Phylum ArthropodaPhylum Arthropoda

Subphylum TrilobitaSubphylum Trilobita

Subphylum ChelicerataSubphylum Chelicerata

TaxonomyTaxonomy

• Phylum ArthropodaPhylum Arthropoda– Subphylum Trilobita (Extinct) Subphylum Trilobita (Extinct) – Subphylum ChelicerataSubphylum Chelicerata

• Class Merostomata (Horseshoe Crabs)Class Merostomata (Horseshoe Crabs)• Class Arachnida (Spiders, scorpions, and mites)Class Arachnida (Spiders, scorpions, and mites)• Class Pycnogonida (Sea Spiders)Class Pycnogonida (Sea Spiders)

– Subphylum CrustaceaSubphylum Crustacea– Subphylum UniramiaSubphylum Uniramia

• Class ChilopodaClass Chilopoda• Class DiplopodaClass Diplopoda• Class InsectaClass Insecta

General CharacteristicsGeneral Characteristics

• Arthropods have an exoskeleton made up Arthropods have an exoskeleton made up of chitin- a polysaccharide attached to of chitin- a polysaccharide attached to protein. protein.

• Arthropods (‘joint foot’) have jointed Arthropods (‘joint foot’) have jointed appendages. appendages.

• Body is constructed of serially repeated Body is constructed of serially repeated segments (metamerism)segments (metamerism)

• Tagmatization- fusion and specialization of Tagmatization- fusion and specialization of segments.segments.

General CharacteristicsGeneral Characteristics

• TriploblasticTriploblastic

• EucoelomateEucoelomate

• Bilaterally symmetrical.Bilaterally symmetrical.

• Open circulatory system with blood-like Open circulatory system with blood-like tissue called hemolymph.tissue called hemolymph.

• Arthropods must molt, or shed their Arthropods must molt, or shed their exoskeleton, in order to grow in size.exoskeleton, in order to grow in size.

Subphylum TrilobitaSubphylum Trilobita

• Trilobites are an extinct Trilobites are an extinct group of arthropods that group of arthropods that dominated the oceans dominated the oceans before the Mesozoic era.before the Mesozoic era. – Body composed of three Body composed of three

tagmata- head, thorax, tagmata- head, thorax, and abdomenand abdomen

– Biramous, or two-Biramous, or two-branched, appendages.branched, appendages.

– All marine.All marine.

Subphylum ChelicerataSubphylum Chelicerata

• Groups include the horseshoe crabs, sea Groups include the horseshoe crabs, sea spiders, spiders, scorpions, mites, ticks, and spiders, spiders, scorpions, mites, ticks, and others. others.

• Unlike other arthropods, chelicerates do not Unlike other arthropods, chelicerates do not have mandibles used for chewing food. Their have mandibles used for chewing food. Their first pair of appendages (chelicerae) are first pair of appendages (chelicerae) are modified for tearing food apart)modified for tearing food apart)

• Two tagmata- cephalothorax, and abdomen.Two tagmata- cephalothorax, and abdomen.• No antennae.No antennae.

Class MerostomataClass Merostomata

• Horseshoe crabsHorseshoe crabs– Living fossils. Horseshoe crabs have changed little Living fossils. Horseshoe crabs have changed little

in 425 million years!in 425 million years!– All marineAll marine

Class MerostomataClass Merostomata

Class PycnogonidaClass Pycnogonida

• Sea SpidersSea Spiders– Predatory marine chelicerates.Predatory marine chelicerates.– Sea spiders have almost no abdomen. The Sea spiders have almost no abdomen. The

intestines of sea spiders have long diverticula intestines of sea spiders have long diverticula that extend into the legs. that extend into the legs.

– Sea spiders have a long proboscis with a Sea spiders have a long proboscis with a terminal mouth. They feed largely on terminal mouth. They feed largely on cnidarians and other soft-bodied cnidarians and other soft-bodied invertebrates.invertebrates.

Class PycnogonidaClass Pycnogonida

Class PycnogonidaClass Pycnogonida

Class ArachnidaClass Arachnida

• Generally terrestrial with a few aquatic Generally terrestrial with a few aquatic types. types.

• Arachnids possess one pair of chelicerae, Arachnids possess one pair of chelicerae, one pair of pedipalps, and four pair of legs.one pair of pedipalps, and four pair of legs.

• Two tagmata- cephalothorax and Two tagmata- cephalothorax and abdomen.abdomen.

• Class Arachnida is composed of spiders, Class Arachnida is composed of spiders, scorpions, solfugids, mites, ticks, and their scorpions, solfugids, mites, ticks, and their kin. kin.

Class ArachnidaClass Arachnida

http://tolweb.org/tree?group=Arachnida&contgroup=Arthropodahttp://tolweb.org/tree?group=Arachnida&contgroup=Arthropoda

Spider External AnatomySpider External Anatomy

Spider LegsSpider Legs

http://www.uky.edu/Agriculture/CritterFiles/casefile/spiders/anatomy/leg.pnghttp://www.uky.edu/Agriculture/CritterFiles/casefile/spiders/anatomy/leg.png

Spider Internal AnatomySpider Internal Anatomy

SpinneretsSpinnerets

http://www.pbrc.hawaii.edu/bemf/microangela/mspigot7o.jpghttp://www.pbrc.hawaii.edu/bemf/microangela/mspigot7o.jpg

http://www.dianamarques.com/images/spinnerets.jpghttp://www.dianamarques.com/images/spinnerets.jpg

SilkSilk

• Spiders have six Spiders have six spinnerets that can spinnerets that can produce up to seven produce up to seven different types of silk.different types of silk.

• Spider silk is made Spider silk is made of protein and is one of protein and is one of the strongest of the strongest natural substances natural substances in the world. in the world.

SilkSilk

• Silk is produced in Silk is produced in liquid form, but dries liquid form, but dries upon contact with air.upon contact with air.

• All spiders produce All spiders produce silk, but not all spiders silk, but not all spiders spin webs. spin webs.

• Silk is also used for Silk is also used for shelter, reproduction, shelter, reproduction, and drag lines for and drag lines for jumping and jumping and “ballooning.” “ballooning.”

Black Widow Spider (Female)Black Widow Spider (Female)

Brown Recluse SpiderBrown Recluse Spider

TickTick MiteMite

ScorpionScorpion

SolfugidSolfugid(A.K.A. Sun Spider, A.K.A. Camel Spider,(A.K.A. Sun Spider, A.K.A. Camel Spider,

A.K.A. Wind Scorpion)A.K.A. Wind Scorpion)

PseudoscorpionPseudoscorpion