ARTHROPODA

5 Interesting Facts about Arthropoda

• Making up more than 80% of all animals;

• When a tarantula is angry, it will pull off some of its hairs and throws them to its prey;

• A cockroach can live for 5 days after its head is removed;

• A dragonfly is able to fly at a speed of 30 mph;

• Total weight of arthropoda is more than the other animals combined.

ARTHROPODA - GENERAL

• The name means jointed legs;• Most successful of all animals;• Represents 80% of all animals;• > 1 million spp. Already identified (estimate 6 – 9

million);• Habitat: deep oceans – highest mountains;• Size:

– Biggest: ‘king crab’ (12 feet including legs)– Small: example: copepoda

ARTHROPODA - CHARACTERISTICS

– Bilateral symmetry;– Body divided into 3 sections;

• head (made up of 6 segments)• thorax• abdomen

some groups: (eg prawn with cephalothorax)

– Outer segmentation only (no septa)– Jointed appendages

• 1 or 2 pairs per segment,• Sometimes modified for specific task• Joints allow easier and faster movements.

ARTHROPODA – CHARACTERISTICS(cont)

– Exoskeleton made of chitin• Terrestrial sp: exoskeleton layered with wax – protection

from dehydration• Removed from time to time;• Disadvantage – heavy – modified in flying spp.

– Molting• New exoskeleton formed prior to molting;• During molting, abdominal muscle contracts and fluid

moves to the anterior region; • Head expand, causing exoskeleton to split.

ARTHROPODA – CHARACTERISTICS (cont)

– True coelom reduced during adult stage;• During adult stage almost entire body cavity becomes a

hemoecel filled with blood;

– Complete digestive system: mouth, enteron and anus;

– Open circulatory system : dorsal heart, artery and messenchyma blood cavity (sinus)

– Respiration by absorption (body surface), trachea (air tubes), book lungs, gills;

– Excretory system – green gland (crayfish) or Malphigian tubules (Insecta)

CIRCULATORY SYSTEM – LOBSTER

Respiratory System of Prawn

TRACHEAL SYSTEM - Insecta

Trachea - grasshopper

Green Gland of Crayfish - excretion

EXCRETION IN INSECTA

• Malphigian Tubule– Folding of intestine forming a pouch;– Pouch bathed with blood in hemoecel– Waste materials absorbed and moved into

pouch and removed through intestine

• Waste Material – uric acid

ARTHROPODA – Classification

• Subphylum Trilobita

• Subphylum ChelicerataClass Merostomata (horse-shoe crab)Class Arachnida (spiders)

• Subphylum Mandibulata– Class Crustacea (shrimp, copepoda)– Class Diplopoda (eg millipedes)– Class Chilopoda (eg centipedes)– Class Insecta (insects)

ARTHROPODA – Classification (cont)

• Subphylum Trilobita - extinct

ARTHROPODA – Classification (cont)

• Subphylum Chelicerata– First pair of appendages – celicera (with

claws)– Second pair – padipalp– No antenna

Class Merostomata (horse-shoe crabs)

Class Arachnida (spiders)

Subphylum: Chelicerata

Class Merostomata (horse-shoe crabs) - 5 spp. still exist;

- marine animal

- Hard shell to protect cephalothorax; - feed on small invertebrates;

- second pair appendages resemble legs

- respiration – book lung

Subphylum: Chelicerata

Class Arachnida -

Scorpion(Scorpionida)

Spider(Araneae)

Tick (Acari)

Subphylum: Chelicerata

Class Arachnida

- almost 100,000 spp identified

spider (50,000)

ticks and mites (48,000)

scorpion

- respiration – trachea, book lung

Subphylum: Mandibulata

–Class Crustacea (shrimps, crabs,

copepoda)

–Class Diplopoda (millipedes)

–Class Chilopoda (centipedes)

–Class Insecta (insects)

CLASS CRUSTACEA

• Estimated 30,000 sp• Most aquatic (especially marine)• 2 pairs of antennae• 1 pair of mandible• 1 pair of compound eyes• 1 pair appendages per segment• Most body – head, thorax, abdomen• Repiration: gills• Exoskeleton : hard but flexible

Class Crustacea

Sub-class:

copepoda

branchiopoda

ostrocoda

branchiura

thecostraca

malacostraca

Sub-Class Malacostraca

Phyllocarida(sea fleas)

Stomatopoda

Decapoda

(crab, shrimp/prawn)

Peracarida

(amphipod, isopod,

mysids)

Euphausiacea

Class Diplopoda (millipede)

about 8000 sppHead

a pair of antennaea pair of mendible

Respiration – tracheaFeeding –

herbivours, scavenger

Many with poison gland

CHILOPODA (Centipede)

• About 5000 sp• Terrestrial• Carnivour/predator• Food: small arthropods• A pair of antennae and

mandibles• A pair of legs per segment• With poison gland

CLASS INSECTA (INSECTS) - Characteristics

• 1 million spp identified (estimate few millions)• Most successful group• Habitat: almost all terrestrial and fresh water• A few marine spp• Body: 3 tagmata – head, thorax and abdomen• Big compound eyes• A pair of antennae• 2 pairs of wings• 3 pairs of legs (for walking)• Mouth parts (depending on food)• Respiratoion: trachea, gills• Excretion: Malphighian tubule

CLASS INSECTA (INSECTS) – Charact (cont)

• Reproduction:– Separate sex– Fertilization only once (sperm stored by female)– Use pheromone

• Growth– Special characteristics– Some: egg juvenile (resemble adultl)

molting grow adult

– Most: egg larva pupa adult

INSECTA

SUBCLASS APERYGOTA (No wings)

Order Thysanura – silverfish

INSECTA

SUBKELAS PERYGOTA (with wings)SUPERORDER EXOPTERYGOTA (incomplete

metamorphosis)

Order Isoptera (white ants)• Order Odonata (dragonfly)• Order Blattaria (cockroach)• Orthoptera (grasshopper)• Order Mantodea (praying mantis)

INSECTA

SUBCLASS PERYGOTA (with wings)SUPERORDER ENDOPTERYGOTA (complete

metamorphosis)

• Order Lepidoptera (butterfly)• Order Diptera (house fly, mosquito)• Order Coleoptera (beetle)• Order Hymenoptera (ants, bees)

SUPERORDER EXOPTERYGOTA (incomplete metamorphosis)

Odonata - dragonfly

Orthoptera -grasshopper

SUPERORDER EXOPTERYGOTA

Mantodea – praying mantis

Blattaria – cockroach

SUPERORDER ENDOPTERYGOTA – complete metamorphosis

Hymenoptera – ants, bees, and hornets

- Membranous wings;

- 2 pairs of wings

SUPERORDER ENDOPTERYGOTA

Diptera – housefly

- a pair of wings

- second pair much reduced

SUPERORDER ENDOPTERYGOTA

• Coleoptera – (sheath)• Hard front wing pair

• Lepidoptera – scaly wings