Geophilus flavus

The consumption behaviours of G. flavus are regulated by seasonal and circadian rhythms.[5] These rhythms affect the metabolic and physiological processes of the species, particularly during periods of hibernation or food scarcity.[5] Soil communities are greatly impacted by seasonal or temporal changes, and changes in climate result in altered feeding patterns.[18] In periods of increased temperature and soil dryness as a result of season or from ongoing climate change, G. flavus displays higher rates of food consumption.[18] Increased temperatures facilitate higher nutrient and carbon cycling, as well as increased litter decomposition.[18] These decomposition processes increase the production of bacteria and fungi, key dietary components of the secondary consumers that G. flavus preys upon.[19] The centipede's control over trophic cascades and direct feeding interactions is increased by rising temperatures.[19] Conversely, during colder months when prey is less abundant and G. flavus is less active, feeding interactions increase across the entire soil community.[5] During these periods of decreased activity, G. flavus has less top-down predator control over smaller invertebrates.[2] The centipede instead accumulates reserve materials in the fat body for delayed nutrient absorption.[5] G. flavus enters a hibernation state where fat structures change in order to support long-term sustenance.[19]

The diet of G.flavus is relatively generalised, and is flexible depending on available food sources.[19] Gut content analysis of the centipede reveals high levels of lumbricid and enchytraeid proteins, nutrient markers of small soil earthworms.[19] G.flavus predominantly preys upon smaller invertebrates such as worms, mites and insect larvae.[4] Occasionally, if food sources are scarce G.flavus feeds on plant material, or other centipedes.[7] The size and type of prey G.flavus consumes vary across different aged and sized centipedes.[19] Larger centipedes have higher mobility, and can move greater distances in the soil environment, thus they have access to a wider range of prey than smaller centipedes.[19]

G. flavus inhabits a diverse range of organic structures including soil, rocks, trees, bark and decomposing leaf litter.[5] The species dwells in porous underground soil structures alongside other small invertebrates.[3] This environment provides an ample food source and is relatively buffered against extreme fluctuations in temperature and moisture.[20] The texture and thickness of the leaf litter above the soil surface provides structural niches which facilitate microhabitats and a diversity of small invertebrates that G.flavus hunts.[21] The nature and structure of the habitat is a large determinant of predator-prey relationships, as denser organic layers increase the search time required for centipedes to locate prey.[4]

G. flavus generally avoids light and displays a distinct preference for moister habitats.[20] It is a cryptozoic species, and spends most of the daytime under stones and leaf litter, waiting until night time to hunt.[10] Depending on the season, G. flavus will burrow at different depths in the soil. In wetter, more tropical weather, the centipede will burrow closer to the surface of the soil at around 7 cm.[10] In dryer weather, the centipede burrows at a deeper depth between 7–14 cm.[10] G. flavus moves through the soil similarly to earthworms, expanding their length forward, and then contracting in order to pull their body towards their head.[12] This movement creates soil tunnels and burrows, allowing the flow of air and water towards underground plant roots.[12] G. flavus in more temperate regions are generally perennial, living longer with a lower reproductive potential than their tropical counterparts.[10]

This study investigates the nature of the fat body structure in soil centipedes, looking specifically at G.flavus. The study, conducted in 2019, is the first academic paper to investigate the fine structure of the fat body organ in Chilopoda, finding that unlike insects, this structure is not regionally distinct and the fat body is distributed through the entire body cavity.[5] To prove this, researchers collected centipedes from their habitats and placed them into artificial environments which simulated temperature and humidity conditions of a particular season.[5] After several weeks in a specific condition, the centipedes were dissected and examined under a microscope using protein, lipid and glycogen stains. Researchers showed that the fat body in centipedes was constituted by irregular lobular masses of adipocytes, containing organelles responsible for nutrient synthesis.[5] These adipocytes are exclusively responsible for the accumulation and regulation of reserve material in G.flavus.[5] The quantity and nutrient density of this accumulation is directly impacted by the season.[5] G.flavus kept in a Winter condition, placed into a fridge, showed significantly higher quantities of reserve accumulation than those in Spring conditions. This material is exploited via the adipocytes through digestion and autophagy, allowing the centipede to survive through extended periods of hibernation and inactivity. Prior to this study, the only formally recorded information about the fat body in centipedes was from a study in 1898.[5]

This study from 2017 provides an outline of the centipede fauna of Southwestern Siberia, mapping the distribution of the G.flavus species.[23] Based on prior taxonomy studies, the species is supposedly new to the fauna of Western Siberia.[23] The study somewhat refutes this claim, hypothesising that G.flavus may have been introduced through the East of Urals several decades ago based on recent distribution and botanical reports.[23] The study also notes that G.flavus may have been falsely categorised as G.proximous in previous USSR reports, making it unclear whether or not the species is new to Western Siberia.[23]

Another, more general, study from 2005 details the distribution and prevalence of Geophilomorpha, and G.flavus in Latvia. This study involved the collection and inspection of various centipedes across a range of habitats in Latvia.[15] The research provides a framework for species identification, and outlines some of the key morphological features of G.flavus. Of 21 collected specimens, the maximum length was 5 cm.[15] The leg bearing segments were between 49 and 55 in males, and 51–57 in females. G.flavus were predominantly found in grasslands and open fields, as well as urban parks and greenhouses.[15] These descriptions largely aligned with previous documentation by De Geer in 1778, stipulating antennae more than 3 times as long as the head and usually less than 60 leg bearing segments.[15] The research also indicates a common prevalence of G.flavus compared to other Geophilomorpha in the Baltic region, hypothesising this may be due to their large ecological tolerance.[15]