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Characteristics in the Phylum

Arthropoda

The segmented bodies happen to be arranged in

regions, named tagmata (e. g., brain, thorax,

abdomen).

The combined appendages (e. g., lower limbs, antennae)

are jointed.

They posses a chitinous exoskeletion that

has to be shed during growth.

They may have bilateral symmetry.

The worried system is hinten (belly) plus the

circulatory method is open and ventral (back).

Arthropod Teams (taxa)

The arthropods will be divided into two

large teams that exist today:

The Chelicerates

and

The Mandibulates

Exoskeletons

• Durability and

impermeability

• Resolves difficulties of

life in land:

– desiccation

– need for structural

support

• BUT: must molt to

grow (ecdysis)

Grasshopper molting

Phylum Arthropoda " arthropods”

• > 1 mil spp., many of them insects (most of those,

beetles)

• Most diverse, broadly distributed & abundant coming from all

animal phyla

Arthropod innovative developments

• Exoskeleton of chitin

* Hard & good

* Gabardina to normal water

* Molting

• Segmentation

• Jointed appendages

Millipede

* " jointed feet”

• successful walking &

swimming

2. wings in many

• certainly one of 2 phyla to take flight

Monarch butterflies metamorphosis

Arthropod limbs

• Two types, relating to feeding function

* Uniramous, single branch

* Biramous, two branches, sometimes gnathobasic

(like in Limulus plus the trilobites)

* Some question cast just lately on this simple scheme!

Trilobite gnathobasic hands or legs

Further arthropod anatomy

• Extensive cephalization (sense bodily organs & mouth area parts)

• Well developed

sense organs:

* " Taste”

* Sight many

with complicated,

compound

eye

Segment blend

Abdomen

Antennae

(sensory

reception)

Head Chest

Swimming

appendages

Walking thighs

Pincer (defense) Mouthparts (feeding)

Some Arthropod groups

Trilobite (extinct group)

Limulus

Millipedes

and

centipedes

Class Arachnida

" Bots, mites, ticks, scorpions”

40 µm

• 6 pairs of appendages

• which includes 4 pairs of jogging legs

Class Crustacea

" Crabs, prawn, barnacles”

Lobster

Goose-neck barnacles

• Mainly

marine

• Carnivores,

detritus feeders,

filter feeders

• 2 pairs of

antennae

• 3 or maybe more

pairs of

mouthparts

• 3 or maybe more

pairs of legs

Prawn on coral reefs

Cf Fig 33. 38

Classes of Crustacea

(mostly marine, fresh water, a few terrestrial)

(all include two pair of antennae, five or more pairs of legs,

segmented belly appendages, mind & trunk area or

cephalothorax & belly body agreement, have gills)

Isopoda - sowbugs or perhaps pillbugs

Amphipoda - fine sand fleas, amphipods

Cirripedia - barnicles

Decapoda - crabs, lobster, shrimp

several other small orders

Crayfish cephalothorax

(Decapoda)

Sowbug (Isopoda),

a terrestrial crustacean

Category Insecta -- Insects

Fig 33. thirty-five

Joined segments in to 3

body system regions:

* Head

5. Thorax

2. Abdomen

Evolution

Flight

21 Orders

By numbers and

influence, one of the most

important phylum of

creatures

Chelicerate Arthropod Characters:

Pincher-like mouthparts chelicerae - and pedipalps

ZERO antennae

Two body areas, usually cephalothorax & stomach

Four pairs of hip and legs

Horseshoe crabs and arachnids

are only living groups

Mandibulate Arthropod Characters:

Mouthparts happen to be mandibles normally chewing sideways

One or two pairs of antennae

Various physique region plans cephalothorax & abdomen / head & trunk / head, thorax & stomach

Variable leg numbers

Pesky insects, crustaceans & myriapods

Instructions of Arachnids

Scorpionida -- scorpions

Pseudoscorpionida - fake

scorpions

Opiliones - daddy-long-legs or

harvestmen

Acari - mites & ticks

Araneida - bots

Pseudoscorpion

Scorpion

Daddy-long-legs

Tick

(a mite)

Wolf

Index

Scorpion Structure

chelicerae

eye

pedipalp

Pseudoscorpion

Mite and Tick Body system Regions

pedipalps &

chelicerae

cephalothorax

belly

American doggie tick male

Blacklegged (deer) tick girl

American doggie tick...