Phylum Arthropoda

1. Phylum Arthropoda –means “jointed feet”

2. Characteristics

a. Segmented bodies

b. Jointed appendages

c. Exoskeleton

• Appendages – limbs that extend off the main body section of an organism.

• Exoskeleton – tough external covering that protects and supports the body , made of chitin.

• Chitin – Protein and a carbohydrate that makes the exoskeleton strong.

1). 3 layers of the exoskeleton

a) Outer – waxy, repels water.

b) Middle – Hardened by tough additional calcium.

c) Inner – Muscle attachment, flexible at joints, chitin.

2. Feeding

A. Very Diverse – filter feeders, detritus feeders, carnivores, herbivores, blood suckers.

3. Antennae – feelers, sense appendages.

4. Compound Eyes – multiple lens, seeing multiple images.

5. Respiration A. Aquatic species breathe through gills.

1. Feathery structures that diffuse oxygen from the surrounding water.B. Horseshoe crabs breathe through book gills.C. Arachnids breathe through book lungs.D. Terrestrial arthropods breathe through tracheal tubes.

1. Tubes that transport oxygen.6. Open circulatory system7. Well developed nervous system and sense

organs.

8. Molting – a process induced by hormones

A. Shedding its skin covering and manufacturing a larger one. This may occur multiple times so it may reach its mature size.

B. New skin is soft and animal is vulnerable and hides until it hardens.

9. Metamorphosis allows the arthropod to change shape and form a new body structure changing many aspects of it prior life.

Arachnids

10. Subphylum Chelicerata

2 classes (Aracnids and Merostomata)

A. Examples – spiders, mites, ticks, scorpions, and horseshoe crabs.

B. Body is divided into 2 parts:

cephalothorax and abdomen.

C. Chelicerae are specialized mouthpart called fangs, used to stab and paralyze prey.

D. Pedipalps – longer than chelicerae, and are mostly used to grab prey.

Chelicerae

Pedipalps

E. Class Arachnida – Spiders, mites, ticks and scorpions.

• A. Cephalothorax – Head and Thorax combo.• B. Abdomen- Last section• C. Chelicerae – modified fangs• D. 8 simple eyes• E. 4 pairs of legs attached to the cephalothorax• F. Spinnerets – web weaving organ

– 1) webs, homes, capture food, store food– 2) Ballooning – young use silk to fly away

from nest to relocate.

• G. Book lungs- paired sac with folds that increases surface area for respiration.

• H. Trachea – some spiders have this tube that carries oxygen directly to tissues.

• I. Spiracles – Holes in abdomen that attach to trachea that allow oxygen to enter.

• J. Malpighian tubules – excretory organs that extract waste from the blood and transport it to the feces.

• K. Coxal Gland – another excretory gland in some spiders that discharge waste through openings at the base of some legs.

Camel Spider

Crustaceans

11. Subphylum CrustaceaA. Examples – crab, lobster, shrimp, crayfish, types of plankton, barnacles (sessile existence) rolly pollies.B. Nauplius – Free swimming larvaeC. Two pairs of antennaeD. Several pairs of mouthpartsE. Branched appendagesF. Mandibles are specialized pair of mouthparts, used for biting and grinding.

A. External

1. Cephalothorax- Combo. Head/thorax covered by the carapace.

2. Abdomen - tail

A). Telson – 7th single segment, flat paddle, posterior end.

B). Uropod – 6th paired seg. Helps propel crayfish in a tail flip. (backwards movement)

3. Antennules- Feelers, touch, taste, and equilibrium.

4. Antennae – feelers, touch and taste.

12. Anatomy of a crayfish

5. Maxillae – manipulate food, respiration. (create a water flow)

6. Maxillipeds – 3 pairs, manipulate food.7. Mandibles – jaws for chewing and

crushing.8. Chelipeds – large claws, food and defense9. Walking legs – 4 pairs10. Swimmerets – appendages attach to

abdomen used to hold eggs during reproduction.( also create a water flow to aerate the eggs)

13. Crayfish systems

A. Digestion – stomach contains small teeth to grind food that enters.

B. Respiration – Gills that extend from the base of the walking legs. Water is circulated as it walks pushing it over the gills.

C. Circulation – Open system, heart pumps hemolymph.

D. Excretion – Green glands found at the base of the antennae release excess water.

E. Nervous system – pair of ganglia

F. Statocysts – Cells that contain particle of calcium that move when the crayfishes body is upside down, The movement of these particle alerts crayfish to flip itself back right side up.

•Chilopoda and

Diplopoda

14. Subphylum Uniramia –Centipedes, millipedes and insects.

A. Class Chilopoda1. Centipedes

a). One pair of leg per segmentb). Flattened bodyc). Pair of poisonous claw-like

appendages that inject venom into it’s prey

d). Nocturnale). Carnivore

B. Class Diplopoda1. Millipede

a) Two pairs of legs per segment.

b) Rounded body

c) Eat during the day light

d) Release chemical toxin when curled up.

e) Herbivore