Neotibicen Canicularis


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The genus Neotibicen comprises large-bodied Cicadidae appearing in late summer or autumn in North America. Many colloquial names exist for Neotibicen, including locust, and dog-day cicada. Until recently, these species were all in the genus Tibicen, which was redefined so as to include only a few European species, while species from the Western US and Mexico are now placed in a separate genus, Hadoa.

Neotibicen species are the most common cicada in the Eastern United States. Unlike periodical cicadas, whose swarms occur at 13- or 17-year intervals, Neotibicen species can be seen every year, hence their nickname “annual cicadas”. The life-cycle of an individual, however, is more than a year. Nymphs spend two or three years feeding on tree roots before they emerge. Their annual reappearance is due to overlapping generations.

Neotibicen cicadas are 1–2 inches (25–51 mm) long, with characteristic green, brown, and black markings on the top of the thorax, and tented, membranous wings extending past the abdomen. The fore pair are about twice the length of the hind pair. Adults feed using their beak to tap into the xylem of plants; nymphs feed from the xylem of roots.

Communication

Like other members of the subfamily Cicadinae, Neotibicen species have loud, complex songs, even (in many cases) distinct song phrases.

Males produce loud calls in the afternoon or evening (depending on the species) to attract females. These sounds, distinctive for each species, are produced by organs below the abdomen’s base. These calls range from a loud buzz to a long rattling sound.

Many animals feed on cicadas, which usually occurs during the final days when they become easy prey near the ground. One of the more notable predators is the cicada killer. This is a large wasp that catches the dog-day cicada. After catching and stinging the insect to paralyze it, the cicada killer carries it back to its hole and drags it underground to a chamber where it lays its eggs in the paralyzed cicada. When the eggs hatch, the wasp larvae feed on the paralyzed, but still living, cicada.

Bobbit Worm


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Eunice aphroditois (colloquially known as the Bobbit(t) worm), is an aquatic predatory polychaete worm dwelling at the ocean floor. This organism buries its long body into an ocean bed composed of gravel, mud, or corals, where it waits patiently for a stimulus to one of its five antennae, attacking when it senses prey. Armed with sharp teeth, it is known to attack with such speeds, its prey is sometimes sliced in half. Although the worm hunts for food, it is omnivorous.

According to Luis F. Carrera-Parra and Sergio I. Salazar-Vallejo, ecologists specializing in annelid polychaetes at El Colegio de la Frontera Sur in Campeche, Mexico, eunicids inject “…[a] narcotizing or killing toxin in their prey animal, such that it can be safely ingested — especially if they are larger than the worm — and then digested through the gut”. They further state, unlike a different family of worms, the fireworms (Amphinomidae), which have harpoon-shaped chaetae (bristles) that release a toxin that can cause severe skin irritation, E. aphroditois specimens “do not have abundant chaetae and their chaetae are not used for defensive purposes, but for improving traction for crawling over the sediment or inside their galleries or tubes”.

Little is known about the sexual habits and lifespan of this worm, but researchers hypothesize that sexual reproduction occurs at an early stage, maybe even when the worm is about 100 mm (3.9 in) in length; this is very early, considering these worms can grow to sizes of nearly 3 m (9.8 ft) in some cases (although most observations point to a much lower average length of 1 m (3 ft 3 in) and an average of 25 mm (0.98 in) in diameter). A long lifespan may very well explain the size of these creatures.

  1. aphroditois is found in warmer oceans around the world, including the Indo-Pacific and Atlantic.

In aquaria

Bobbit worms may be accidentally introduced into artificial environments. In March 2009, the Blue Reef Aquarium in Newquay, Cornwall, discovered a Bobbit worm in one of their tanks. The workers had seen the devastation caused by the worm, such as fish being injured or disappearing and coral being sliced in half, but did not find it until they started taking the display apart in the tank. The worm was nicknamed “Barry”.

Another Bobbit worm, three and a half feet long and a few inches thick, was found October 7, 2013 in Maidenhead Aquatics in Woking, Surrey.

Name

The name “Bobbit worm” was coined in the 1996 book Coral Reef Animals of the Indo-Pacific, in reference to Lorena Bobbit, who was then very much in the public consciousness. The name is inspired only by the scissorlike jaws of the worm; the common supposition that female eunicids cut off the males’ penises is false. In fact, the worms lack penises entirely as they are broadcast spawners.

Robber Flies


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The robber flies are an abundant and diverse family (Asilidae) known for their predatory behavior. Asilidae diversity can be attributed to their broad distribution, as most species tend to occupy a selective niche. As their common name implies, robber flies have voracious appetites and feed on a vast array of other arthropods, which may help to maintain a healthy balance between insect populations in various habitats (Joern and Rudd 1982, Shurovnekov 1962). Asilidae adults attack wasps, bees, dragonflies, grasshoppers, other flies, and some spiders. Robber flies are particularly abundant in arid and sunny habitats, which are optimal conditions in which to observe their many morphs and behaviors.

