T1 ARTHROPODS - DISTINGUISHING FEATURES OF INSECTS AND ARACHNIDS

T1 DISTINGUISHING FEATURES OF INSECTS AND ARACHNIDS

Another term for arthropods

PHYLUM ARTHROPODA

arthropods

animals with jointed or segmented body and appendages.  They are characterized by external skeleton consisting mostly of chitin, and a segmented body where individual segments are often fused together

tagmatization

individual segments are fused together

4 main characteristics of arthropods

• Bilaterally symmetrical animals

• Segmented body

• Paired jointed appendages

• Development is complete or incomplete. The life

history may include different forms (egg to adult)

Arthropods exoskeleton are?

flexible and chitinous

when the males and females of the same species have very different characteristics

sexual dimorphism

Arthros means

joints

Podos means

foot

Poda means

feet

Segments

divisions or sections of the body and appendages, and each segment could be detached cleanly from another or from where it is attached.

Appendage

a structure with one end attached to body and the other end is dangling (e.g. antenna, legs, wing, etc)

5 subphylas of arthropoda

• Hexapoda

• Chelicerata

• Crustacea

• Trilobitomorpha

• Myriapoda

Insects

Hexapoda

spiders, scorpions, horseshoe crab, mites and ticks

Chelicerata

Trilobites

Trilobitomorpha

Crabs, Shrimps, Lobsters, pillbugs, barnacles

Crustacea

Millipedes and centipedes

Myriapoda

Trilobitomorpha

All are extinct and preserved as fossils. Formerly numerous marine animals

Crustacea

terrestrial, fresh water or marine animals.

2 segments of a crustacean

head + pereon and pleon

Myriapoda

These are terrestrial and air-breathing arthropods. Their body is made of many similar segments.

Has more than 11 pairs of legs

Myriapoda

2 segments of myriapods

head and trunk

Chelicerata

Their body is divisible into anterior prosoma (Cephalothorax) or head (Gnathsoma), and abdomen (posterior opisthosoma) or (idiosoma)

2 classifications of chelicerata

arachnids and merostomata

Arachnids

• Two body regions (head=cephalothorax and abdomen)

• Cephalothorax with 6 pairs of appendages (chelicerae, pedipalps and 4 pairs of

walking legs)

• Abdomen with up to 3 pair of appendages (spinnerets)

• Mostly terrestrial and predatory, some secondarily aquatic and sap-sucking

What do spiders have that mites dont?

pedicel

pedicel

a slender waist separating the cephalothorax and the abdomen.

Segments of a spider

cephalothorax and abdomen

2 segments of a mite

gnathsoma and idiosoma

Hexapoda

Insecta. These are terrestrial and aquatic arthropods. Body is divided into 3 distinct regions (head, thorax, and abdomen).

the dominant terrestrial animal life on Earth.

insects

they are well over 1 million different known species of insects in the

world, and some experts estimate that there might be as many as 10 million.

Insects

Only invertebrates with wings and only animals with true wings

Insects

Characters of Arthropoda

mostly aquatic, wit 2 body regions and 5-7 pairs of legs

crustacea

terrestial, with a flat or round body, more 11 pair of legs and has 1-2 pairs of legs per body segment, has 2 body regions

myriapoda

has 4 pair of legs with 6-8 simple eyes and no antennae, with 2 body regions

chelicerata

has spinnerets and can produce silk, no antennae

arachnids

3 body regions, 3 pair of legs. 1 pair of antennae and may have wings

hexapoda