onychophora tardigrada arthropoda nematoda nematomorpha kinorhyncha priapulida loricifera ecdysozoa

Onychophora

Tardigrada

Arthropoda

Nematoda

Nematomorpha

Kinorhyncha

Priapulida

Loricifera

Ecdysozoa

Phylum OnychophoraPhylum Onychophora Phylum Onychophora: Velvet worms, Peripatus.Phylum Onychophora: Velvet worms, Peripatus.

All modern Onychophorans are terrestrial but fossils, All modern Onychophorans are terrestrial but fossils, which date back to the Cambrian, are mainly from which date back to the Cambrian, are mainly from marine sediments.marine sediments.

Onychophorans look a bit like slugs with legs and when Onychophorans look a bit like slugs with legs and when first described in 1825 were thought to be mollusks.first described in 1825 were thought to be mollusks.

However, now placed at the base of the Arthropod family However, now placed at the base of the Arthropod family tree. tree.

http://www.jennifermarohasy.com/blog/archives/Peripatus.jpg

Phylum OnychophoraPhylum Onychophora About 10 genera and approximately 110 species. 1.4-About 10 genera and approximately 110 species. 1.4-

15cm in length.15cm in length.

Geographically widely distributed in suitable moist, humid Geographically widely distributed in suitable moist, humid habitats such as tropical (e.g. Congo, northern South habitats such as tropical (e.g. Congo, northern South America, Himalayas) and southern temperate forest (e.g. America, Himalayas) and southern temperate forest (e.g. New Zealand, Australia, South Africa, Andes).New Zealand, Australia, South Africa, Andes).

Limited habitat distribution (and exclusively nocturnal Limited habitat distribution (and exclusively nocturnal behavior) related to problem of water loss.behavior) related to problem of water loss.

Like other arthropods, Onychophorans have a chitinous Like other arthropods, Onychophorans have a chitinous cuticle, which is molted as they grow, but it is thin and cuticle, which is molted as they grow, but it is thin and flexible, non-waxy and permeable. flexible, non-waxy and permeable.

Phylum OnychophoraPhylum Onychophora

Onychophorans do not have jointed legs, Onychophorans do not have jointed legs, but possess other arthropod but possess other arthropod characteristics including a reduced coleom characteristics including a reduced coleom and a hemocoel.and a hemocoel.

The 14-43 pairs of legs are large and The 14-43 pairs of legs are large and conical with terminal pads and claws. conical with terminal pads and claws. They move using their legs and by They move using their legs and by extending and contracting the body.extending and contracting the body.


Most are predators and use glue which Most are predators and use glue which they can spray from a pair of oral papillae they can spray from a pair of oral papillae to catch their prey.to catch their prey.

They can spray two streams of glue up to They can spray two streams of glue up to 50cm and this hardens almost immediately 50cm and this hardens almost immediately trapping the prey in a net of sticky threads.trapping the prey in a net of sticky threads.


Peripatus video 3 minutesPeripatus video 3 minutes

http://www.youtube.com/watch?http://www.youtube.com/watch?v=FbVDYSiH-Vwv=FbVDYSiH-Vw

Phylum ArthropodaPhylum Arthropoda

The Arthropoda (from the Greek Arthron, The Arthropoda (from the Greek Arthron, joint and podus, foot) are the largest group joint and podus, foot) are the largest group of organisms and they occur in all of organisms and they occur in all environments on earth.environments on earth.

The group includes: spiders, ticks, mites, The group includes: spiders, ticks, mites, centipedes, millipedes, crustaceans, centipedes, millipedes, crustaceans, insects and others.insects and others.

Characteristics of the ArthropodaCharacteristics of the Arthropoda

Bilaterally symmetrical with a segmented Bilaterally symmetrical with a segmented (metameric) body divided into head, thorax (metameric) body divided into head, thorax and abdomen; cephalothorax and and abdomen; cephalothorax and abdomen; or fused head and trunk.abdomen; or fused head and trunk.

http://members.fortunecity.com/nrbq1/gal4arthropod9.jpg

Rove beetle

Goliath bird-eating spiderhttp://animal-world.com/encyclo/reptiles/spiders/images/GoliathBirdEatingSpiderWHSp_AP7I.jpg

http://static.howstuffworks.com/gif/tick-1.jpg

http://repairstemcell.files.wordpress.com/2009/09/tick-bird.jpg

http://www.butterflyrevolt.com/wp-content/uploads/2009/04/centipede.jpg


Jointed appendages. Primitively one pair Jointed appendages. Primitively one pair per segment, but number often reduced. per segment, but number often reduced.

Appendages often greatly modified for Appendages often greatly modified for specialized tasks.specialized tasks.


Exoskeleton of cuticle. Exoskeleton of cuticle.

Exoskeleton secreted by underlying Exoskeleton secreted by underlying epidermis. Made of chitin, protein, lipid epidermis. Made of chitin, protein, lipid and often calcium carbonate.and often calcium carbonate.

Exoskeleton is shed periodically (ecdysis) Exoskeleton is shed periodically (ecdysis) as the organism grows.as the organism grows.


Muscular system is complex and muscles Muscular system is complex and muscles attach to the exoskeleton. attach to the exoskeleton.

Striated muscles for voluntary movement Striated muscles for voluntary movement and smooth muscles for the viscera.and smooth muscles for the viscera.