Distribution

The Asilidae enjoy a worldwide distribution, with some groups limited to certain regions (Hull 1962). For instance, the genera Megapodinae are unique to the Neotropical region. Large island chains tend to encompass abundant asilid faunas, particularly those south of Asia. By contrast, smaller islands such as the Hawaiian chain have no indigeous or introduced species (Hull 1962). The majority of robber fly species are found in dry, sandy conditions, as confirmed by the diversity of species found in such locales. Some species are well adapted to desert climates, where they are known to thermoregulate in response to temperature variations throughout the day (O’Neill et al. 1988, Morgan and Shelly 1988, O’Neill and Kemp 1990). Few species occur in woodland areas, and those that do tend to aggregate along the edges, near grasslands. In Florida, all four subfamilies of Asilidae (Asilinae, Dasypogoninae, Laphriinae, and Leptogastrinae) are present,. Within these subfamilies, the following genera are known to exist in Florida:

Description

Asilidae are a family of true flies belonging to the superfamily Asiloidea within the suborder Brachycera. To date, there are approximately 7,003 described species of Asilidae distributed throughout the world (Geller-Grimm 2008). There are nearly 1,000 North American species of robber flies, with more than 100 species occurring in Florida. Loew was perhaps the most influential dipterist to contribute information to the study of robber flies, describing several species and more than 80 genera. Other mid-nineteenth century contributors include Macquart, Walker, Rondani, and Bigot. Later, dipterists in the 1900’s became specialists of robber flies in particular locales, most notably Curran and Bromley in North America.

All robber flies have a characteristic divot on top of the head, which is located between their especially prominent compound eyes. In general, adult Asilidae have an elongate body with a tapered abdomen. However, some species are stout and hairy, mimicking bumble bees, and still others may be slender and have a damsel fly appearance. Adults range in size from small (3 mm) to very large (over 50 mm), averaging 9 to 15 mm in length (Wood 1981). Robber flies have long, strong legs that are bristled to aid in prey capture. Sexual dimorphisms are not extreme, although females tend to have slightly broader abdomens than males. Most robber flies have a brown, gray, or black coloration.

Biology

Female Asilidae deposit whitish-colored eggs on low-lying plants and grasses, or in crevices within soil, bark, or wood. Egg-laying habits depend on the species and their specific habitat; most species lay their eggs in masses, which are then covered with a chalky protective coating. Robber fly larvae live in the soil or in various other decaying organic materials that occur in their environment. Larvae are also predatory, feeding on eggs, larvae, or other soft-bodied insects. Robber flies overwinter as larvae and pupate in the soil. Pupae migrate to the soil surface and emerge as adults, often leaving behind their pupal casing. Complete development ranges from one to three years, depending on species and environmental conditions. Theodor (1980) proposed that larval growth is accelerated in warmer regions and that many Asilidae species live no longer than one year.

Behavior

Robber flies are opportunistic predators, their diets often reflecting prey availability in a particular habitat. Shelly (1986) reported that of the nine Neotropical Asilidae species he studied, diet constituents were more than 85% composed of insects from the orders Diptera, Coleoptera, Hymenoptera, Homoptera, and Lepidoptera. Furthermore, larger species tended to consume a greater diversity of prey taxa. Robber flies generally establish a perching zone in which to locate potential prey. Perching height varies by species, but generally occurs in open, sunny locations. Asilidae seize their prey in flight and inject their victims with saliva containing neurotoxic and proteolytic enzymes. This injection, inflicted by their modified mouthparts (hypotharynx), rapidly immobilizes prey and digests bodily contents. The robber fly soon has access to a liquid meal, which is generally consumed upon returning to a perched position.

Robber flies exhibit minimal courtship behavior. Instead, the male pounces on the female much like an act of prey acquisition. Copulation is accomplished in a tail-to-tail fashion with the male and female genetalia interlocked. Flight is not completely inhibited during mating.

Maggot


Maggot is the common name of the soft-bodied, legless, worm-like larva of insects of the order Diptera, typically with a reduced head, which may be retracted into the body. The term often is associated with larvae that live on decaying flesh or tissue debris of animals and plants, although there are some species that consume healthy animal tissue and many forms that consume living plant matter.

Many maggots have a reputation as plant pests, such as the apple maggot (Rhagoletis pomonella), the cabbage maggot (Delia radicum), the larvae form of the common crane fly (Tipula sp.), and other root maggots, midge maggots, and leaf miners. Some also are parasites of mammals, eating live flesh or burrowing under the skin to cause lesions or damage to organs. Humans and domestic animals can be infected and thus measures to prevent infestation are often recommended, such as proper garbage disposal.

