EXTERNAL AND INTERNAL ANATOMY OF ARTHROPODS

Bilateral symmetrical body divided into segments (somites)
Paired, jointed appendages
Chitinous exoskeleton
Reduced body cavity (haemocoele)
Well-developed head, usually with compound eyes

What are the defining characteristics of arthropods?

3 distinct segments
2 distinct segments
No distinct segments

What are the different body segment classifications in arthropods?

chitin
protection, support, and prevention of desiccation

What is the exoskeleton of arthropods made of, and what is its function?

Eyes
Antennae
Mouthparts

What structures are found in an arthropod’s head?

antennae

Primary sensory organ (smell, taste, touch, and hearing)
Used for sizing prey, objects, or holding mates

Scape, Pedicel (Johnston’s organ), Flagellum

three segments of an insect’s antennae

Compound eyes
Ocelli

What are the two types of eyes in insects?

Compound eyes

Large, multi-faceted, used for detecting movement and color

Ocelli

Simple eyes, used for detecting light intensity

Labrum
Mandibles
Maxillae
Labium
Hypopharynx

What are the different mouthparts of an insect?

Labrum

Upper lip

Mandibles

Used for cutting, tearing, and chewing food

Maxillae

Manipulates food, contains sensory palps

Labium

Lower lip

Hypopharynx

Tongue-like structure, assists in food intake

Chewing (Biting) Type
Piercing-Sucking Type
Lapping (Siphoning) Type
Sponging Type

What are the different types of insect mouthparts?

Cockroaches, grasshoppers, beetles

insects with chewing mouthparts

Mosquitoes, bedbugs

insects with piercing-sucking mouthparts

Butterflies, bees

insects with lapping mouthparts

Houseflies

insects with sponging mouthparts

Prothorax
Mesothorax
Metathorax

What are the three sections of an insect thorax?

Prothorax

Bears the first pair of legs

Mesothorax

Bears the second pair of legs and first pair of wings

Metathorax

Bears the third pair of legs and second pair of wings

Cursorial
Saltatorial
Raptorial
Fossorial
Clasping

What are the modifications of insect legs?

Running

Cursorial leg modifications are for

Jumping

Saltatorial leg modifications are for

Seizing Prey

Raptorial leg modifications are for

Digging

Fossorial leg modifications are for

Grabbing/Climbing

Clasping leg modifications are for

Cockroach

give an example of an insect with cursorial leg

grasshopper

give an example of an insect with saltatorial leg

praying mantis

give an example of an insect with raptorial leg

mole cricket

give an example of an insect with fossorial leg

head louse

give an example of an insect with clasping leg

wings

Two membranes of cuticle supported by veins

Veins

this part of the wings provide structural support and species identification

Digestive system
Respiratory system
Excretory system
Reproductive organs

What major systems are housed in the abdomen?

Brain (Supraesophageal ganglion)
Subesophageal ganglion
Ventral nerve cord

What are the main components of an insect’s nervous system?

Brain (Supraesophageal ganglion)

Controls sensory organs

Subesophageal ganglion

Controls mouthparts

Ventral nerve cord

Contains segmental ganglia

Open circulatory system
Heart located dorsally
Blood is called haemolymph, and it does not transport oxygen

How is the insect circulatory system different from vertebrates?

Tracheal system
Open system
Closed system

How do insects breathe?

Tracheal system

Air enters through spiracles and is distributed via trachea and tracheoles

Open system

Air breathers (e.g., cockroaches)

Closed system

Aquatic insects use gills or plastrons

Foregut (Stomodaeum)
Midgut (Mesenteron)
Hindgut (Proctodaeum)

What are the three sections of the insect digestive system?

Foregut (Stomodaeum)

Food storage and grinding

Midgut (Mesenteron)

Nutrient absorption

Hindgut (Proctodaeum)

Excretion of waste

Malpighian tubules

Primary organ for waste excretion

Malpighian tubules

Removes nitrogenous waste and regulates water and salt balance