ArthropodsArthropods

Jessica CorleyJessica CorleyAndrew LightfootAndrew LightfootJohnny ChenJohnny Chen

General Arthropod TermsGeneral Arthropod Terms Cuticle: The exoskeleton of an arthropod, consisting of protein and Cuticle: The exoskeleton of an arthropod, consisting of protein and

chitin that are variously modified for functionchitin that are variously modified for function

Exoskeleton: A hard encasement on the surface of an animal that Exoskeleton: A hard encasement on the surface of an animal that provides protectionprovides protection

Molting: The process in which the exoskeleton is shed at intervals to Molting: The process in which the exoskeleton is shed at intervals to allow growth by the creation of a larger exoskeletonallow growth by the creation of a larger exoskeleton

Book Lungs: Organs of gas exchange in spiders, consisting of Book Lungs: Organs of gas exchange in spiders, consisting of stacked plates contained in an internal chamberstacked plates contained in an internal chamber

A cricket undergoing molting

General Terms (Cont..)General Terms (Cont..)

Open Circulatory System: An arrangement of internal transport in which blood Open Circulatory System: An arrangement of internal transport in which blood bathes the organs directly. There is no distinction between blood and intestinal bathes the organs directly. There is no distinction between blood and intestinal fluidfluid

Chelicerae: Pointed appendages Chelicerae: Pointed appendages

which are used to grasp food; which are used to grasp food;

some can contain venom glandssome can contain venom glands

Mandibles: Pair of mouthparts used for eating that can actually chew food unlike Mandibles: Pair of mouthparts used for eating that can actually chew food unlike cheliceraechelicerae

Antennae: Pair of sensory organs joined at the base, functions can vary from Antennae: Pair of sensory organs joined at the base, functions can vary from organism to organism, including smelling, tasting, and sensing vibrations (sort of organism to organism, including smelling, tasting, and sensing vibrations (sort of like hearing).like hearing).

General Terms (Cont……….)General Terms (Cont……….) Compound Eyes: Eyes of an arthropod that consist of several ommatidia, tiny Compound Eyes: Eyes of an arthropod that consist of several ommatidia, tiny

independent photoreception units independent photoreception units

Malpighian tubules: Excretory organs that remove metabolic wastes from the Malpighian tubules: Excretory organs that remove metabolic wastes from the ArthropodsArthropods

Complete Metamorphosis: Arthropods with a larval stage that is made to eat and grow. These arthropods look completely different from their adult forms.

Incomplete Metamorphosis: Arthropods that resemble adults during the larval stages. With each successive molting, the arthropod becomes an adult

Tracheal System: Responsible for gas exchange in arthropods; consists of branched, chitin-lined tubes that carry oxygen directly to the cells

Spiracles: Pores that open to the outside of the body that open and close to regulate air flow and reduce water loss

Antennae

Chelicerae

Compound eye

Mandible

Exoskeleton/ Cuticle

Segmented Legs

1

2

3

4

5

6

Dorsal View of Lobster

ClassesClassesArachnidaArachnida Body has one or two main part, six pairs Body has one or two main part, six pairs

of appendages (chelicerae, pedipalps, of appendages (chelicerae, pedipalps, and 4 pairs of legs) terrestrialand 4 pairs of legs) terrestrial

Spiders, Spiders,

scorpions,scorpions,

ticks, mitesticks, mites

DiplopodaDiplopoda Body with distinct head bearing Body with distinct head bearing antennae and mouthparts, segmented antennae and mouthparts, segmented body with 2 pairs of legs per segment body with 2 pairs of legs per segment terrestrial, herbivorousterrestrial, herbivorous

Millipedes Millipedes

ChilopodaChilopoda Body with distinct head with antennae Body with distinct head with antennae and 3 pairs of mouthparts, first body and 3 pairs of mouthparts, first body segment has poison claws, following segment has poison claws, following segments have 2 legs, terr., carnivoresegments have 2 legs, terr., carnivore

CentipedesCentipedes

InsectaInsecta Body divided into head, thorax, and Body divided into head, thorax, and abdomen, antennae, mouthparts abdomen, antennae, mouthparts modified to chew, suck, or lap, 2 pairs of modified to chew, suck, or lap, 2 pairs of wings, 3 sets of legs, most terr.wings, 3 sets of legs, most terr.

InsectsInsects

CrustaceaCrustacea Body divided into two or three parts, Body divided into two or three parts, antennae, chewing mouthparts, 3 or antennae, chewing mouthparts, 3 or more pairs of legs, most marine more pairs of legs, most marine

Crabs, lobsters,Crabs, lobsters,

Crayfish, Crayfish,

shrimpshrimp

A Few Orders of InsectsA Few Orders of InsectsColeopteraColeoptera Two Pairs of wings, armored Two Pairs of wings, armored

exoskeleton, biting and chewing exoskeleton, biting and chewing mouthparts, complete metamorphosismouthparts, complete metamorphosis

BeetlesBeetles

Diptera Diptera One pair of wings and halteres One pair of wings and halteres (balancing organs); sucking, piercing, (balancing organs); sucking, piercing, or lapping mouthparts, complete meta.or lapping mouthparts, complete meta.