However, maggots also provide many important functions in the ecosystem and for humans. Ecologically, they are important for the decomposition of dead tissues and in retaining nutrients, are vital to food chains, and some, such as the hover fly (Syrphus ribesii) consumes plant pests, such as aphids. Some maggots have commercial use, being sold as bait for fishing or food for pets. Some even have application in forensic science for determining time of death. Furthermore, certain species, particularly blowflies, have important medical applications, being used historically and currently for stimulating proper healing of wounds.

Overview and description

A true fly is any species of insect of the order Diptera. True flies undergo a complete metamorphosis, or complex metamorphosis, in which there are four distinct stages: Egg, larva, pupa, and adult. The larval phase of development is commonly known as a maggot. Depending on the species, there are generally 3 to 8 larval stages. Many species have larva in which the head is reduced and retracted into the body, with the much reduced head and mouthparts at the pointed end (Kendall 2007).

In the larval stage, the legless maggot generally begins to feed on whatever the egg was laid on, such as decomposing flesh. The maggot gorges itself with food until it is ready to enter the pupal stage, at which point the maggot travels away from the food source to an appropriate, generally moist spot. During the pupal stage, it metamorphosizes into an adult. Maggots tend to be voracious feeders.

Importance of maggots

Ecological, commercial, and forensic

Ecological functions. Maggots are important as decomposers, helping to break down decaying tissues and retaining the nutrients, rather than being lost. The flesh of dead animals are quickly reduced by maggots. Furthermore, maggots are important in food chains, being consumed by a wide variety of invertebrates and vertebrates. The hover fly (Syrphus ribesii), which is an important pollinator in the adult stage, also has a helpful larval stage, as the maggots are active predators of aphids and other plant-sucking insects and thus are natural enemies of plant pests (Kendall 2007).

Commercial functions. Maggots are bred commercially, as a popular bait in fishing, and a food for carnivorous pets such as reptiles or birds. Maggots have been used in food production, particularly cheese.

Forensic science. Some types of maggots found on corpses can be of great use to forensic scientists. By their stage of development (instar), these maggots can be used to give an indication of the time elapsed since death, as well as the place the organism died.

Maggot therapy

Certain live maggots have been employed since antiquity as an economical, safe and effective type of wound debridement (cleaning). Long ago, including during the U.S. Civil War and World War I, some doctors noticed soldiers that had maggots on their wounds healed quicker than those without maggots. Maggot Therapy (also known as Maggot Debridement Therapy (MDT), larval therapy, larva therapy, or larvae therapy) is the intentional introduction of live, disinfected maggots or fly larvae into non-healing skin or soft tissue wounds of a human or other animal. This practice was widely used before the discovery of antibiotics, as it serves to clean the dead tissue within a wound in order to promote healing. While maggot therapy declined with the advent of antibiotics and surgical techniques, there has been renewed interest in recent years.

Today, in controlled and sterile settings by licensed medical practitioners, maggot therapy introduces live, disinfected maggots into non-healing skin or soft wounds of a human or other animal. The maggots consume the dead tissue and skin, leaving the live tissue alone, while excreting powerful antibiotics to which bacteria have not yet developed tolerance, thus killing the bacteria or inhibiting their growth. As of 2008, maggot therapy was being used in around 1000 medical centers in Europe and over 300 medical centers in the United States (Ngan 2008).

Only a few species of fly larvae are suitable for such use in maggot therapy, notably blowflies (Handwerk 2003). Maggots of the blowfly have been used to treat injuries like pressure ulcers (bed sores), stab wounds, leg and foot ulcers, and post-surgical wounds that are not healing properly (Willis 2001).

Deleterious actions

Diverse maggots cause damage in agricultural crop production, including root maggots in rapeseed and midge maggots in wheat. Some maggots are leaf miners. The apple maggot (Rhagoletis pomonella), also known as railroad worm, is a pest of several fruits, mainly apples. The cabbage maggot (Delia radicum), also known as the root maggot, is a known pest to crops as well. The white eggs, which are about one millimeter in diameter, hatch into while maggots after about six days and the larvae feed for about three weeks on the roots and stems of the cabbage plants. The common crane fly (Tipula sp.) has larvae known as “leatherjackets” that can be a serious threat to farm and garden crops, as well as grassland and lawns, as the maggots live in the soil and feed on plant roots (Kendall 2007).

While maggots of most fly species only eat necrotic tissue in living animals and are thus arguably symbiotic, certain types of maggots are parasitic, such as botfly larvae, which spend part of their life cycle as parasites under the skin of living animals. As with fleas and ticks, parasitic maggots can be a threat to household pets and livestock, especially sheep. Flies reproduce rapidly in the summer months and maggots can come in large numbers, creating a maggot infestation and a high risk of myiasis in sheep and other animals. Myasis is the infection of an animal with maggots. While the myiasis of some species is beneficial in terms of maggot therapy, other species attracted to wounds can be harmful. They may burrow into the skin and cause lesions or move through the body and cause organ damage (Willis 2001).

