Introduction to Arthropods The Arthropods Introduction to Arthropods

Introduction over one million species most abundant of all visible animals live virtually everywhere can destroy crops and transmit diseases can produce valuable things like wax, honey, drugs, and silk help maintain crops by assisting in cross-fertilization control numbers of harmful arthropods engineers have improved machines by studying their design

Characteristics exoskeleton (protection and support) triple layer secreted by epidermis outer layer of proteins repels water and prevents water loss middle layer consists of protein and chitin inner layer similar to middle but provides more flexibility at the joints molts jointed appendages means of defense, sensory reception, chewing food, sexual reproduction

Characteristics body segmentation head thorax abdomen cephalothorax

Characteristics open circulatory system (depends on gravity) dorsal heart ventral nervous system antennae sensory bristles eyes compound (common) simple

Classification 4 Subphylum Trilobita (extinct) Crustacea Chelicerata Uniramia 20 Classes primary characteristics that separate the groups are body division number and kinds of appendages means of respiration

Subphylum Crustacea lobsters, crayfish, shrimp, crabs, pill bugs, barnacles

Life Processes of the crayfish

Life Processes: Crayfish movement muscles legs swimmerets flipper-like appendages four pairs of walking legs

Life Processes: Crayfish scavengers nutrition ingestion digestion esophagus, anterior portion of stomach gastric mill posterior portion of stomach digestive glands intestine, anus

Life Processes: Crayfish respiratory two sets of feathery gills gills allowed for flow of oxygenated water can store water for walking on land circulation open system pericardial sinus (stores blood, surrounds heart) dorsal heart sternal sinus (passes blood to gills) excretion green glands filter out waste fluid excreted through a pore anterior to the mouth

Life Processes: Crayfish heart pericardial sinus sternal sinus

Life Processes: Crayfish green gland

Life Processes: Crayfish response ventral nervous system sensory organs compound eyes antennae & antennules tiny bristles statocyst (organ of balance)

Life Processes: Crayfish reproduction regeneration for repair only sexual with separate sexes mate in the fall, female stores sperm until spring when she lays eggs “in berry” molting (seven times during the 1st year)

Subphylum Chelicerata “claw”

Subphylum Chelicerata Class Arachnida spiders, scorpions, ticks, mites

Class Arachnida (most recognized) Characteristics that distinguish them from the insects four pairs of walking legs two body parts cephalothorax abdomen no antennae or mandibles

Class Arachnida respiration through book lungs usually four pairs of simple eyes book lungs

Spiders largest and most familiar group in the class six pairs of appendages (no antennae) chelicerae poisonous fangs pedipalps sensory reception transfer of sperm in male

Spiders silk production spinnerets uses capturing food reproductive purposes

Spiders separate sexes female often larger male transfers sperm to ventral surface of female some type of “courtship” like offering of food some females eat male after mating

Spiders black widow brown recluse tarantulas other arachnids scorpion mites ticks

The word root “-poda” means head. foot. flat. pore. BJU PressArt, biology textbook, pp. 369

The exoskeleton of the arthropods is made up of cellulose. chitin. bone. lime. BJU PressArt, biology textbook, pp. 369

The single exoskeletal plate that protects the cephalothorax is the carapace. mantle. mandible. gastric mill.

Chitinous teeth line the stomach of the crayfish and help to grind up food. true false

The respiratory organs of the crayfish are the green glands. gills. lungs. epidermis.

Although crayfish have an open circulatory system, some arthropods have a closed system. true false

The cavity that surrounds the heart of the crayfish is the sternal sinus. cardiac cavity. pericardial sinus. dorsal cavity.

The excretory organs of the crayfish that remove soluble wastes from the blood are the green glands. intestines. kidneys. anus.

A sac that helps the crayfish keep its balance is the ganglion. brain. antennule. statocyst.

The crayfish can reproduce asexually. true false