"Odd insects"-Mistaken identity, cannibals, and widows: Do You Know?
Arachnids.Order Arachnida. Spiders.Scorpions. Mites. Ticks.Chelicerae. Pedipalp. Book Lungs. Trichobothria. Gonophore. Cannibalism. Parasitic. Diseases. Arachnophobia. Arachnomancy. Selket. Arachne.
You're feeling good with a cup of coffee in your hand, sitting in the porch, appreciating the ambience of green lawn, you proceeded to open the morning newspaper, but you skip the front page and go the Horoscope section, voila! Scorpio (24 Oct.- 22 Nov.)-loyal, passionate, resourceful, observant, and dynamic but you are also jealous, obsessive, suspicious, manipulative, and unyielding. A great constellation of stars saw in the early morning dawn, Scorpius. Mom screamed in the kitchen, terrifying sounds as she saw something black crawling in the sink with cobwebs in the window pane and something nimbly crawl away on the floor. Spiders are coming! Fear of spiders-Arachnophobia.
Feared and revered at the same time, these creatures are called Arachnids-Spiders, Scorpions, Ticks, Mites, and Allies belongs to the great Taxon sub-Phylum Chelicerata, Order-Arachnida. Mistakenly called Insects and Widows are misnomers for they are a distinct group of invertebrates in the Animal Kingdom. Considered as ancient in their evolutionary history, as fossil evidence revealed that their ancient ancestors were already present during the extant Carboniferous Period, are a group of diverse organisms of about one million species. The Arachnids have occupied every nook and crevices of the planet Earth, except Antartica. Arachnids are a distinct taxonomic group from the Order Insecta, for instance, Arachnids have four pairs of legs while insects have three pairs of legs only. Normally nocturnal in their feeding habits while most insects are diurnal, Some microscopic Arachnids ((Mites and Ticks) may feed on fungal spores, nematodes, the blood of animals including humans, otherwise, they prefer insects, arachnids, and small mammals. Through evolution, some are parasitic, and vectors of plants, animals, and humans diseases. Other Arachnids produce venom as a defense mechanism, however, are detrimental to humans. Unless provoke, Arachnids are shy and docile organisms.
Though feared and terrifying Arachnids have inspired human civilization past and present In Classical Greece, Spider and Scorpion were found in their legends and myths, revered and worshiped as gods in ancient Egypt, the unsolved mystery of the Spider Glyph at Nazca, Peru, and in religious and folklore practices of native American Indians. Arachnids are also depicted in works of arts and culture, in Agriculture and Gardens for the control of insects pests, they are considered as nature's pesticides, raised as pets(eg.Tarantula) and lately scientist are interested in spider silks for military armor, garments from spider silks and in tissue engineering, spider silk as material for peripheral nerve re-growth(Wikipedia, the free Encyclopedia). Conversely, the art and practice of divining future events by interpreting the symbolic patterns resulting from the behavior of Spiders is called Arachnomancy. Now, what make these "insects" Odds? Let us discover it together.
Geography, Distribution, and Ecology
According to Codington and Colwell (2001), the known diversity of Arachnids is approximately 640 families, 9,000 genera, and 93,000 species, but there are thousands of new mites and spiders still undescribed and hundred to thousands of undescribed species in the remaining order. Arachnids ancient ancestors was found as early as the Silurian Period of the Paleozoic Era and onto lands shortly before the insects appeared in the middle Devonian Period about 385 million years ago and on the next millions of years both groups radiated into distinct lineages. By 354 to 290 million years of the Carboniferous Period, while the main groups of modern Arachnids, Mygalomorphae and Aranaomorhae first appeared in the Triassic Period before 200 million years ago.
Arachnids are among the successful invertebrates of the Animal Kingdom. Arachnids along with insects are by far the most species-rich, abundant, and widely distributed terrestrial Arthropods. Acarologists (scientist who study mites and ticks) estimated that the total extant diversity of mites and ticks to the tune of one million species. Arachnids are important components of every Terrestrial Ecosystem, apart from several specialized Mite lineages none is aquatic or marine. Most are predators, some are venomous, and still others are parasitic and vector of plants, animal, and human diseases.