The larva of various species of the screw worm fly are unusual in that they attack live flesh as well as decaying flesh. The screw worm fly, which is an obligatory parasite of mammals, including humans, sometimes is referred to as a “flesh-eater.” It lays its eggs on the edges of wounds or in mucous membranes of body openings and the larva burrow downwards into the tissue, causing extensive tissue damage and sometimes death. The United States was able to wipe out most populations of this fly by using sterile males to result in eggs that did not hatch (Willis 2001).

Humans are not immune to the feeding habits of maggots and can also contract myiasis. Interaction between humans and maggots usually occurs near garbage cans, dead animals, rotten food, and other breeding grounds for maggots.

A major problem also arises when maggots turn into flies and start the life cycle over again. Within a few generations the number of maggots grows exponentially and becomes a serious problem. Professionals can remove maggots or many over-the-counter bug sprays can be used to deter flies and maggots. Keeping trash in a sealed container and using a garbage disposal or freezing rotting leftovers until rubbish collection day helps prevent infestation.

 

Flesh-fly


Flies of the Diptera family Sarcophagidae (from the Greek sarco- = flesh, phage = eating; the same roots as the word “sarcophagus”) are commonly known as flesh flies. Most flesh flies breed in carrion, dung, or decaying material, but a few species lay their eggs in the open wounds of mammals; hence their common name. Some flesh fly larvae are internal parasites of other insects. These larvae, commonly known as maggots, live for about 5–10 days, before descending into the soil and maturing into adulthood. At that stage, they live for 5–7 days.

Characteristics

Antennae 3-segmented, with an arista; vein Rs 2-branched, frontal suture present, calypters well developed. Medium-sized flies with black and gray longitudinal stripes on the thorax and checkering on the abdomen. Arista commonly plumose on basal half; bare in a few species. Four notopleural bristles (short, long, short, long, from front to rear). Hindmost posthumeral bristle located even with or toward midline from presutural bristle.

The family contains three subfamilies, the Miltogramminae, the Paramacronychiinae and the Sarcophaginae, containing between them 108 genera. Flesh-flies are quite closely related to the family Calliphoridae, which belongs to the same (large) infraorder, the Muscomorpha, and includes species such as the blowfly that have similar habits to the flesh-flies.

Biology

Flesh-fly maggots occasionally eat other larvae although this is usually because the other larvae are smaller and get in the way. Flesh-flies and their larvae are also known to eat decaying vegetable matter and excrement and they may be found around compost piles and pit latrines.

Flesh-flies, being viviparous, frequently give birth to live young on corpses of human and other animals, at any stage of decomposition from recently dead through to bloated or decaying (though the latter is more common).

The life cycle of flesh-fly larvae has been well researched and is very predictable. Different species prefer bodies in different states of decomposition, and the specific preferences and predictable life cycle timings allows forensic entomologists to understand the progress of decomposition and enables the calculation of the time of death by back extrapolation. This is done by determining the oldest larva of each species present, measuring the ambient temperature and from these values, calculating the earliest possible date and time for deposition of larvae. This yields an approximate time and date of death (d.o.d.) This evidence can be used in forensic entomology investigations and may assist in identification of a corpse by matching the calculated time of death with reports of missing persons. Such evidence has also been used to help identify murderers.

Association with disease

Flesh-flies can carry leprosy bacilli and can transmit intestinal pseudomyiasis to people who eat the flesh-fly larvae. Flesh-flies, particularly Wohlfahrtia magnifica, can also cause myiasis in animals, mostly to sheep, and can give them blood poisoning, or asymptomatic leprosy infections.

 

Queen Alexandra’s Birdwing


Queen Alexandra’s Birdwing (Ornithoptera alexandrae) is the largest butterfly in the world.

The species was named by Lord Walter Rothschild in 1907, in honour of Queen Alexandra, wife of King Edward VII of the United Kingdom. The first European to discover the species was Albert Stewart Meek in 1906, a collector employed by Lord Walter Rothschild to collect natural history specimens from Papua New Guinea. Although the first specimen was taken with the aid of a small shotgun, Meek soon discovered the early stages and bred out most of the first specimens. It is restricted to the forests of Oro Province in eastern Papua New Guinea.

Though most authorities now classify this species in the genus Ornithoptera, it has formerly been placed in the genus Troides or Aethoptera. In 2001 the lepidopterist Gilles Deslisle proposed placing it in its own subgenus (which some writers have treated as a genus); he originally proposed the name Zeunera, but this is a junior homonym (with Zeunera Piton 1936 [Orthoptera]), and his replacement is Straatmana.

