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Essay / Fog Beetle: Full Characteristics
Table of ContentsIntroductionDiscussionConclusionIntroductionMany creatures that live in the desert rely on some kind of special adaptation, and fog beetles have one of the strangest ways of finding food. water.Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essay The Namib Desert, where these beetles live, is located on the southwest coast of Africa (21°07´S 14°33´E) It is one of the driest regions of the world, receiving only 1.4 cm (0.55 in) of rain per year. The cold Benguela Current flows along the desert, creating the driest habitats on the planet. Water is essential to all living organisms and this harsh environment presents a major challenge to all forms of life. However, the cold coastal current not only suppresses precipitation over the desert, but also causes fog that can reach up to 100 km inland from the coast. But some species of tenebrinoid beetles living in the Namib Desert obtain water by drinking the water that condenses in mists. They can simply collect condensate from any surface, but some species exhibit behavioral adaptations to collect condensate. (Insects, their structure and function; RF Chapman; page 577). The benefit of fog collection for water intake in an extremely arid desert is obvious and critical when precipitation is absent for prolonged periods. Long-term studies of darkling beetle population density in the Namib Desert clearly show that mist-collecting beetles are still present in large numbers during periods of low rainfall, whereas the vast majority of darkling beetles lacking these adaptations disappear. or decrease. more than 1% of their average abundance (Norgaard and Dacke, Frontiers of Zoology, July 20, 2010). Here, four black beetles – Onymacris unguicularis, Onymacris laeviceps, Stenocara gracilipes and Physasterna cribripes were discussed. Some characteristics of fog beetles: Size: length up to 2 cm. Habitat: The Namib Desert in southwest Africa. Food: Any plant or animal material. Food is often hard to come by in the arid desert, so fog beetles have adapted to eating whatever they can find. Their sharp jaws can slice through plants and dead animals, and the tiny hairs in their mouths absorb moisture from food. Long legs: Long legs are essential to the existence of these beetles. Their legs hold their bodies above the burning sands of the desert. They also allow them to run at speeds of up to 3 feet per second and cover a lot of ground in the daily search for food. Shelter: Fogstand beetles need a way to protect themselves from the scorching sun from time to time. Without natural shelter in the desert, they bury themselves in the sand with their front legs and can disappear in seconds. Companion Marathon Runner: Male beetles pursue females during mating season, but females can outcompete them. If a male loses sight of a female after she digs in the sand at night, he will wait and headbutt any other males that approach to keep them away from his female. Distribution of desert beetles basking in the fog. Black Beetle Life Cycle: Beetles, like other insects, go through a complete process of metamorphosis in which they go through four stages ofdevelopment. Eggs: It begins when the female lays tiny white or yellow oval eggs. It usually takes 4 to 7 days for the eggs to hatch. Then they enter the “larval stage”. Larvae: At this stage, they eat a huge amount of food and continue to grow, shedding their exoskeleton several times as they grow. It takes approximately 3-7 weeks. It then enters the pupal stage. Pupa: It then enters the pupa stage, which can take up to 7 to 11 days. After pupation, an adult emerges. Adult: This beetle will then feed, mate and if it is female, it will lay eggs for the start of another generation. Their lifespan is generally around 2 years. Fig: life cycle of the mealworm What is fog basking behavior? To bask in the fog is to adapt a characteristic head-down position on the crests of the dunes and facing the fog-laden wind; water from the fog condenses on the back and then flows to the mouth where the condensate is absorbed (Hamilton & Seely, 1976; Seely, 1979). Strikingly, exposure to fog frequently occurs outside the normal activity period of this species, at ambient temperatures and wind speeds far removed from its preferences, and it is not known that it searches for food at these times (Seely et al., 1983; Louw et al., 1986). Sunbathing posture in the fog of Onymacris unguicularis. Photograph of an O. unguicularis basking in the fog inside the cloud chamber showing a characteristic head basking in the fog. This posture allows water from the mist collected on the beetle's dorsal surface to flow to its mouth. Mechanism of exposure to fog: · After a long night, when the air is cooled by the sea breeze, the sun rises to warm the Namib Desert. Turning toward the shore, the mist beetle uses its long hind legs to support its rear end in the air. The fog begins to form after a few minutes and a few drops of moisture appear on the beetle's body. After an hour of perfect stillness, the beetle's body is covered with dew and drops of water flow into its mouth. The mechanism by which fog water forms large droplets on a beaded surface has been described from the study of the elytra of beetles of the genus Stenocara [Parker A Lawrence CR]. The structures behind this process are thought to be hydrophilic peaks surrounded by hydrophobic zones; water carried by the mist settles