Coelom is reduced. Most of body cavity is Coelom is reduced. Most of body cavity is a hemocoel (sinuses or spaces) filled with a hemocoel (sinuses or spaces) filled with blood.blood.


Complete digestive system. Mouthparts Complete digestive system. Mouthparts are specialized being modified from are specialized being modified from appendages and specialized for dealing appendages and specialized for dealing with various types of food.with various types of food.

Open circulatory system with a dorsal Open circulatory system with a dorsal contractile heart arteries and hemocoel.contractile heart arteries and hemocoel.


Respiration occurs in multiple possible Respiration occurs in multiple possible waysways across the body surfaceacross the body surface via a system of tracheal tubes (e.g. beetle)via a system of tracheal tubes (e.g. beetle) Gills (e.g. crabs)Gills (e.g. crabs) book lungs (spiders)book lungs (spiders)

Horseshoe crab book gillshttp://library.thinkquest.org/26153/marine/sketch/719a.jpg

http://www.dwm.ks.edu.tw/bio/activelearner/44/images/ch44c3.jpg


Nervous system is similar to that of Nervous system is similar to that of annelids. A dorsal brain connected via a annelids. A dorsal brain connected via a ring around the pharynx to a double ring around the pharynx to a double ventral nerve cord.ventral nerve cord.

http://images.google.com/imgres?imgurl=http://cas.bellarmine.edu/tietjen/Laboratories/Bio%2520Pix%25204%2520U/Image117.gif&imgrefurl=http://cas.bellarmine.edu/tietjen/Ethology/simplenervoussystpix.htm&usg=__hKuhulliD2AlFWkHh8AA6kRX5eo=&h=645&w=1016&sz=42&hl=en&start=4&um=1&tbnid=ORNjwuv-PSCNDM:&tbnh=95&tbnw=150&prev=/images%3Fq%3Darthropod%2Bnervous%2Bsystem%2Bimages%26ndsp%3D18%26hl%3Den%26sa%3DG%26um%3D1


Sexes are usually separate with internal Sexes are usually separate with internal fertilization. fertilization.

Can be oviparous or ovoviviparous. Can be oviparous or ovoviviparous. Offspring often go through process of Offspring often go through process of

metamorphosis.metamorphosis. Parthenogenesis (reproduction without Parthenogenesis (reproduction without

fertilization) occurs in a some species (e.g. fertilization) occurs in a some species (e.g. aphids).aphids).

Aphid giving birthhttp://nathistoc.bio.uci.edu/hemipt/28.jpg

http://anordinarymom.files.wordpress.com/2009/02/metamorphosis-of-monarch-butterfly.jpg

Classification of Phylum ArthropodaClassification of Phylum Arthropoda

Subphylum Chelicerata: horseshoe crabs, Subphylum Chelicerata: horseshoe crabs, spiders, tick, mites, scorpions.spiders, tick, mites, scorpions.

Subphylum Crustacea: crabs, lobsters, Subphylum Crustacea: crabs, lobsters, copepods, barnacles, pill bugs.copepods, barnacles, pill bugs.

Subphylum Myriapoda: millipedes and Subphylum Myriapoda: millipedes and centipedes.centipedes.

Subphylum Hexapoda: springtails, insects.Subphylum Hexapoda: springtails, insects.

Classification of the ArthropodaClassification of the Arthropoda

Subphylum ChelicerataSubphylum Chelicerata Class MerostomataClass Merostomata

• Subclass Xiphosurida: Horseshoe crabsSubclass Xiphosurida: Horseshoe crabs Class Pycnogonida: sea spidersClass Pycnogonida: sea spiders Class Arachnida: spiders, scorpions, ticks, Class Arachnida: spiders, scorpions, ticks,

mites, harvestmen, whip scorpions.mites, harvestmen, whip scorpions.

Subphylum ChelicerataSubphylum Chelicerata

Body is divided into two tagmata (fused Body is divided into two tagmata (fused segments) head and abdomen.segments) head and abdomen.

Six pairs of appendages:Six pairs of appendages: a pair of chelicerae, first pair of appendages used for a pair of chelicerae, first pair of appendages used for

feeding.feeding. a pair of pedipalps (not in horseshoe crabs)a pair of pedipalps (not in horseshoe crabs) 4 pairs of walking legs (5 in horseshoe crabs).4 pairs of walking legs (5 in horseshoe crabs).

No mandibles or antennae.No mandibles or antennae.


The chelicerates are a very ancient group The chelicerates are a very ancient group that includes the extinct Eurypterids (giant that includes the extinct Eurypterids (giant water scorpions (200-500 mya), which water scorpions (200-500 mya), which were the largest known arthropods were the largest known arthropods reaching up to 3m long.reaching up to 3m long.

Eurypterus (left) from the Silurian of New York State. Eurypterus remipes was voted the New York state fossil in 1983.

Mixopterus (right) from the Devonian reached about one meter in length


Subclass Xiphosurida: Horseshoe crabs. Subclass Xiphosurida: Horseshoe crabs. These are an ancient group that date from These are an ancient group that date from the Cambrian (543-495 mya).the Cambrian (543-495 mya).

Five living species. Five living species. LimulusLimulus, which lives in , which lives in shallow waters on the Atlantic coast of the shallow waters on the Atlantic coast of the U.S. is almost unchanged since the U.S. is almost unchanged since the Triassic (251-206 mya).Triassic (251-206 mya).