Description

Female Queen Alexandra’s Birdwings are larger than males with markedly rounder, broader wings. The female can reach a wingspan of 31 cm (>12 inches), a body length of 8 cm (3.2 inches) and a body mass of up to 12 grams (0.42 oz), all enormous measurements for a butterfly. The female has brown wings with white markings and a cream-coloured body with a small section of red fur on its thorax. Males are smaller than females with brown wings that have iridescent blue and green markings and a bright yellow abdomen. The wingspan of the males is approximately 20 cm, but more usually about 16 cm. A spectacular form of the male is form atavus, which has gold spots on the hind wings.

Host plants

Larvae of this species feed on pipe vines of the genus Pararistolochia (family Aristolochiaceae), including P. dielsiana and P. schlecteri. They feed initially on fresh foliage of the hostplants and ultimately ringbark the vine before pupating. Plants of the Aristolochiaceae family contain aristoloic acids in their leaves and stems. This is believed to be a potent vertebrate poison and is accumulated by larvae during their development. Adults feed at flowers providing a broad platform for the adults to land on, including Hibiscus.

Biology

The female Queen Alexandra’s Birdwing lays about 27 eggs during its entire lifespan; this estimate was made by Ray Straatman by dissecting adult females. Newly emerged larvae eat their own eggshells before feeding on fresh foliage. The larva is black with red tubercles and has a cream-colored band or saddle in the middle of its body. The larvae always ringbark the host vine before moving onto adjacent leaves or vines to become a pupa, which is golden yellow or tan in colour with black markings. Male pupae may be distinguished by a faint charcoal patch on the wing cases; this becomes a band of special scales in the adult butterfly called a sex brand. The time taken for this species to develop from egg to pupa is approximately six weeks, with the pupal stage taking a month or more. Adults emerge from the pupae early in the morning while humidity is still high, as the enormous wings may dry out before they have fully expanded if the humidity drops. The adults may live for three months or more and have few predators, excluding large Orb Weaving spiders (Nephila spp.) and some small birds.

The adults are powerful fliers most active in the early morning and again at dusk when they actively feed at flowers. Males also patrol areas of the host plants for newly emerged females early in the morning. Females may be seen searching for host plants for most of the day. Courtship is brief but spectacular; males hover above a potential mate, dousing her with a pheromone to induce mating. Receptive females will allow the male to land and pair, while unreceptive females will fly off or otherwise discourage mating. Males are strongly territorial and will see off potential rivals, sometimes chasing small birds as well as other birdwing species. Flight is usually high in the rainforest canopy, but both sexes descend to within a few meters of the ground while feeding or laying blue eggs.

Threats

The Queen Alexandra’s Birdwing is considered endangered by the IUCN, being restricted to approximately 100 square kilometres of coastal rainforest near Popondetta, Oro Province, Papua New Guinea. It is nonetheless abundant locally and requires old growth rainforest for its long term survival. The major threat for this species is habitat destruction for oil palm plantations. However, it must be noted that the eruption of nearby Mount Lamington in the 1950s destroyed a very large area of this species’ former habitat and is a key reason for its current rarity. Because of its rarity, this butterfly fetches a very high price on the black market.

The species is also highly prized by collectors, with illegally traded specimens selling for thousands of dollars. Although collectors are often implicated with the decline of this species, habitat destruction is the main threat. Early collectors, frustrated by the height at which adults fly during the day, often used small shotguns to down specimens. but because collectors demand high quality specimens for their collections, most specimens are reared from larvae or pupae.

The species is listed on Appendix I of CITES, meaning that international trade is illegal. At the 2006 meeting of the CITES Animals Committee some suggested it should be moved to Appendix II (which would allow restricted trade in the species), as the conservation benefits of sustainable management perhaps are higher than those of the trade ban.

 

Opiliones


Harvestmen is the common name for any of the eight-legged invertebrate animals comprising the order Opiliones (formerly Phalangida) in the arthropod class Arachnida, characterized by a body in which the two main sections, the cephalothorax and abdomen, are broadly joined so that they appear as if one oval structure. Commonly they also have long walking legs, which has led to them being known in some places as daddy longlegs or grandaddy longlegs. Although they belong to the class of arachnids, harvestmen are not spiders, which are of the order Araneae rather than the order Opiliones. There are over 6,000 species of opiliones.

Found in terrestrial habitats worldwide, on all continents except for Antarctica, harvestmen play important ecological roles as part of food chains. Mostly omnivorous, consuming invertebrates (insects, snails, and so on), plant matter, fungi, and carrion, they serve as food for birds, spiders, frogs, toads, and other organisms. For human beings, they add to the diversity of nature. However, despite their importance and diversity—they are the third largest order of arachnids, after Acari (mites and ticks) and Araneae (spiders)—they remain poorly studied.