on the hydrophilic peaks of the smooth bumps of the beetle's elytra and forms rapidly growing droplets that—once large enough to move against the wind—roll toward the head. Here systematic position of four tenebrinoid beetles are given: Comparison of fog basking behavior and water collection efficiency in these four dusky beetles from the Namib Desert: The fog collection behavior of four Tenebrionid beetle species have been compared: Onymacris unguicularis (Figure 1A) is known to bask in fog and has a smooth dorsal surface with broad grooves [7]. Onymacris laeviceps (Figure 1B) has a similar surface structure, but with finer grooves, and inhabits the same sand dune habitat as O. unguicularis. However, it is not known to bask in fog, but it drinks from fog-wet surfaces [Seely et al., 2005]. Stenocara gracilipes (Figure 1C) and Physterna cribripes (Figure 1D) are found outside sand dune habitat and have elytra with a more or less networkregular smooth bumps. It is a matter of debate whether or not either of these two species or genera basks in the fog[]. Size differences: Figure 1 Size difference between the four beetle models. Example specimens of each beetle species placed next to each other to compare size. A: O. unguicular, B: O. laeviceps, C:S. gracilipes, and D: P. cribripes. The dorsal surface area of P. cribripes was found to be 1.39 times larger than that of O. unguicularis, 1.56 times larger than that of O. laeviceps, and 2.52 times larger than that of S. gracilipes. Elytra surface structure: SEM images and photos taken under a dissecting microscope show details of the pronounced differences in elytra structure between the four beetle species). While the pronotum of all beetles is rather smooth, it is the elytra that have different structures. The elytra of O. unguicularis are almost completely smooth, except for the posterior half which has large, distinct grooves, about 0.5 mm wide, divided by narrow ridges. The elytra of O. laeviceps have much finer grooves (Figures 2B1), about 0.1 mm wide, which cover almost the entire elytra. The valleys of the fine grooves are not as smooth as those of O. unguicularis but rather have a coarser surface. In living animals, the posterior half of O. laeviceps has a blue-gray coloring. The elytra of the small S. gracilipes are covered with jagged bumps that form irregular lines, although there are also bumps between the lines. The elytra of large P. cribripes also have bumps that form irregular rows with additional bumps in between. The bumps are slightly rounder than those of S. gracilipes and are found on the entire elytra, with a smooth band on each side of the suture of the beetles' fused elytra.Structures of the elytra.A)Onymacris unguicularisB)Onymacris laevicepsC)Stenocara gracilipesD) Physasterna cribripes.A1-D1) Extended depth focus images of experimental animal examples obtained with a dissecting microscope. Scanning electron microscope images of the apex of the elytra. Figure: Hydrophobic dorsal surface of Physasterna cribripes Basking behavior in fog: Of the four beetles in the Namib Desert during a fog event, only O. unguicularis could be observed actively collecting water from the fog. In an experimental chamber, these beetles positioned themselves on top of a sand ridge and assumed a fog position after 114.5 ± 9.28 seconds. The starting point of this behavior was defined as the moment when O. unguicularis had turned its back towards the fog and then remained in this static position with its head tilted downward for at least 2 min. The ventral side of the beetle was held at an angle of approximately 23° from the horizontal during these events. In contrast, the other three beetle species continued to wander around the arena for the 20 minutes they were observed in the cloud chamber. These three species were therefore excluded from further behavioral experiments in the cloud chamber. The O. fog-basking unguicularis was tested again in the cloud chamber at temperatures equivalent to those that exist during natural fog events, this time without any fog in the chamber. In the absence of fog, O. unguicularis showed no fog behavior during the 20 min it was observed in the chamber. However, if the temperature was raised to room temperature and the chamber was filled with fog, six out of twelve beetles adopteda fog position after 175 ± 21.65 seconds. The other six beetles remained active and moving around for the 20 minutes they were there. observed, but never adopted a static standing head position. High humidity, rather than low temperature, is therefore the critical condition in which fog basking beetles adopt their characteristic position to collect water. However, a combination of fog and low temperatures is the strongest trigger for this behavior. Fog water collection efficiency: Regardless of whether or not they were able to actively collect fog water in the cloud chamber, the ability of the four beetle species to passively collect fog water was tested by scientists from dead specimens. Mounted upside down at an angle of approximately 23°. After two hours in the cloud chamber, Onymacris unguicularis and O. laeviceps, which have smooth elytra with grooves, collected 0.16 ± 0.03 and 0.11 ± 0.01 ml of water, respectively. Stenocara gracilipes and P. cribripes, which have elytra with a series of bumps, had, during the same time, collected 0.11 ± 0.01 ml and 0.14 ± 0.03 ml, respectively. Onymacris unguicularis and P. cribripes showed a tendency to harvest more fog water than