12.2

Figure 18.02

Subphylum Chelicerata: Horseshoe Subphylum Chelicerata: Horseshoe crabscrabs

Horseshoe crabs have an unsegmented Horseshoe crabs have an unsegmented carapace, which is sort of horseshoe carapace, which is sort of horseshoe shaped, hence the name.shaped, hence the name.

There is also a wide abdomen with a long There is also a wide abdomen with a long spinelike tailpiece (telson).spinelike tailpiece (telson).

Flat leaf-like gills, called book gills, are Flat leaf-like gills, called book gills, are present on the underside.present on the underside.

Horseshoe crabsHorseshoe crabs Horseshoe crabs feed on foods such as worms and Horseshoe crabs feed on foods such as worms and

molluscs, such as clams, which brings them into conflict molluscs, such as clams, which brings them into conflict with fishermen.with fishermen.

The synchronized breeding of horseshoe crabs which The synchronized breeding of horseshoe crabs which come to spawn on the beaches of the mid-Atlantic coast come to spawn on the beaches of the mid-Atlantic coast of the U.S. at the lunar high tides is a striking sight in of the U.S. at the lunar high tides is a striking sight in summer. summer.

The eggs produced in the millions are an important food The eggs produced in the millions are an important food source for migrating shorebirds such as Knot, which source for migrating shorebirds such as Knot, which flock to areas such as the Delaware Bay to fatten up for flock to areas such as the Delaware Bay to fatten up for migration.migration.

Horseshoe crabsHorseshoe crabs

Horseshoe crabs are harvested Horseshoe crabs are harvested commercially for bait and also for their commercially for bait and also for their blood, which is used in laboratory testing blood, which is used in laboratory testing for endotoxins in medical products.for endotoxins in medical products.

Currently, the horseshoe crab is at the Currently, the horseshoe crab is at the center of a series of legal battles about the center of a series of legal battles about the size of harvests and their sustainability.size of harvests and their sustainability.

Subphylum Chelicerata: Class Subphylum Chelicerata: Class Pycnogonida: sea spidersPycnogonida: sea spiders

Another name used for these animals is Another name used for these animals is Pantopoda (“all legs”), which is an excellent Pantopoda (“all legs”), which is an excellent description. description.

The body is greatly reduced in size, whereas the The body is greatly reduced in size, whereas the legs are long and clawed. In some species legs are long and clawed. In some species modified legs called ovigers are used by males modified legs called ovigers are used by males to carry egg masses.to carry egg masses.

There is a long proboscis on the head, which the There is a long proboscis on the head, which the pycnogonid uses to feed on soft-bodied pycnogonid uses to feed on soft-bodied invertebrates, especially cnidarians.invertebrates, especially cnidarians.

http://www.mbari.org/news/feature-image/pycnogonid-450.jpg

12.3

Figure 18.03

Class Pycnogonida: sea spidersClass Pycnogonida: sea spiders

Most pycnogonids are small being only a Most pycnogonids are small being only a few millimeters long, but a few reach 70cm few millimeters long, but a few reach 70cm measured by leg spread.measured by leg spread.

Pycngonids are exclusively marine Pycngonids are exclusively marine (occuring from the intertidal to the deep (occuring from the intertidal to the deep seas) and there are about 1000 species.seas) and there are about 1000 species.

Subphylum Chelicerata: Class Subphylum Chelicerata: Class Arachnida: Order Aranae: spidersArachnida: Order Aranae: spiders

Spiders are a very large group with more than 35,000 Spiders are a very large group with more than 35,000 described species that occur worldwide except in described species that occur worldwide except in Antarctica.Antarctica.

The body is divided into a cephalothorax and an The body is divided into a cephalothorax and an abdomen.abdomen.

Spiders breathe using book lungs or tracheae. Book Spiders breathe using book lungs or tracheae. Book lungs are unique to spiders and consist of a large lungs are unique to spiders and consist of a large number of air pockets extending into a blood-filled number of air pockets extending into a blood-filled chamber. Tracheae are tubules that carry air directly chamber. Tracheae are tubules that carry air directly from outside to tissues. They can be closed to prevent from outside to tissues. They can be closed to prevent excessive water loss.excessive water loss.

SpidersSpiders

Spiders and insects have an excretory system Spiders and insects have an excretory system that uses structures called Malphigian tubules.that uses structures called Malphigian tubules.

Potassium, other salts, and other waste solutes Potassium, other salts, and other waste solutes drain into these tubules, which empty into the drain into these tubules, which empty into the intestine. Rectal glands selectively reabsorb intestine. Rectal glands selectively reabsorb most of the potassium and water leaving behind most of the potassium and water leaving behind nitrogenous wastes in the form of uric acid, nitrogenous wastes in the form of uric acid, which requires little water for its excretion.which requires little water for its excretion.

http://www.earthlife.net/chelicerata/images/spider-guts.gif

SpidersSpiders

Most spiders possess eight eyes (some Most spiders possess eight eyes (some have a few as two), but their image have a few as two), but their image forming ability is limited. forming ability is limited.

Hairlike setae, however, provide a lot of Hairlike setae, however, provide a lot of information about the environment sensing information about the environment sensing e.g. vibrations and air currentse.g. vibrations and air currents

http://www.eurospiders.com/spider_eyes.jpg

SpidersSpiders

All spiders are predators and their chelicerae All spiders are predators and their chelicerae function as fangs. function as fangs.