Harvestmen also reflect the tendency of species to demonstrate stasis once they come into existence: Fossils 400 million years old have been found that look like modern harvestmen, reflecting the slight changes in basic structure over that time.

Overview and description

 

Harvestment or opiliones comprise the order Opiliones in the class Arachnida in the subphylum Chelicerata of the phylum Arthropoda. Arachnida is a largely terrestrial group that also includes spiders, mites, ticks, and scorpions. Arachnids are characterized by four pairs of segmented walking legs and a body divided into two regions, the cephalothorax and the abdomen, the cephalothorax being derived from the fusion of the cephalon (head) and the thorax.

Harvestmen are known for their exceptionally long walking legs, compared to body size, although there are also short-legged species. The difference between harvestmen and spiders is that in harvestmen the two main body sections (the abdomen with ten segments and the cephalothorax—or the prosoma and opisthosoma) are broadly joined, so that they appear to be one oval structure; they also have no venom or silk glands. In more advanced species of harvestment, the first five abdominal segments are often fused into a dorsal shield called the scutum, which is normally fused with the carapace. Sometimes this shield is only present in males. The two most posterior abdominal segments can be reduced or separated in the middle on the surface to form two plates lying next to each other. The second pair of legs are longer than the others and work as antennae. This can be hard to see in short-legged species.

Typical body length does not exceed 7 millimeters (about 5/16 inch), with some species smaller than one millimeter, although the largest species Trogulus torosus (Trogulidae) can reach a length of 22 millimeters (Pinto-da-Rocha et al. 2007). However, leg span is much larger and can exceed 160 millimeters (over 6 inches).

The feeding apparatus (stomotheca) differs from other arachnids in that ingestion is not restricted to liquid, but chunks of food can be taken in. The stomotheca is formed by extensions from the pedipalps and the first pair of legs.

Harvestmen have a single pair of eyes in the middle of their heads, oriented sideways. However, there are eyeless species (for example the Brazilian Caecobunus termitarum (Grassatores) from termite nests, Giupponia chagasi (Gonyleptidae) from caves, and all species of Guasiniidae) (Pinto-da-Rocha and Kury 2003).

 

Harvestmen have a pair of prosomatic defensive scent glands (ozopores) that secrete a peculiar smelling fluid when disturbed, confirmed in some species to contain noxious quinones. Harvestmen do not have silk glands and do not possess venom glands, posing absolutely no danger to humans .

Harvestmen do not have book lungs, and breathe through tracheae only. Between the base of the fourth pair of legs and the abdomen a pair of spiracles are located, one opening on each side. (Spiracles are small openings on the surface that lead to the respiratory system.) In more active species, spiracles are also found upon the tibia of the legs.

Harvestmen have a gonopore on the ventral cephalothorax, and copulation is direct as the male has a penis (while the female has an ovipositor). All species lay eggs. Most species live for a year.

The legs continue to twitch after they are detached. This is because there are “pacemakers” located in the ends of the first long segment (femur) of their legs. These pacemakers send signals via the nerves to the muscles to extend the leg and then the leg relaxes between signals. While some harvestman’s legs will twitch for a minute, other kinds have been recorded to twitch for up to an hour. The twitching has been hypothesized as a means to keep the attention of a predator while the harvestman escapes (Pinto-da-Rocha et al. 2007).

The former scientific name for Opiliones was Phalangida and this name still often appears in the literature. The common name “daddy longlegs” also is used for the crane fly (Tipulidae) and the cellar spider (Pholcidae) (Crawford 2005).

Behavior, diet, and reproduction

 

Many species of harvestmen are omnivorous, eating primarily small insects and all kinds of plant material and fungi; some are scavengers, feeding upon dead organisms, bird dung, and other fecal material. This broad range is quite unusual in arachnids, which are usually pure predators. Most hunting harvestmen ambush their prey, although active hunting is also found. Because their eyes cannot form images, they use their second pair of legs as antennae to explore their environment. Also unlike most other arachnids, harvestmen do not have a sucking stomach and a filtering mechanism, but ingest small particles of their food, thus making them vulnerable to internal parasites, such as gregarines (Pinto-da-Rocha et al. 2007).

Although parthenogenetic species do occur, most harvestmen reproduce sexually. Mating involves direct copulation, rather than the deposition of a spermatophore. The males of some species offer a secretion from their chelicerae to the female before copulation. Sometimes the male guards the female after copulation, and in many species the males defend territories.

