dead larvae. Over a cycle of increasing and then decreasing airflow, the states (pressure and height) of the live larva aggregates are single-value functions of the flow speed. In contrast, dead larva aggregates exhibit hysteresis characteristic of traditional fluidized beds, becoming more porous during the ramp down of airflow. This history-dependence for passive particles is supported by simulations that couple agent-based dynamics and computational fluid dynamics. We show that the hysteresis in height and pressure of the aggregates decreases as the activity of simulated larvae increases. To test if air fluidization can increase larval food intake, we performed feeding trials in a fluidization chamber and visualized the food consumption via x-ray imaging. Although the food mixes more rapidly in faster airflow, the consumption rate decreases. Our findings suggest that providing moderate airflow to larval aggregations may alleviate overheating of larval aggregations and evenly distribute the food without reducing feeding rates.
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- PAR ID:
- 10314324
- Date Published:
- Journal Name:
- Frontiers in Physics
- Volume:
- 9
- ISSN:
- 2296-424X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ABSTRACT Biphasic lifecycles are widespread among animals, but little is known about how the developmental transition between larvae and adults is regulated. Sea urchins are a unique system for studying this phenomenon because of the stark differences between their bilateral larval and pentaradial adult body plans. Here, we use single-cell RNA sequencing to analyze the development of Heliocidaris erythrogramma (He), a sea urchin species with an accelerated, non-feeding mode of larval development. The sequencing time course extends from embryogenesis to roughly a day before the onset of metamorphosis in He larvae, which is a period that has not been covered by previous datasets. We find that the non-feeding developmental strategy of He is associated with several changes in the specification of larval cell types compared to sea urchins with feeding larvae, such as the loss of a larva-specific skeletal cell population. Furthermore, the development of the larval and adult body plans in sea urchins may utilize largely different sets of regulatory genes. These findings lay the groundwork for extending existing developmental gene regulatory networks to cover additional stages of biphasic lifecycles.more » « less
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Abstract Interaction between sleep and feeding behaviors are critical for adaptive fitness. Diverse species suppress sleep when food is scarce to increase the time spent foraging. Post-prandial sleep, an increase in sleep time following a feeding event, has been documented in vertebrate and invertebrate animals. While interactions between sleep and feeding appear to be highly conserved, the evolution of postprandial sleep in response to changes in food availability remains poorly understood. Multiple populations of the Mexican cavefish,Astyanax mexicanus,have independently evolved sleep loss and increased food consumption compared to surface-dwelling fish of the same species, providing the opportunity to investigate the evolution of interactions between sleep and feeding. Here, we investigate effects of feeding on sleep in larval and adult surface fish, and two parallelly evolved cave populations ofA. mexicanus.Larval surface and cave populations ofA. mexicanusincrease sleep immediately following a meal, providing the first evidence of postprandial sleep in a fish model. The amount of sleep was not correlated to meal size and occurred independently of feeding time. In contrast to larvae, postprandial sleep was not detected in adult surface or cavefish, that can survive for months without food. Together, these findings reveal that postprandial sleep is present in multiple short-sleeping populations of cavefish, suggesting sleep-feeding interactions are retained despite the evolution of sleep loss. These findings raise the possibility that postprandial sleep is critical for energy conservation and survival in larvae that are highly sensitive to food deprivation.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fphy.2021.734447