The fangs are connected via ducts to venom The fangs are connected via ducts to venom glands that produce a lethal venom the spider glands that produce a lethal venom the spider uses to dispatch its prey.uses to dispatch its prey.

After killing a prey item the spider injects After killing a prey item the spider injects digestive fluid into the organism and sucks up digestive fluid into the organism and sucks up the resulting soup.the resulting soup.

12.4

Figure 18.05

SpidersSpiders

Spiders use a variety of techniques to Spiders use a variety of techniques to catch prey. catch prey.

Some chase their prey or leap on it, some Some chase their prey or leap on it, some ambush prey often using trip wires, and, of ambush prey often using trip wires, and, of course, many use webs. course, many use webs.

Trapdoor spiderTrapdoor spider

http://www.youtube.com/watch?http://www.youtube.com/watch?v=7yJgPVxS5aI&list=PLr96eNfxmgJRv9Alv=7yJgPVxS5aI&list=PLr96eNfxmgJRv9AlzVs35QmybWaKUlPsbzVs35QmybWaKUlPsb

One small group, the bolas spiders, One small group, the bolas spiders, capture their prey by deception.capture their prey by deception.

http://www.youtube.com/watch?http://www.youtube.com/watch?v=2UfMJJAzvbI&list=PLr96eNfxmgJRv9Alv=2UfMJJAzvbI&list=PLr96eNfxmgJRv9AlzVs35QmybWaKUlPsbzVs35QmybWaKUlPsb

Bolas spider 2’55”Bolas spider 2’55”

Bolas spidersBolas spiders Bolas spiders at night spin a line of thread with a sticky Bolas spiders at night spin a line of thread with a sticky

globule the bolas (akin to the bolas used by South globule the bolas (akin to the bolas used by South American Gauchos to hunt) at the free end. American Gauchos to hunt) at the free end.

The bolas contains pheromones which attract certain The bolas contains pheromones which attract certain male moths which think they are approaching a female. male moths which think they are approaching a female. When the spider senses the vibrations in the air caused When the spider senses the vibrations in the air caused by a nearby flying moth it twirls its bolas in response. by a nearby flying moth it twirls its bolas in response.

Once the bolas strikes the moth it sticks and the moth is Once the bolas strikes the moth it sticks and the moth is hauled in.hauled in.

Gladiator spiderGladiator spider

The gladiator spider throws a net of silk to The gladiator spider throws a net of silk to catch its prey catch its prey

http://www.youtube.com/watch?http://www.youtube.com/watch?v=rLSg_OKMi0I&list=PLr96eNfxmgJRv9Alv=rLSg_OKMi0I&list=PLr96eNfxmgJRv9AlzVs35QmybWaKUlPsbzVs35QmybWaKUlPsb

2 min2 min

Silk-spinningSilk-spinning Spiders spin silk, which they use to make webs Spiders spin silk, which they use to make webs

to trap prey. to trap prey.

Webs come in a variety of shapes and sizes and Webs come in a variety of shapes and sizes and contain and are coated with an adhesive that contain and are coated with an adhesive that holds prey. holds prey.

Webs are typically placed in insect flyways and Webs are typically placed in insect flyways and the spider sits and waits for an insect to become the spider sits and waits for an insect to become entangled. The vibrations of the struggling prey entangled. The vibrations of the struggling prey signal the spider to emerge and dispatch it.signal the spider to emerge and dispatch it.

Silk-spinningSilk-spinning

The silk is produced by two or three spinnerets, The silk is produced by two or three spinnerets, which are connected to abdominal silk glands. which are connected to abdominal silk glands. The silk is formed from a protein secretion that The silk is formed from a protein secretion that hardens on contact with air. hardens on contact with air.

The silk is extremely strong (stronger e.g. than The silk is extremely strong (stronger e.g. than steel of equivalent weight) and is being used as steel of equivalent weight) and is being used as a kevlar substitute. Unlike steel, silk can stretch a kevlar substitute. Unlike steel, silk can stretch which makes it an extremely useful material.which makes it an extremely useful material.

Web buildingWeb building

http://www.youtube.com/watch?http://www.youtube.com/watch?v=eb6bqIWdQaov=eb6bqIWdQao

3 minutes3 minutes

Silk-spinningSilk-spinning

The silk is used to make webs, but also for The silk is used to make webs, but also for a variety of other purposes:a variety of other purposes: Line nestsLine nests Form egg sacsForm egg sacs For dispersal by ballooningFor dispersal by ballooning To wrap preyTo wrap prey

Reproduction in spidersReproduction in spiders

Courtship rituals are a major feature of Courtship rituals are a major feature of spider mating in which the (usually much spider mating in which the (usually much smaller) male attempts to mate without smaller) male attempts to mate without being eaten by the female. being eaten by the female.

Males produce a sperm packet wrapped in Males produce a sperm packet wrapped in silk which he holds in a cavity in one of his silk which he holds in a cavity in one of his pedipalps (second pair of appendages).pedipalps (second pair of appendages).

Reproduction in spidersReproduction in spiders

The male, if he lives long enough, inserts a The male, if he lives long enough, inserts a pedipalp into a female’s genital opening and she pedipalp into a female’s genital opening and she stores the sperm in a seminal vesicle. stores the sperm in a seminal vesicle.

The female later fertilizes eggs when she is The female later fertilizes eggs when she is ready to lay them. Eggs are laid in a silk cocoon ready to lay them. Eggs are laid in a silk cocoon where the young hatch and remain for a short where the young hatch and remain for a short time and molt before departing for an time and molt before departing for an independent life.independent life.