The females lay eggs shortly after mating, or up to months later. Some species build nests for this purpose. A unique feature of harvestmen is that in some species the male is solely responsible for guarding the eggs resulting from multiple partners, often against egg-eating females, and subjecting the eggs to regular cleaning. The eggs can hatch anytime after the first 20 days, up to almost half a year after being laid. Harvestmen need from four to eight nymphal stages to reach maturity, with six the most common (Pinto-da-Rocha et al. 2007).

Harvestmen are mostly nocturnal and colored in hues of brown, although there are a number of diurnal species that have vivid patterns in yellow, green, and black with varied reddish and blackish mottling and reticulation.

To deal with predators such as birds, mammals, amphibians, and spiders, some species glue debris onto their body, and many play dead when disturbed. Many species can detach their legs, which keep on moving to confuse predators. Very long-legged species vibrate their body (“bobbing”), probably also to confuse. This is similar to the behavior of the similar looking but unrelated daddy longlegs spider, which vibrates wildly in its web when touched. Scent glands emit substances that can deter larger predators, but are also effective against ants (Pinto-da-Rocha et al. 2007).

Many species of harvestmen easily tolerate members of their own species, with aggregations of many individuals often found at protected sites near water. These aggregations can count up to 200 animals in the Laniatores, but more than 70,000 in certain Eupnoi. This behavior may be a strategy against climatic odds, but also against predators, combining the effect of scent secretions, and reducing the probability of each individual of being eaten (Pinto-da-Rocha et al. 2007).

Endangered status

Some troglobitic (cave dwelling) Opiliones are considered endangered if their home caves are in or near cities where pollution and development of the land can alter the cave habitat. Others species are threatened by the invasion of non-native fire ants.

All troglobitic species (of all animal taxa) are considered to be at least threatened in Brazil. There are four species of Opiliones in the Brazilian National List for endangered species, all of them cave-dwelling species. Giupponia chagasi (Pérez & Kury, 2002, Iandumoema uai Pinto-da-Rocha, 1996, Pachylospeleus strinatii Šilhavý, 1974, and Spaeleoleptes spaeleus H. Soares, 1966).

Several opiliones in Argentina appear to be vulnerable, if not endangered. These include Pachyloidellus fulvigranulatus (Mello-Leitão, 1930), which is found only on top of Cerro Uritorco, the highest peak in the Sierras Chicas chain (provincia de Cordoba), and Pachyloides borellii (Roewer, 1925) is in rainforest patches in North West Argentina, which are in an area being dramatically altered by humans. The cave living Picunchenops spelaeus (Maury, 1988) is apparently endangered through human action. So far no harvestman has been included in any kind of a Red List in Argentina and therefore they receive no protection.

Maiorerus randoi (Rambla, 1993) has only been found in one cave in the Canary Islands. It is included in the Catálogo Nacional de especies amenazadas (National catalog of threatened species) from the Spanish government.

Texella reddelli (Goodnight & Goodnight, 1967) and Texella reyesi (Ubick & Briggs, 1992) are listed as endangered species in the United States. Both are from caves in central Texas. Texella cokendolpheri (Ubick & Briggs, 1992) from a cave in central Texas and Calicina minor (Briggs & Hom, 1966), Microcina edgewoodensis (Briggs & Ubick, 1989), Microcina homi (Briggs & Ubick, 1989), Microcina jungi (Briggs & Ubick, 1989), Microcina leei Briggs & Ubick 1989, Microcina lumi (Briggs & Ubick, 1989), and Microcina tiburona (Briggs & Hom, 1966) from around springs and other restricted habitats of central California are being considered for listing as endangered species, but as yet receive no protection.

Misconception

An urban legend claims that the harvestman is the most venomous animal in the world, but possesses fangs too short or a mouth too round and small to bite a human and therefore is not dangerous (Crawford 2005). (The same myth applies to the cellar spider, which is also called a daddy longlegs.) This is untrue on several counts. None of the known species have venom glands or fangs, instead having chelicerae (OIDG 2005). The size of its mouth varies by species, but even those with relatively large jaws hardly ever bite humans or other large creatures, even in self-defense.

Research

Harvestmen are a scientifically much neglected group. Description of new taxa has always been dependent on the activity of a few dedicated taxonomists. Carl Friedrich Roewer described about a third (2,260) of today’s known species from the 1910s to the 1950s, and published the landmark systematic work Die Weberknechte der Erde (Harvestmen of the World) in 1923, with descriptions of all species known to that time. Other important taxonomists in this field include Eugène Simon, Tord Tamerlan Teodor Thorell, William Sørensen, and Zac Jewell around the turn of the twentieth century, and later Cândido Firmino de Mello-Leitão and Reginald Frederick Lawrence. Since 1980, study of the biology and ecology of harvestmen has intensified, especially in South America (Pinto-da-Rocha et al. 2007).

