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Arthropods Chapter 31

• Diversity of Arthropods

–Arachnids

–crustaceans

–Centipedes and Millipedes

–Insects• What is an Arthropod? • Characteristics of Arthropods

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Diversity of Arthropods• Arachnids

• Crustaceans

• Centipedes / Millipedes

• Insects

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What is an Arthropod?

• Characteristics of Arthropods

–Invertebrate

–bilateral

–exoskeleton

–appendages

(jointed Appendages)

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Segmentation in Arthropods

• Head

• Thorax

• Abdomen

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Body Segment fused

• Cephalotharax

• Abdomen

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Exoskeleton

• Success of group attributed to this features

• hard thick outer layer made of protein called chitin

• Used as armor protection and support for muscle attachments

• Problems with exoskeleton

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Jointed Appendages

• Multiple uses:

senses, walking, feeding

and mating• Joints allow more powerful

movement• allow appendages to be used in

multiple ways

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Why they must Molt?

• Exoskeleton is heavy and bulky

• restricts speed of movement

• require that the exoskeleton be shed to allow growth (molting)

• During molting which may require a lot of time the animal is vulnerable

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Gas Exchange

Book Lungs

Gills

Tracheal Tubes

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Arthropod Senses

• Movement, sound, or chemical can be detected by ANTENNAE - pheromomes

• Detect light with SIMPLE EYES

• Motion and some colors are detected by the COMPOUND EYES

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Nervous System

• Well developed :

– double ventral nerve cord,

– anterior brain,

–several ganglia - each segment has a set to help control the functions

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Complex body systems• Open circulatory system bathes the

organs• Complex digestive system• Mouth parts have a great variety

–holding

–chewing

–sucking/ biting• Waste removed by malpighian tubules

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Sucking mouth parts

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Butterfly mouth part

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Bee mouth part

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Spider Fangs

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More Spider fangs

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Reproduction

• Sexual reproduction

• Some are hemaphrodites

• Parthenogenesis

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Luber Grasshopper

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Walking Stick

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Special Mouth Parts

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Butterfly

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Crayfish’s External anatomy

-cephalothorax - swimmeret

- abdomen - uropods

-Walking legs - mouth parts

-claws(cheliped) mandible

-antenna maxilla

-antennules maxilliped

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Crayfish’s Internal anatomy

• Digestive Circulatory

– Esophagus - open system

– stomach heart

• grastric mill dorsal artery

– intestine

– anus

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Crayfish’s Internal Anatomy 2

• Respiratory system– Gills– legs– bailers

(maxilla)

• Excretory sytem– green gland– green gland pore

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Questions A (100 words each)

1.Compare the digestive, respiratory, and reproductive system of Arachnids and Grasshoppers

2. What are 5 anatomical characteristics that only Arachnids have?

3. How do joints affect the speed and power an animal has?