Argiope spider matingArgiope spider mating

http://www.youtube.com/watch?http://www.youtube.com/watch?v=xPvCIrYrs5k&list=PLr96eNfxmgJRv9Alzv=xPvCIrYrs5k&list=PLr96eNfxmgJRv9AlzVs35QmybWaKUlPsbVs35QmybWaKUlPsb

Toxic spidersToxic spiders

The vast majority of spiders are harmless The vast majority of spiders are harmless to humans, but a handful are toxic and to humans, but a handful are toxic and potentially deadly.potentially deadly.

In the U.S. there are a few venomous In the U.S. there are a few venomous spiders: several black widow species spiders: several black widow species (genus (genus LatrodectusLatrodectus), the brown recluse ), the brown recluse ((Loxosceles reclusaLoxosceles reclusa) and the hobo spider ) and the hobo spider ((Tegenaria agrestisTegenaria agrestis) introduced from ) introduced from Europe to the Pacific Northwest.Europe to the Pacific Northwest.


Spiders eat a liquid diet by injecting Spiders eat a liquid diet by injecting digestive juices into their prey and some digestive juices into their prey and some spider venoms contribute to this process spider venoms contribute to this process by destroying tissue. by destroying tissue.

Bites of such spiders can lead to tissue Bites of such spiders can lead to tissue necrosis. This is the type of venom necrosis. This is the type of venom possessed by the hobo and brown recluse possessed by the hobo and brown recluse spiders.spiders.

Hobo spider

Brown recluse spider


A bite from one of these spiders results in A bite from one of these spiders results in a bite site that develops a painful ulcer a bite site that develops a painful ulcer where tissue dies (necrosis) and in the where tissue dies (necrosis) and in the case of hobo spiders severe headaches.case of hobo spiders severe headaches.

One component of brown recluse venom One component of brown recluse venom is sphingomyelinase D which attacks and is sphingomyelinase D which attacks and dissolves cell membranes. dissolves cell membranes.

“Many medical conditions are mistaken for brown recluse bites. The wound on the left is from a brown recluse spider, the oneon the right from a bacterial infection.” http://www.ca.uky.edu/entomology/entfacts/ef631.asp


Sphingomyelinase D and other components in Sphingomyelinase D and other components in the venom apparently also turn on the patient’s the venom apparently also turn on the patient’s inflammatory defenses against his or her own inflammatory defenses against his or her own tissues.tissues.

White blood cells destroy themselves releasing White blood cells destroy themselves releasing other enzymes that attack the victim’s own flesh other enzymes that attack the victim’s own flesh and blood clots form in tiny vessels cutting off and blood clots form in tiny vessels cutting off the blood supply to the bite area and causing the blood supply to the bite area and causing necrosis.necrosis.


Generally, bites are not fatal but if the Generally, bites are not fatal but if the venom gets into the bloodstream it may venom gets into the bloodstream it may destroy red blood cells or attack the bone destroy red blood cells or attack the bone marrow, which may lead to fatal marrow, which may lead to fatal complications.complications.


Black widow spiders and the funnel web Black widow spiders and the funnel web spider (one of the world’s most dangerous spider (one of the world’s most dangerous species [naturally it’s from Australia!]) species [naturally it’s from Australia!]) produce potent neurotoxins that affect the produce potent neurotoxins that affect the nervous system.nervous system.

Female Black Widow spider with egg sac


Venom is complex and many components Venom is complex and many components only affect invertebrates, but one only affect invertebrates, but one substance in black widow venom called substance in black widow venom called alpha latrotoxin stimulates cells to release alpha latrotoxin stimulates cells to release neurotransmitters such as acetylcholine. neurotransmitters such as acetylcholine.

Nerves contract uncontrollably and this Nerves contract uncontrollably and this can cause small muscle rigidity and can cause small muscle rigidity and intense, agonizing pain.intense, agonizing pain.


Additional symptoms include nausea and Additional symptoms include nausea and vomiting, increased blood pressure, and vomiting, increased blood pressure, and the heart may begin racing or slowing the heart may begin racing or slowing significantly.significantly.

Brain functions may also be affected Brain functions may also be affected producing anxiety, amnesia, and even producing anxiety, amnesia, and even psychosis.psychosis.


Black widow bites were historically often Black widow bites were historically often associated with outhouses, but now usually associated with outhouses, but now usually occur when working in the fields or clearing junk occur when working in the fields or clearing junk in outbuildings.in outbuildings.

Fatality rates have been estimated at 1-5%, but Fatality rates have been estimated at 1-5%, but this figure certainly is an overestimate as many this figure certainly is an overestimate as many people bitten do not seek medical attention. people bitten do not seek medical attention. Those most at risk are small children and the Those most at risk are small children and the elderly.elderly.


Funnel web spiders (especially the Sydney Funnel web spiders (especially the Sydney funnel web spider) are extremely dangerous. funnel web spider) are extremely dangerous.

Funnel web spiders inject a venom whose lethal Funnel web spiders inject a venom whose lethal component is called atrotoxin. component is called atrotoxin.

The toxin travels in the lymphatic system and The toxin travels in the lymphatic system and binds to nerve endings all over the body where it binds to nerve endings all over the body where it causes nerves to discharge wildly, especially causes nerves to discharge wildly, especially those of the autonomic nervous system.those of the autonomic nervous system.