Ancient history,legends and myths, cultures and beliefs, and folklore's of Arachnids
Man's history has been imbued with legends and myths that interspersed in their culture and beliefs. Through time these stories and legends were passed from generations to generations through village historians, elders and parents on tales about creation, explanation about the meaning of life and stories of gods and monsters that once ruled the earth and the heavens.
Egyptian goddess Selket or Serlket.
- Serket- the Egyptian Scorpion goddess of magic protection and healing. he famous symbol of Selket is the Scorpion (Headdress) an insect that was numerous in the desert regions of ancient Egypt.
- The Scorpion symbolized death and were believed to be taken by the restless dead. Scorpion amulets depicting Selket as protection against Scorpion sting.
- Selket was also the powerful protector of Quebehsanuet, the Canopic god guarding the intestine of the dead.
Ancient Greece the legend of Arachne, the Spider
- According to the Greek legend, Spiders were created when the seamstress named Arachne challenged the goddess Athena to a contest.
- The story further that Arachne was defeated and because of her prideful actions she became ashamed and she hung herself with the thread she used in weaving.
- Athena felt sorry for her and brought her back to life as a spider and her yarn was made into the web. Her name was also used by the scientist who studied Spiders- Arachnologist, the fear of Spiders- Arachnophobia and the class of animals called Arachnida (Arachnids).
Greek myth-Constellation Scorpio or Scorpius
- When the earth goddess Gaia, learned Orion's (the great hunter) plan to kill all the beast on Earth, Gaia was angry and created a giant Scorpion to hunt Orion.
- Eventually, Orion was killed by Scorpion sting, but Zeus, the final arbiter recognized their courage and prowess in battle, transformed the two rivals into a star very far from each other 180ο in the sky never to meet again.That is why Scorpion or Scorpius is seen at the morning dawn while Orion is seen at sunset.
- Scorpius or Scorpion is the 8th sign of the Zodiac Horoscope
Cultures, Beliefs, and Folklore's about Spiders
Spiders have been used in human culture to represent many varied things that endure into the present day from the fantasy movie of Harry Potter and Spider-man, the eponymous comics strips, to Horoscope, the Spider has symbolized patience and persistence due to its hunting techniques of setting webs and waiting for its prey to become ensnared. it is also a symbol of mischief and malice for it's toxic venom and slow death it causes which is often associated wth a curse.For example:
- In the Global setting, the Internet, a World Wide Web evoked the sites connectivity to a spider web.
- Philosophers often use the Spiderweb as a metaphor in analogy in today's terms such as the Internet
- The Spider God Temple in Peru.The spider deity was associated with life-giving rain, textile, hunting, war, and power and the mystery of the Spider Glyph at Nazca.
- Spider image in Patia shell gorget by the Stone Grave people, Faint's Island, Tennessee.
- Ancient Moche people of Peru depict Spiders in their art- Ceramics (300 CE )
- Tale of Tsuchigumo (translated as an early spider) of Japan, is the mythical, supernatural creature faced by the legendary Minamoto no Raiko.
- In Literature-Arachne in Dante's Divine Comedy-Porgatorio.
- Famous films/movies- Giant Spider- Aragog in the fantasy movie Harry Potter and the Chamber of Secrets. Shelob- the Giant Spider in the film Lord of the Rings Trilogy.
- Arachnomancy the art and practice of divining future events by interpreting the symbolic patterns resulting from the behavior of spiders.
- Spider tattoo is a culture among young generation
TAXONOMIC GROUP-EXAMPLE(S)/SPECIES NO.
- Amblypygi- Tailless Whip Scorpion (140 sp.)
- Araneae- True Spiders-Tarantula, Black Widow, etc. (40,000 sp.)
- Opiliones- Daddy long-legs/ Harvestman (6,300 sp.)
- Palpigradi- Microwhip Scorpion (80 sp.)
- Pseudoscorpionida- PseudoScorpion (3,000 sp.)
- Ricinulei- Hooded tick Spider (60 sp.)
- Schizomida- Whip Scorpion (220 sp.)
- Scorpiones- Scorpion (2,000 sp.)
- Solifuge- Sun Spider/Camel Spider (9,000 sp.)
- Thelyphonida- Vinegaroons/Vinegar Whip Scorpion (100 sp.)
- Acari- Mites and Ticks (30,000 sp.)