O. laeviceps and S. gracilipes, but not significantly. Despite distinctly different elytron structures and behaviors, all four beetles collected the same amount of water over a 2-h period in the cloud chamber. The four beetle species vary in size, however. The relative sizes of the beetles' dorsal surface (the dorsal part of the head, the pronotum, and the elytra) were established from colored latex casts of the different beetles used in the water collection efficiency experiments. Scientists found that the dorsal surface area of the large P. cribripes is on average 1.39 times larger than that of the same region in O. unguicularis, 1.56 times larger than that of O. laeviceps, and 2.52 times larger larger than that of the smaller beetle S. gracilipes. By applying these relative differences in dorsal surface areas as conversion factors for the absolute amount of water collected per species, an estimate was obtained of the water collection efficiency of each species, independent of its size. Despite the fact that O. unguicularis is the only beetle in this study that actively collects fog water, it does not appear to be equipped with surface structures superior to those of other beetles. In fact, no significant difference in water collection per unit dorsal surface area can be found between O. unguicularis (0.22 ± 0.04 ml) and O. laeviceps (0.18 ± 0.01 ml), or O. unguicularis and S. gracilipes (0.27 ± 0.01 ml). 0.02 ml). The water collection efficiency of the large P. cribripes (0.14 ± 0.03 ml), however, is significantly lower than that of the fog-basking O. unguicular. Both the small (S. gracilipes) and the large (P. cribripes) have elytra with distinct bumps, but the water-gathering efficiency of these two beetles falls on the high and low end of the spectrum, respectively. , with a significant difference between the two. In fact, S. gracilipes harvested almost twice as much water per unit area (0.27 ± 0.02 ml) during the two hours spent in the cloud chamber compared to P. cribripes (0.14 ± 0.02 ml). .03 ml). Figure 5 Fog harvesting effectiveness. Freeze-killed beetles had their legs and antennae removed and were positioned upside down at a 23° angle in a cloud chamber. An Eppendorf tube to collect water was placed under the head of each beetle. After two hours in the room, the quantityTotal water captured by each of the four beetle species was measured (blue). The relative dorsal surface area of each beetle was determined and normalized to the largest beetle. This conversion factor was used to obtain the relative amount of water captured per dorsal surface area (red). Columns show mean ± SE. The columns marked with the corresponding lowercase letters above are not significantly different at p < 0.05 (Kruskal-Wallis test and Dunn's multiple comparisons test). fog in a small room (the temperature is around 10-12°, which is a similar temperature range to a fog event in the Namib Desert), the fog beetle O.unguicularis easily took his characteristic position of lounging in the fog after just over 2 minutes in the room. The static head position adopted by O. unguicularis while basking in the fog in the chamber was very similar for the same species while the fog was basking at the crest of a sand dune during an event fog in the Namib Desert. The other three beetles remained active but did not adopt a similar position at any time during their 20 minutes in the cloud chamber. The lack of fog basking behavior in these three beetle species is consistent with long-term observations of black beetles in the Namib Desert, [5] where only two of the approximately 200 beetle species inhabiting this area have ever been observed. fog-bask - both of the genus Onymacris. O. unguicularis basks easily and predictably in the same artificial environment, supporting the validity of the experimental setup. However, P. cribripes and many other darkling beetles will also adopt a tilted posture as a common alarm response [9]. The beetle then buries its head into the ground, spreads its legs wide and lifts the rear part of its body. This posture resembles a fog bath and could have been confused with this one in the study by Parker and Lawrence [10]. Fog was found to be the triggering factor for O. unguicularis basking in the fog. None of the twelve beetles adopted this position at low temperatures and without fog, but half of the O. unguicularis tested became exposed to fog when exposed to fog at around 23°C. In contrast, all O. unguicularis were placed in a mist-filled chamber. with fog at temperatures similar to a natural fog event in the Namib Desert [9] assumed a fog position. This indicates that temperature is a contributing, but not critical, factor in causing this behavior. The recorded tolerance for the variability of factors that trigger fog gathering also supports our conclusion that other beetle species do not engage in this behavior. Even if the temperature in the chamber had not been set at the absolute critical temperature to induce fog exposure behavior in O. laeviceps, S. gracilipes, or P. cribripes, the fog exposure position when it was placed in the cloud chamber was never observed. Water capture efficiency of beetle elytra: Experimental results reveal that the small beetle S. gracilipes is as efficient at harvesting water from fog, when measured per square unit of dorsal surface area, as the most large O. unguicularis, although it has never been actively observed. relax in nature [5] or in our cloud chamber. High efficiency of water collection.