Funnel web spiders

Funnel web spider burrow site

http://www.youtube.com/watch?http://www.youtube.com/watch?v=EC11GxIMURcv=EC11GxIMURc

Sydney funnel web spider 4’30”Sydney funnel web spider 4’30”


The constant discharging of the autonomic The constant discharging of the autonomic nervous system results in fever, irregular nervous system results in fever, irregular heart rhythm and wild changes in heart heart rhythm and wild changes in heart rate and blood pressure that can cause rate and blood pressure that can cause respiratory failure, coma and cardiac respiratory failure, coma and cardiac arrest.arrest.

Death may occur anything from 15 Death may occur anything from 15 minutes to 6 days after a bite. minutes to 6 days after a bite.


Work by Dr. Struan Sutherland and Work by Dr. Struan Sutherland and colleagues in Melbourne has led to colleagues in Melbourne has led to success in treating funnel web spider bites success in treating funnel web spider bites and greatly reduced mortality. and greatly reduced mortality.

Dr Sutherland pioneered the use of Dr Sutherland pioneered the use of pressure bandages to prevent the pressure bandages to prevent the spreading of the venom and led the team spreading of the venom and led the team that developed successful antivenins.that developed successful antivenins.

Subphylum Chelicerata: Order Subphylum Chelicerata: Order Scorpionida: ScorpionsScorpionida: Scorpions

There are about 1,500 species of There are about 1,500 species of scorpions and the group includes some of scorpions and the group includes some of the largest of the arachnids as some the largest of the arachnids as some scorpions reach up to 18cm in length.scorpions reach up to 18cm in length.

Scorpions are best known for their Scorpions are best known for their prominent front claws, which are modified prominent front claws, which are modified pedipalps and their stinging tail, with which pedipalps and their stinging tail, with which they inject venom.they inject venom.

ScorpionsScorpions

Scorpions have a body that consists of a Scorpions have a body that consists of a quite short cephalothorax, which bears 4 quite short cephalothorax, which bears 4 pairs of walking legs and a long, pairs of walking legs and a long, segmented abdomen which is divided into segmented abdomen which is divided into a thick preabdomen and a thinner a thick preabdomen and a thinner postabdomen that carries the stinging postabdomen that carries the stinging apparatus.apparatus.

http://www.photographytips.com/page.cfm/31994

Giant desert hairy scorpion

by Rhonda Spencer

ScorpionsScorpions

Scorpions glow when a black light (UV Scorpions glow when a black light (UV light) is shone on them. This is because light) is shone on them. This is because the cuticle contains a variety of fluorescent the cuticle contains a variety of fluorescent compounds. compounds.

This characteristic makes nocturnal This characteristic makes nocturnal surveys of scorpions quite easy.surveys of scorpions quite easy.

http://fireflyforest.net/firefly/2006/11/13/fluorescent-scorpion-in-uv-light/

ScorpionsScorpions

Scorpions occur on all continents except Scorpions occur on all continents except Antarctica.Antarctica.

They are commonest in tropical and They are commonest in tropical and subtropical areas, but some occur in subtropical areas, but some occur in colder areas including high mountain tops. colder areas including high mountain tops.

ScorpionsScorpions

Scorpions are generally secretive and hide from Scorpions are generally secretive and hide from potential predators during the day in crevices potential predators during the day in crevices before emerging to feed at night on insects and before emerging to feed at night on insects and similar prey. The largest species may kill small similar prey. The largest species may kill small reptiles and mammals.reptiles and mammals.

Scorpion’s liking for dark places to hide is why Scorpion’s liking for dark places to hide is why it’s important to shake out your shoes in the it’s important to shake out your shoes in the morning in scorpion country.morning in scorpion country.

FeedingFeeding

Scorpion pincers are covered in highly sensitive Scorpion pincers are covered in highly sensitive hairs and respond quickly to prey that brush hairs and respond quickly to prey that brush against them.against them.

Prey is gripped with the pincers (pedipalps) and Prey is gripped with the pincers (pedipalps) and either crushed or stung to death. Scorpions either crushed or stung to death. Scorpions consume only liquids so the prey is torn into tiny consume only liquids so the prey is torn into tiny pieces using the jawlike chelicerae and pieces using the jawlike chelicerae and predigested in a pre-oral cavity below the predigested in a pre-oral cavity below the chelicerae until it liquifies and is then consumed.chelicerae until it liquifies and is then consumed.

Scorpion toxicityScorpion toxicity

The venom of most species of scorpions is not The venom of most species of scorpions is not harmful to humans, but that of some African harmful to humans, but that of some African species and some found in Mexico and the species and some found in Mexico and the southwestern U.S. can be fatal. southwestern U.S. can be fatal.

In all about 25 species are potentially dangerous In all about 25 species are potentially dangerous to humans. The venom is a mix of compounds to humans. The venom is a mix of compounds that includes neurotoxins and enzyme inhibitors. that includes neurotoxins and enzyme inhibitors. One short chain scorpion toxin is known to block One short chain scorpion toxin is known to block KK++ channels in cell membranes. channels in cell membranes.

ScorpionsScorpions

Because scorpions have a low metabolic Because scorpions have a low metabolic rate and are relatively inactive they can go rate and are relatively inactive they can go for long periods between meals.for long periods between meals.

Some species can survive 6-12 months of Some species can survive 6-12 months of starvation.starvation.