(Source: Wikipedia, the free Encyclopedia)
General characteristics of Arachnids
Together with marine horseshoe crabs (Xiphosura )and sea spiders (Pycnogonida ), Arachnids comprise the sub-Phylum Chelicerata, named for their characteristic pairs of pre-oral appendages, the Chelate or pinching mouth parts. In some Arachnid groups, the Chelicerae are further modified into venomous fangs or piercing stylets to suck body fluids in plants, animals, and humans (Codington and Colwell,2001).
Although erroneously mistaken to some sort of insects, Arachnids are quite distinct and distantly related to insects, In other words, Arachnids and Insects don't share the same ancestral lineages (Ibid). Most Arachnids and Insects may differ in Anatomy, Locomotion, Physiology and Digestive system (Wikipedia, the free Encyclopedia) among others.
- Anatomy. Arachnids have four pairs of legs while Insects three pairs of legs only.
- Major body parts are divided into two parts (head and abdomen ), while Insects, three body parts ( head, thorax, and Abdomen ).
- Lacking antennae, wings, and compound eyes found in insects
- Simpler mouth parts (Chelate )compared to more complex mouthparts of insects
- In many groups, the first pair of walking legs are elongated and function in such the same way as insect antennae (eg. Amblypygids, Uropygids, Solifugids, Palpigids, and many Mites)
To solve the challenges of terrestrial existence ( support, breathing, water balance, reproduction, and waste management) in many ways:
- Locomotion. Arachnids skeleton is hydraulic. Arachnids except Scorpions and Pseudoscorpions lack extensor muscle at key joints, instead the animal pump blood into the limbs to extend it.
- Solifuges and Harvestmen extend their knees by the use of highly elastic thickening in the joint cuticle.
- Scorpions, Pseudoscorpions, and some Harvestmen have evolved muscle that extend two leg joints (the femur- patella and patella- tibia joints ) at once.
Physiology. For gas exchange, Arachnids uses two or four pairs of Book lungs (gas-permeable gill-like membranes with blood on one side and open to air on the other side) to exchange carbon dioxide for oxygen rather than trachea, common among insects.
- Unlike insect trachea, Arachnid trachea generally does not ramify throughout the entire body or penetrate the inside body cells, ventilation is passive unlike insects is active.
- For this reason, Insect's trachea is more efficient in gas exchange than Arachnids. therefore, Insects can have a very intensive lifestyle than Arachnids.
- Spiders have significantly lower metabolic rates than other terrestrial Arthropods, for example, some Spiders (eg, Tarantula ) can survive for one month without food.
- Except for venomous Black Widow and Brown Recluse spiders, some species of Scorpions, parasitic Mites and Ticks, Arachnids, in general, are harmless, shy and docile creatures
Digestive system. Arachnids produce digestive juices in their stomach and use their pedipalps and chelicerae to pour them over their dead prey.
- Digestive juices rapidly turn the prey into a broth of nutrients which the Arachnids sucks into a pre-buccal cavity located immediately in front of the mouth.
- Behind the mouth is a muscular sclerotised pharynx wich acts like a pump, sucking the food to the mouth and into the oesophagus and stomach.
- The oesophagus also acts as an additional pump. In other words, digestion of food in Arachnids is done externally.
Vision, Hearing, and Tactile Response
Arachnids have two sets of simple eyes, the lateral and the median occulli.The lateral ocelli evolved from compound eyes (common among insects) and may have tapetum which enhances the ability to collect light.
- Arachnids are not really good for vision but rather rely on the movement that cause vibration. The most important to Arachnids are the fine sensory hairs that covered the body that gives the animal sense of touch.
- The other is the Slit Sense Organ. a slit-like pits covered with membranes. inside the pit, a small hair touches the underside of the membrane and detect motion, The slit sense organs is involved in the perception and possibly for hearing.
- To further compensate for poor eyesight, Arachnids posses Trichobothria (sing. Trichobothrium) that function in the detection of airborne vibrations and air currents. This attribute is very crucial in night time feeding (nocturnal) as in the case of Arachnids.
