BIO 225: Arthropods

4 General characteristics of arthropods

1. Defining Characteristic

2. Diverse?

3. Symmetry?

4. Protostomes or Deuterostomes

1. Jointed foot

2. Great diversity

3. Bilateral symmetry

4. Protostomes

What 4 main factors make arthropods so diverse and abundant?

1. Versatile exoskeleton

2. Efficient locomotion

3. Open circulatory system

4. Great sensory system

What is the Arthropods way of distributing blood throughout their body?

Diffusion

Phylum Arthropoda: General outline of Phylum, subphyla, classes, and orders

Phylum Arthropoda

• Subphylum Trilobita

• Subphylum Chelicerata

  • Class Arachidna

    • Orders: Spiders, harvestmen, ticks and mites

• Subphylum Myriapoda

  • Class Chilopoda

  • Class Diplopoda

• Subphylum Crustacea

• Subphylum Hexapoda

  • Class Insecta

    • Orders: Lepidoptera, Hemiptera, Odoanata, Ceoeloptera, Hymenoptera, Orthoptera, Diptera

Phylum Arthropoda 5 subphyla

Trilobita, Chelicerata, Myriapoda, Crustacea, Hexapoda

Subphylum Trilobita 3 general characteristics:

1. Extinct

2. Found in ocean as fossils

3. Chiton-like

What (externally) separates Trilobites from Polyplacophorans?

Trilobites have antennae, more than 8 plaques, and legs

Subphylum Chelicerata general characteristics

1. Antennae?

2. Appendages?

3. Organism covered?

1. No antennae

2. 6 pairs of appendages

   1. 1st pair chelicerae (fangs)

   2. 2nd pair Pedipalps (grasping and sensing)

   3. 8 walking legs

3. Horseshoe crab

Do Chelicerata have antennae?

No

What types of appendages do Chelicerata have? How many pairs?

They have 6 pairs of appendages. The 1st pair are the Chelicerae (fangs), the 2nd pair are the Pedipalps (mating), and the rest are their 8 walking legs.

What subphylum would the Horseshow crab be found in?

Subphylum Chelicerae

What medically beneficial thing do Horseshoe crabs offer?

Their blood

What does Horseshoe crab blood do? What is it used for?

Contains endotoxins from bacteria, allowing it to kill bacteria, and serves sterilizes small pieces of bacteria; Used to sterilize medical equipment and products.

Subphylum Chelicerata, Class Arachnida organism covered

Spiders

What is the subphylum for spiders? What is the class?

Subphylum Chelicerata, Class Arachnida

Spider internal structure

1. Cephalothorax (1st segment)

2. Abdomen (2nd segment)

3. Simple eyes (detect motion)

4. Compound eyes (detects shape)

5. Pumping stomach (feeds on liquids)

6. Silk gland (silk)

What are the two major body segments in spiders?

1. Cephalothorax

2. Abdomen

2 kinds of Spider eyes and what they detect

1. Simple eyes (motion)

2. Compound eyes (shape)

What kind of stomach do spiders have? What does it do

A pumping stomach; it pumps liquified food through the gut for digestion

Spider silk is used for what?

Used to coat surgical instruments, implants, and catheters.

Spiders use their silk for:

Webbing, egg sacs, and drag lines

What structure in spiders is important for reproduction?

Pedipalps

Reproduction in spiders

Male spiders transfer sperm packets (spermatophores) to the female using clubbed pedipalps

What organism has Sexual dimorphism? What does this mean?

Spiders; You cannot externally differentiate the male and female

Venomous spiders in US

1. Black widow

2. Brown Recluse

Black widow pattern

Hourglass

Black widow venom contains what and causes what when they bite you?

A neurotoxin that releases a lot of Ach; causes uncontrollable muscle contractions

Brown recluse pattern

Violin-shaped pattern

The Brown Recluse causes what when they bite you? What happens?

Hemolytic necrosis; death of the tissue in the area where one is bitten

If spiders are big enough, they can eat what?

Small animals

Harvestman are also called what?

Daddy-long-legs

Harvestmen have how many body segments? What are they?

They have one body segment; their legs

Ticks and mites 2 general characteristics

1. Cephalothorax and abdomen are fused

2. Mouth parts are projected forward (anteriorly)

In ticks and mites the _________ and _________ are fused.

Cephalothorax, Abdomen

What segment are legs usually found in on ticks and mites?

The cephalothorax

Demodex are also called what?

The follicle mite

Where do Demodex (follicle mites) live and what do they eat?

They live on eyelashes or hair follicles; they eat dead skin cells

Chiggers (larva)

1. What do the larva cause?

2. Where can you find them?

3. How do they feet and what do they eat?

4. What happens when the larva mature?

5. What do the adults eat? What do adults NOT eat?

1. Causes itching;

2. usually find them in areas where clothing is tight.

3. Inserts tube into skin and eats skin cells.

4. They fall off and the tube remains.

5. Adults eat small arthropods, they DO NOT feed on humans like the larvae.

What disease passed by ticks causes rashes and high fevers?

Rocky Mountain Spotted Disease

Rocky Mountain spotted disease

1. Vector: ticks

2. Causes: rashes and high fevers

What disease passed by ticks causes a Bull’s eye-patterned rash on the skin?