Scorpion courtshipScorpion courtship

Most scorpions reproduce sexually Most scorpions reproduce sexually although a few species are known to although a few species are known to reproduce parthenogenetically.reproduce parthenogenetically.

There is a complex courtship ritual in There is a complex courtship ritual in which the male grips the females claws which the male grips the females claws and dances with her as he attempts to and dances with her as he attempts to maneuver her over a spermatophore he maneuver her over a spermatophore he has produced.has produced.

ScorpionsScorpions

Scorpions are viviparous (give birth to live Scorpions are viviparous (give birth to live young) and these stay with their mother young) and these stay with their mother and ride on her back until they undergo and ride on her back until they undergo their first molt. They depend on their their first molt. They depend on their mother for protection and to regulate mother for protection and to regulate humidity levels.humidity levels.

The young go through 5-7 molts (instars) The young go through 5-7 molts (instars) before reaching maturity.before reaching maturity.

12.10 a

Figure 18.10a

Order Uropygidi: whip scorpions Order Uropygidi: whip scorpions and Order Amblypygi: tail-less whip and Order Amblypygi: tail-less whip

scorpionsscorpions

The members of these two groups are The members of these two groups are similar in appearance to scorpions, but similar in appearance to scorpions, but lack the stinging apparatus in the tail.lack the stinging apparatus in the tail.

The abdomen of these organisms either The abdomen of these organisms either ends in a long tail [which has a sensory ends in a long tail [which has a sensory function] or there is no tail (hence the function] or there is no tail (hence the common names of the two groups).common names of the two groups).

Amblypygid(bottom left and below)

Uropygid (left)

Order Uropygidi: whip scorpions Order Uropygidi: whip scorpions and Order Amblypygi: tail-less whip and Order Amblypygi: tail-less whip

scorpionsscorpions

Uropygids are often called vinegaroons because Uropygids are often called vinegaroons because they can spray an acidic solution from their tails. they can spray an acidic solution from their tails.

Both groups are predatory and there are about Both groups are predatory and there are about 100 described species of Uropygids and about 100 described species of Uropygids and about 130 species of Amblypygids. Both groups are 130 species of Amblypygids. Both groups are found in tropical and subtropical areas and a few found in tropical and subtropical areas and a few species occur in the southern U.S.species occur in the southern U.S.

Uropygids and AmblypygidsUropygids and Amblypygids

Both groups use 6 legs for walking the first Both groups use 6 legs for walking the first pair having been modified into antennae-pair having been modified into antennae-like sensory organs.like sensory organs.

Both groups are carnivorous nocturnal Both groups are carnivorous nocturnal hunters that feed mostly on insects and hunters that feed mostly on insects and other arthropods.other arthropods.

Uropygids and AmblypygidsUropygids and Amblypygids

Many behaviors of Uropygids and Many behaviors of Uropygids and Amblypygids are similar to those of Amblypygids are similar to those of scorpions.scorpions.

They avoid light as do scorpions, hide in They avoid light as do scorpions, hide in crevices and the young travel on their crevices and the young travel on their mother’s back when smallmother’s back when small

Subphylum Chelicerata: Order Subphylum Chelicerata: Order Opiliones: harvestmenOpiliones: harvestmen

Harvestmen or “daddy longlegs” are Harvestmen or “daddy longlegs” are common and easily separated from common and easily separated from spiders by a number of features:spiders by a number of features: Their abdomen and cephalothorax are not Their abdomen and cephalothorax are not

separated by a narrow “waist” or pedicel as separated by a narrow “waist” or pedicel as they are in spiders.they are in spiders.

They usually have extremely long thin legs. They usually have extremely long thin legs. They cannot spin silk.They cannot spin silk. They have only two eyes rather than then the They have only two eyes rather than then the

eight of spiders.eight of spiders.

HarvestmenHarvestmen

The chelicerae of harvestmen are The chelicerae of harvestmen are pincerlike and they use them to catch pincerlike and they use them to catch small insects and also commonly small insects and also commonly scavenge dead items.scavenge dead items.

Unlike spiders they can eat solid foodUnlike spiders they can eat solid food

There are about 6400 described species.There are about 6400 described species.

HarvestmenHarvestmen

Most harvestmen reproduce sexually although Most harvestmen reproduce sexually although pathenogenesis occurs in some speciespathenogenesis occurs in some species

In some species the male guards the female In some species the male guards the female after mating and in others the male defends a after mating and in others the male defends a territory where females come to lay eggs. The territory where females come to lay eggs. The male tends the eggs until they hatch and male tends the eggs until they hatch and defends the eggs against predators including defends the eggs against predators including females who come to lay.females who come to lay.

Subphylum Chelicerata: Order Subphylum Chelicerata: Order Acari: ticks and mitesAcari: ticks and mites

The members of the Acari differ from the The members of the Acari differ from the other Arachnids in that their cephalothorax other Arachnids in that their cephalothorax and abdomen are completely fused with and abdomen are completely fused with no evidence of a division between the no evidence of a division between the segments.segments.

The mouthparts are mounted on a small The mouthparts are mounted on a small projection called a capitulum.projection called a capitulum.

Wood tick

Figure 18.11a

Wood tick

Ticks and mitesTicks and mites

An estimated 25,000 species of Acarines occur An estimated 25,000 species of Acarines occur worldwide in a wide variety of habitats on the worldwide in a wide variety of habitats on the ground, in vegetation, in freshwater and marine ground, in vegetation, in freshwater and marine habitats often as ectoparasites.habitats often as ectoparasites.