Flies, Flies,

MosquitoesMosquitoes

HymenopteraHymenoptera Two pairs of membranous wings; head Two pairs of membranous wings; head mobile; chewing of sucking mobile; chewing of sucking mouthparts; posterior stinging organ on mouthparts; posterior stinging organ on females; complete metamorphosis; females; complete metamorphosis; many species socialmany species social

Ants,Ants,

Bees,Bees,

WaspsWasps

LepidopteraLepidoptera 2 pairs of wings with tiny scales; long, 2 pairs of wings with tiny scales; long, coiled tongue for sucking; complete coiled tongue for sucking; complete metamorphosismetamorphosis

Butterflies,Butterflies,

mothsmoths

OrthopteraOrthoptera 2 pairs of wings; biting and chewing 2 pairs of wings; biting and chewing mouthparts; incomplete mouthparts; incomplete metamorphosismetamorphosis

Crickets,Crickets,

Roaches,Roaches,

GrasshoppersGrasshoppers

mantidsmantids

General Arthropod InformationGeneral Arthropod Information

Bilateral symmetryBilateral symmetry

3 Germ Layers, and a real 3 Germ Layers, and a real coelemcoelem

The more dominant body cavity The more dominant body cavity is called hemocoel. This is filled is called hemocoel. This is filled with hemolymph, a mixture of with hemolymph, a mixture of blood, lymph, and tissue fluidblood, lymph, and tissue fluid

Open circulatory system (the Open circulatory system (the cause of a hemocoel)cause of a hemocoel)

ProtostomesProtostomesLobster demonstrating bilateral

symmetry

MovementMovement

Arthropods are sessileArthropods are sessile

Arthropods are Arthropods are characterized by their jointed characterized by their jointed appendages. These are how appendages. These are how they move. they move.

In some cases, arthropods In some cases, arthropods use wings for movement.use wings for movement.

DevelopmentDevelopmentMost insects develop starting as eggs. The eggs hatch in larvae which is Most insects develop starting as eggs. The eggs hatch in larvae which is the equivalent of a “baby.” Larvae transition into the adult stage through the equivalent of a “baby.” Larvae transition into the adult stage through metamorphosis—sometimes called molting—and become sexual active.metamorphosis—sometimes called molting—and become sexual active.

A prime example of this is the life cycle of butterflies which start as A prime example of this is the life cycle of butterflies which start as eggs, hatch into caterpillars, and then go through a stage of dormancy eggs, hatch into caterpillars, and then go through a stage of dormancy (known as Chrysalis) that eventually results in the butterfly. (known as Chrysalis) that eventually results in the butterfly.

Reproduction/ Life CycleReproduction/ Life CycleArthropods reproduce sexually. Male arthropods transfer Arthropods reproduce sexually. Male arthropods transfer sperm through sealed packets called spermatophores. sperm through sealed packets called spermatophores. The male can either lay it on the ground so that female The male can either lay it on the ground so that female arthropods will pick them up or the male can deposit the arthropods will pick them up or the male can deposit the packet directly into the female. packet directly into the female.

After the eggs become fertilized, they can hatch from After the eggs become fertilized, they can hatch from periods ranging from a few days to years. Most species of periods ranging from a few days to years. Most species of arthropods will lay the eggs in an external environment but arthropods will lay the eggs in an external environment but some species will hatch them internally. some species will hatch them internally.

The life cycle of an arthropod can range from a few weeks The life cycle of an arthropod can range from a few weeks to many years, depending the species.to many years, depending the species.

Specialized Tissues/FunctionsSpecialized Tissues/Functions

The exoskeleton of the Arthropod is built so that the hard section become The exoskeleton of the Arthropod is built so that the hard section become much thinner at joints. much thinner at joints.

Respiratory structures are specialized to adapt to the environment of the Respiratory structures are specialized to adapt to the environment of the Arthropod. For instance, lobsters have developed gills that allow them to Arthropod. For instance, lobsters have developed gills that allow them to survive underwater. survive underwater.

Land-based Arthropods develop air-conducting tubes known as tracheas.Land-based Arthropods develop air-conducting tubes known as tracheas.

In order to adapt to the environment, Arthropods have specialized In order to adapt to the environment, Arthropods have specialized sensory structures. Compound eyes are a prime example of this sensory structures. Compound eyes are a prime example of this occurrence.occurrence.

Interesting, but Unnecessary FactsInteresting, but Unnecessary Facts

Arthropods account for roughly 2/3 of all Arthropods account for roughly 2/3 of all known organisms. The estimated known organisms. The estimated number of Arthropods is around 1 billion number of Arthropods is around 1 billion billion (10billion (101818) )

Because both the Phylum Arthropod Because both the Phylum Arthropod and Phylum Annelids are segmented, it and Phylum Annelids are segmented, it was though for many years that both was though for many years that both shared a common ancestor. One of the shared a common ancestor. One of the prevalent hypotheses was that prevalent hypotheses was that Arthropods descended from Arthropods descended from Onychophorans (Walking worms). Onychophorans (Walking worms). However, recent study suggest that this However, recent study suggest that this is not the case and that they share is not the case and that they share common characteristics of bilaterians.common characteristics of bilaterians.

Cicada molting

*The process is sped up