Ch. 36 - Arthropods

Ch. 36 - ArthropodsPhylum: Arthropoda

Means “jointed legs”

75% of all animals belong to this phylum

Insects, lobsters, crabs, spiders, millipedes, & centipedes

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Characteristics of Arthropods1. Appendages – legs, antennae

2 appendages per segment2. Open circulatory system3. Digestive system4. Ventral nervous system5. Exoskeleton – protection & desiccation

Made of chitinVideoVideo

What is molting?

Shedding of the exoskeleton

Why do animals molt?

Every time an animal molts it enlarges or grows

What are some advantages & disadvantages of molting?

Protection, prevents desiccation

Must molt to grow, vulnerable after it molts

Crustacea subphylumCrayfish, lobsters, crab, sow bugs, daphnia.Mainly aquaticCrayfish Characteristics

2 main body parts1. Cephalothorax – head & thorax2. Abdomen – 7 segments•Last segment is the telson

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Appendages of the Crayfish1. Chelipeds – pinchers

2. Antennules – smaller (inside)

3. Antenna – larger (outside)

4. Walking legs – 4 along the thorax

5. Swimmerets – along the abdomen

6. Uropod – outside the telson

Digestive & Excretory SystemsFirst the crayfish tears the food with their maxillae & maxillipeds.They chew their food with their mandiblesThe food passes through the esophagus to the stomach.

The digestive glands absorb nutrients, then the undigested material enters the intestine, and then exits the anus.

Green glands are also used in the excretory system to remove waste; much like kidneys.

Circulatory & Respiratory SystemsOpen Circulatory System

Dorsal heart that pumps blood to the body cavity to bath the organs. It is then pumped to the gills.

What do the gills do?

Large surface area for gas exchange

The gills are attached to each walking leg

Nervous SystemVentral nerve cord

Brain

Sense receptors antennules, antennae, & compound eyes

A compound eye has many lenses

Do you have a compound eye?

Reproductive SystemUsually mate in the fallThe male uses its swimmerets to transfer sperm to the female, where she keeps the sperm until spring.The eggs are then fertilized and kept along the female’s swimmerets until they hatch.

Chelicerae - subphylumClass: ArachnidaSpiders, mites, scorpionsMany use stingers or fangs with poison.How do spiders catch their prey? with webs or “trap doors”Scorpions hunt at night and hide during the day.Video

Only a few scorpions are poisonous enough to kill humans.

Mites and ticks are the most abundant in this class.

Ticks are parasitic and some carry diseases.

Lyme’s disease

Rocky mountain spotted fever.

Spider mites can damage and wipe out fruit trees or other trees.

Structure of a spider2 segments

1. Cephalothorax

2. Abdomen

Chelicerae – hollow fangs

Pedipaps – aid in chewing

8 legs & eyes

Spiracles – openings for respiration

Book lung – air sacs in the abdomen for respiration.Malpighian tubules – kidney-like excretory system. Removes wastes.Spinnerets – spins silk for webs

Can also be used as silk balloons to fly away in young spiders.

Black widow & Brown Recluse2 poisonous spiders in Kansas

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Uniramia - subphylum2 classes1. Diplopoda – millipedes

Means “thousand feet”2 pair of legs per segment

2. Chilopoda – centipedesMeans “hundred feet”1 pair of legs per segment Some are poisonous

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Insects – 2nd Part of Ch. 39Most diverse and largest number of species of any class of organism.

They were present on earth before the dinosaurs, over 300 million years ago.

Differences from other arthropods

1. 3 body segments head, thorax, abdomen

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2. Head has 1 pair of antennae

3. Thorax has 3 pairs of legs & 1 or 2 pair of wings.

4. No wings or legs attached to the abdomen.

Kingdom: Animalia

Phylum: Arthropoda•Class: Insecta (700,000 + species named)

What makes insect so successful?

Lots of them – adapt very well

Great diversity – several types

Reproduce rapidly

Small size & ability to fly (most)

Benefit of insects?1. Pollination – plants can’t reproduce without insects. We need plants to survive.2. Food – for other animals. Several animals rely on insects as a source of food.3. Industrial uses – silk & honeyWhat is the study of insects called? (E.C)

Entomology

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Grasshopper External Structures3 Body Parts:1. Head

Labium – grasps the food ( bottom lip)Mandible – chews the food (jaws)Labrum – holds the food (upper lip)Maxilla – extra jaws

2. Thorax3 pairs of legs (6 total)2 pair of wings usually

3 parts to the thorax

1. Prothorax – pair of walking legs

2. Mesothorax. – pair of walking legs

3. Metathorax – pair of jumping legs

Forewings are attached to the mesothorax

Hindwings are attached to the metathorax

3. Abdomen

Spiracle – for respiration

Tympanum – for hearing (eardrum)

Ovipositors – holds it eggs

GrasshopperInternal StructuresDigestive System

What do grasshoppers eat?

What are the mouth parts?

Food passage: esophaguscrop (storage) gizzard (grind) midgut (digested) hindgut (rectum & colon) out the anus

Circulatory System

Open Circulatory System

An aorta is a large vessel that carries the blood on the dorsal side.

2 Hearts along the aorta

Respiratory System

No lungs or gills

Use spiracles – openings along the abdomen

The spiracles lead to the trachea

Nervous System

Brain connected to a ventral nerve cord

Has simple and complex eyes

Have antennae

Tympanum for sensing sound

Reproductive System

The male deposits sperm into the seminal receptacle, which stores the sperm.

The female uses its ovipositors to deposit her eggs in the ground.

Types of MetamorphosisIncomplete Metamorphosis

1. Egg

2. Nymph – immature form of an adult

3. Adult – able to reproduce (wings)

Complete Metamorphosis1. Egg2. Larvae – catepillar stage3. Pupa – cocoon protects the pupa4. Adult – emerges from the pupa (butterfly)

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Defenses of InsectsWhat ways do insects use defenses?1. Stinger or bite – bee, wasp, ants2. Camouflage – blend into their surroundings.

Ex. Grasshopper, praying manthesisVideo

3. Warning coloration – alert other animals that the insect might be poisonous.

Insect BehaviorDivision of Labor among Bees1. Worker bee – female bees, most abundant. (8,000) - sterile2. Drone – male bees (100)3. Queen bee – the only fertile femaleCHARACTERISTIS OF EACH BEEVideo

The worker bee produces royal jelly to feed the queen bee

The worker also secretes wax to make the hive.

The produces a pheromone called queen factor, which makes the other females sterile.

Round Dance – tells the other bees food is within 50 meters

Waggle Dance – tells the other bees food is greater than 50 meters.