The group includes a number of major pests The group includes a number of major pests including spider mites, which are serious including spider mites, which are serious agricultural pests, chiggers and ticks which are agricultural pests, chiggers and ticks which are ectoparasites and spread a variety of unpleasant ectoparasites and spread a variety of unpleasant diseases.diseases.

Disease carrying ticksDisease carrying ticks

Ticks are usually bigger than mites and feed on Ticks are usually bigger than mites and feed on the blood of vertebrates.the blood of vertebrates.

They wait on vegetation until they sense the They wait on vegetation until they sense the presence of a suitable host and then grasp on.presence of a suitable host and then grasp on.

They will attach by inserting their chelicerae and They will attach by inserting their chelicerae and a feeding tube called a hypostome and generally a feeding tube called a hypostome and generally feed for several days (increasing enormously in feed for several days (increasing enormously in size) and eventually drop off.size) and eventually drop off.


Once a tick drops off it will digest its meal Once a tick drops off it will digest its meal and molt before feeding again. and molt before feeding again.

Because they feed on blood, ticks, like Because they feed on blood, ticks, like mosquitoes, are major vectors of disease.mosquitoes, are major vectors of disease.


A wide variety of diseases are tick borne, A wide variety of diseases are tick borne, with ticks being second only to mosquitoes with ticks being second only to mosquitoes in the variety and seriousness of the in the variety and seriousness of the conditions they spread.conditions they spread.

Diseases spread include Rocky Mountain Diseases spread include Rocky Mountain spotted fever, tularemia, red-water fever spotted fever, tularemia, red-water fever and best known of course Lyme Disease.and best known of course Lyme Disease.

Lyme DiseaseLyme Disease

Lyme Disease (named for Lyme Connecticut Lyme Disease (named for Lyme Connecticut where it was first described from) is caused by a where it was first described from) is caused by a bacterium bacterium Borrelia burgdorferiBorrelia burgdorferi. .

Symptoms of Lyme disease, which is spread by Symptoms of Lyme disease, which is spread by the bite of a deer tick, include fever, headache, the bite of a deer tick, include fever, headache, fatigue, and a diagnostic skin rash called fatigue, and a diagnostic skin rash called erythema migrans, which has a bull’s eye erythema migrans, which has a bull’s eye appearance.appearance.

Lyme DiseaseLyme Disease If not treated, an infection with If not treated, an infection with BorreliaBorrelia

burgdorferiburgdorferi can spread to the joints producing can spread to the joints producing arthritis-like symptoms as well as to the heart, arthritis-like symptoms as well as to the heart, and nervous system, which may result in facial and nervous system, which may result in facial palsy.palsy.

Lyme disease can be treated with antibiotics if Lyme disease can be treated with antibiotics if caught early enough. caught early enough.

Prompt removal of ticks from clothing and of Prompt removal of ticks from clothing and of attached ticks is important in avoiding infection.attached ticks is important in avoiding infection.

Commensal mitesCommensal mites

A variety of mites live commensally with us A variety of mites live commensally with us including tiny species that live in hair including tiny species that live in hair follicles especially around the nose and follicles especially around the nose and eyes. eyes.

These mites (<0.4mm long) are vaguely These mites (<0.4mm long) are vaguely wormlike having quite long bodies and live wormlike having quite long bodies and live head down in follicles feeding on dead head down in follicles feeding on dead skin cells and secretions. skin cells and secretions.

Eyelash mites. Above left: three embedded head down in a follicle; aboveright an individual Demodex folliculorumand right close up of the anterior end.

Commensal MitesCommensal Mites

In addition to follicle mites, dust mites are In addition to follicle mites, dust mites are extremely common and feed on the dead extremely common and feed on the dead flakes of skin that we shed every day flakes of skin that we shed every day (that’s what most dust is).(that’s what most dust is).

Your pillow is home to thousands of them!Your pillow is home to thousands of them!

Figure 18.12

Dust mite

ChiggersChiggers Chiggers are tiny mites (< 0.05 mm long), but Chiggers are tiny mites (< 0.05 mm long), but

cause skin irritations out of all proportion to their cause skin irritations out of all proportion to their size.size.

Chigger larvae climb on to vegetation and wait to Chigger larvae climb on to vegetation and wait to hitch a ride on a passing animal.hitch a ride on a passing animal.

The larva pierces the skin and injects a salivary The larva pierces the skin and injects a salivary secretion of powerful, digestive enzymes that secretion of powerful, digestive enzymes that break down skin cells into a liquid, which the break down skin cells into a liquid, which the chigger ingests. chigger ingests.

ChiggersChiggers

The digestive enzymes also causes the The digestive enzymes also causes the surrounding tissue to become harder, which surrounding tissue to become harder, which generates a feeding tube (called a stylostome) generates a feeding tube (called a stylostome) of hardened flesh through which more semi-of hardened flesh through which more semi-digested skin cells are consumed. digested skin cells are consumed.

After about four days the larva finishes feeding After about four days the larva finishes feeding and drops off its host, leaving behind a red welt and drops off its host, leaving behind a red welt that itches severely. Although very irritating U.S. that itches severely. Although very irritating U.S. chiggers do not spread disease.chiggers do not spread disease.

onychophora tardigrada arthropoda nematoda nematomorpha kinorhyncha priapulida loricifera ecdysozoa

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