Phylogeny and systematics

Harvestmen are very old arachnids. Fossils from the Devonian, 400 million years ago, already show characteristics like tracheae and sexual organs, proving that the group has lived on land since that time. They are probably closely related to the scorpions, pseudoscorpions, and solifuges; these four orders form the clade Domopod. The Opiliones have remained almost unchanged morphologically over a long period (Pinto-da-Rocha et al. 2007). Well-preserved fossils have been found in the 400-million year old Rhynie cherts of Scotland, which look surprisingly modern, indicating that the basic structure of the harvestmen has not changed much since then.

As of 2006, over 6,400 species of harvestmen have been discovered worldwide, although the real number of extant species may exceed 10,000 (Pinto-da-Rocha et al. 2007). The order Opiliones can be divided in four suborders: Cyphophthalmi (Simon, 1879), Eupnoi (Hansen & Sørensen, 1904), Dyspnoi (Hansen & Sørensen, 1904), and Laniatores (Thorell, 1876). Cyphophthalmi are one of the two lineages of harvestmen; the other, containing the Laniatores, Dyspnoi and Eupnoi, is also called Phalangida.

Relationship within suborders

Cyphophthalmi

The Cyphophthalmi have been divided into two infraorders, Temperophthalmi (including the superfamily Sironoidea, with the families Sironidae, Troglosironidae, and Pettalidae) and Tropicophthalmi (with the superfamilies Stylocelloidea and its single family Stylocellidae, and Ogoveoidea, including Ogoveidae and Neogoveidae). However, recent studies suggest that the Sironidae, Neogoveidae, and Ogoveidae are not monophyletic, while the Pettalidae and Stylocellidae are. The division into Temperophthalmi and Tropicophthalmi is not supported, with Troglosironidae and Neogoveidae probably forming a monophyletic group. The Pettalidae are possibly the sister group to all other Cyphophthalmi.

While most Cyphophthalmi are blind, eyes do occur in several groups. Many Stylocellidae, and some Pettalidae bear eyes near or on the ozophores, as opposed to most harvestmen, which have eyes located on top. The eyes of Stylocellidae could have evolved from the lateral eyes of other arachnids, which have been lost in all other harvestmen. Regardless of their origin, it is thought that eyes were lost several times in Cyphophthalmi. Spermatophores, which normally do not occur in harvestmen, but in several other arachnids, are present in some Sironidae and Stylocellidae (Giribet and Kury 2007).

Eupnoi

 

The Eupnoi are currently divided into two superfamilies, the Caddoidea and Phalangioidea. The Phalangioidea are assumed to be monophyletic, although only the families Phalangiidae and Sclerosomatidae have been studied; the Caddoidea have not been studied at all in this regard. The limits of families and subfamilies in Eupnoi are uncertain in many cases, and are in urgent need of further study (Giribet and Kury 2007).

Dyspnoi

The Dyspnoi are probably the best studied harvestman group regarding phylogeny. They are considered to be clearly monophyletic, and divided into two superfamilies. The relationship of the superfamily Ischyropsalidoidea, comprised of the families Ceratolasmatidae, Ischyropsalididae, and Sabaconidae, has been investigated in detail. It is not clear whether Ceratolasmatidae and Sabaconidae are each monophyletic, as the ceratolasmatid Hesperonemastoma groups with the sabaconid Taracus in molecular analyses. All other families are grouped under Troguloidea (Giribet and Kury 2007).

Laniatores

 

There is not yet a proposed phylogeny for the whole group of Laniatores, although some families have been researched in this regard. The Laniatores are currently divided into two infraorders, the “Insidiatores” (Loman, 1900) and the Grassatores (Kury, 2002). However, Insidiatores is probably paraphyletic. It consists of the two superfamilies Travunioidea and Triaenonychoidea, with the latter closer to the Grassatores. Alternatively, the Pentanychidae, which currently reside in Travunioidea, could be the sister group to all other Laniatores.

The Grassatores are traditionally divided into the Samooidea, Assamioidea, Gonyleptoidea, Phalangodoidea, and Zalmoxoidea. Several of these groups are not monophyletic. Molecular analyses relying on nuclear ribosomal genes support monophyly of Gonyleptidae, Cosmetidae (both Gonyleptoidea), Stygnopsidae (currently Assamioidea), and Phalangodidae. The Phalangodidae and Oncopodidae may not form a monophyletic group, thus rendering the Phalangodoidea obsolete. The families of the obsolete Assamioidea have been moved to other groups: Assamiidae and Stygnopsidae are now Gonyleptoidea, Epedanidae reside within their own superfamily Epedanoidea, and the “Pyramidopidae” are possibly related to Phalangodidae (Giribet and Kury 2007).

The family Stygophalangiidae (1 species, Stygophalangium karamani) from underground waters in Macedonia is sometimes misplaced in the Phalangioidea. It is not a harvestman.