Courtship, Mating, Cannibalism, and Parenting
Codington and Coldwell (2001) opined that life is short for adult males, both because of predation and because they eat little as an adult. Consequently, the female's body size is bigger than male's body.Most males will choose well-fed female than starving female to avoid being eaten as prey, however, pre-and post-copulatory cannibalism occurs in a number of species. Courtship display is signals used to attract the opposite sex such as degree of ornamentation, colors, and movement (Wikipedia, the free Encyclopedia)
- The duration of courtship and copulation varies from seconds to days, but it ends with the insertion of the male pedipalp and transfer of sperm to female gonophore.
- Females store the sperm and later construct a silken egg sac into which 1-250 eggs are placed. Eggs are fertilized only as they exit the female body.
- Parental care is rare and highly variable, ranging from simply guarding the egg sac to actively feeding the young. In one Crab Spider species, the female dies as the juveniles emerged from the egg sac, as they turn to eat their mother's body. In Scorpions, the young is carried in mother's back until they capable of feeding themselves.
- About 20 species of spiders are social, males are rare(1:40-100) generation oftenly overlapped food is shared and prey capture and brood care is cooperative. Colony size varies ranges from a dozen to several thousand individuals (Codington and Colwell,2000).
Significance to Humans
Another oddity among Arachnids is the Order Acari, a taxonomic group less studied of the estimated 500,000 to a million species, only 30,000 are described species. In Greeks, Acari means too little to be divided. Nonetheless, the group Acari comprising the Mites and Ticks deserved utmost attention because of their medical and economic importance to man.Though an important component of ecosystem as decomposer of dead matter, predators of nematodes, fungivores(spore eating), mites, algae, among others, but outweigh these beneficial effects by acting as parasites and vector of viral, fungal, bacterial, and mycoplasma diseases in plants, animals, and humans. Among the Acari, Ticks are major human source of Tick-borne diseases which include, Russian spring-summer encephalitis, Colorado tick fever, African relapsing fever, Lyme disease, Rocky mountain spotted fever, Siberian tick typhus, Q-fever, Homolytic and granulated ehrlichiosis, Kysanor forest disease, and Tularemia(Codington and Colwell,2000)
Arachnids are indeed oddities in the Animal Kingdom. Mistakenly called insects though distantly related, many characteristics are distinctively unique only to Arachnids as Predators, cannibals, and widows, beneficial to the ecosystem but are also harmful as parasites to plant, animals, and humans and also as a vector to a host of human diseases brought by Ticks. Feared and horrifying, the Arachnids have inspired humans since antiquity of their perseverance and persistence. Revered in ancient cultures, worshipped as gods, myths and legends have been ascribed to Arachnids, the unsolved mystery surrounding Arachnid figures in ancient geoglyphs and stone tablets only attest to the oddity of this creatures.
The author would like to acknowledge and thanks the owner(s) of the images/photos used in this article and to HubPages for the opportunity. Likewise, by priority some topics were not included due to lack of time.
Wikipedia, the free encyclopedia
- Cultural depictions of Spiders.
- Evolution of Spiders.
- List of legendary creatures
Myths and Legends
- Arachne, the Greek goddess who became the first spider. Goddessmyths.com
- Black widow spider.OSHA FactSheet. www.osha.gov.
- Hays, j. 2012. Ancient Greeks, Mythical figures and myths. Facts and Details
PDF and non-PDF Articles
- Buddle C. 2014. Smellylegs: Arachnids with unusually glands on the limbs. Scilogs, com
- Buddle, C.2015.Spiderday. Arthropod Ecology.com
- Codington, J, A, and R. K. Colwell. 2001. Arachnids. Smithsonian Institution. The University of Connecticut. Encyclopedia of Biodiversity. Volume 1 (2001), Academic Press. pp. 199-216. Recovered- September 28, 2015.
- Common cryptosphere Arachnids. Tropical Fact Sheets. Recovered September 26, 2015
- Garcia, A. 2014. Opliones and parenthood- the rare exception of maternal and parental care in Arachnids. Invertebrate Zoology. Recovered-September 28, 2015.
- Geologic time scale.University of California Museum of Paleontology.Recovered-October 5, 2015.
- Prehistoric Spiders. enkvillage.com
- Savory, T.!964. Arachnida. Academic Press. Recovered-September 26, 2015
- Spider bites.Ohio State University Extension. Recovered-September 26, 2015.
- Spiders. Texas A and M. AgriLife Extension. Recovered- September 25, 2015.
- USA Spider identification chart- Venomous or Dangerous. Recovered- September 25, 2015