Lyme Disease

What is the characteristic rash pattern caused by Lyme Disease?

Bull’s eye pattern

What bacteria causes Lyme Disease?

Borrelia burgdorferi

Main vector of Lyme Disease

Deer tick

How do deer ticks transfer bacteria to the host?

Borrelia reproduce inside the ticks body and then is transferred to the host through its saliva.

Deer ticks are also called what?

Blacklegged ticks

For deer ticks, both the ______ and _____ stages can infect the host

Nymphal, Adult

Main host of deer tick

White-footed mouse

What common diseases do ticks cause?

1. Rocky Mountain Spotted Disease

2. Lyme Disease

Lone star tick pattern; which gender is it found on?

White spot on the female’s body

The lone star tick can trigger what?

It can trigger an allergic reaction to red meat

Subphylum Myriapoda general characteristic?

Many legs

Subphylum Myriapoda 2 classes

1. Chilipoda

2. Diplopoda

Class Ciliopoda 5 general characteristics

1. Organisms?

2. Carnivorous or herbivorous?

3. Fast or slow moving?

4. First body segment contains

5. How many legs per segment?

1. Centipedes

2. Generally carnivorous

3. Fast-moving

4. 1st body segment contains venomous claws/fangs

5. 1 pair of legs per body segment

Class Diplopoda 5 general characteristics

1. Millipedes

2. Generally Herbivores

3. Slow-moving

4. Defense involves curling up into ball and contains poisonous repellent fluid

5. 2 Pairs of legs per body segment

Subphylum Crustacea 4 general characteristics

1. Two pairs of antennae (sensory structures)

2. At least 10 walking legs

3. Molting

4. Diversity

Crustaceans generally have ___ body segments: the _________ and __________.

two; Cephalothorax, abdomen

5 Internal structures of the crayfish

1. Antenna

2. Antennule

3. Antennal gland

4. Cephalothorax

5. Abdomen

Antennae function as _______ structures

sensory

Antennae tend to have what kind of receptors? What are the responsible for?

Olfactory; responsible for smell and taste

What are antennal glands (green glands)?

Functions like a kidney; filters blood and excretes urine out of their face

Crayfish have an _____ circulatory system

open

Ecdysis

Parts of old cuticle are shed

Apolysis

Parts of old cuticle are broken down

A large portion of the crayfish exoskeleton is _______ and ______; what does this help with?

Membranous and flexible; this helps with its reabsorption when they molt

Molting sequence in lobster

1. Rupture of membrane and abdomen between the carapace

2. Part of the exoskeleton resorbed while the hardened bit on the outside is shed

3. Crayfish begins to wriggle free and absorb water, causing them to stretch and grow

4. New cuticle will begin to harden

When is an arthropod most vulnerable?

After molting

Terrestrial crustaceans

1. Isopods (pill bugs, bathynomous giganteus)

2. Brachiopoda

Large Isopod talked about in class

Bathynomous giganteus

Subphylum Hexapoda 3 general characteristics

1. 6 walking legs

2. Incredibly diverse and abundant

3. Very adaptable

Class Insecta general characteristics

1. 3 major body segments

Class Insecta 3 major body segments

Head, thorax, and abdomen

In Class Insecta, what are each of the segments responsible for?

1. Head - sensory

2. Thorax - locomotion

3. Abdomen - reproduction, digestion, respiration

Insect major sensory structures

1. Antennae (olfactory sensors)

2. Eyes (ocelli and compound eyes)

3. Mouth (chemoreception)

4. Hairs (mechanoreception)

Thorax structures

1. 6 legs

2. Wings

Abdomen structures (3 main ones)

1. Fat body (storage of nutrients)

2. Ovipositor (egg laying)

3. Spiracles (respiration)

Parasitic insects (parasitoids) are _______-specific

species

Benefits of parasitoids

1. Biocontrol method (will target specific invasive species)

What insects have muscles attached directly to their wings?

Dragonflies and Locusts

Muscles in Dragonflies and Locust wings are attached to the muscles _______.

directly

Structure of the Locust and Dragonfly wings

1. Direct flight muscles

2. Sternotergal muscles

Where are the Sternotergal, longitudinal, and direct muscles?

Where are they?

When sternotergal muscles contract, the wings are ___; when direct muscles contract, the wings are ____

up; down

When direct muscles contract, stergnotergal muscles ______

relax

What insects have muscles indirectly moving their wings?

Flies and midges

Wings in flies and midges are moved by muscles ________

indirectly

Structure of fly and midge wings (what kinds of muscles?)

1. Longitudinal muscles

2. Sternotergal muscles

When longitudinal muscles are _______ the wings are up; when the longitudinal muscles ______, the wings are down.

Relaxed; contract

In insects with indirect muscles in their wings, movement of the __________ causes their wings to move

exoskeleton

_______ muscles have faster flight in insects

indirect

Synchronous flight; what kind of musculature?

nerve impulses stimulates the flight; direct flight muscles

Asynchronous flight; what kind of musculature?

nerve impulses are periodic and trigger antagonistic muscles to contract and stimulate other muscles; usually indirect flight muscles

Insect nutrition: 3 main parts of the digestive system

1. Foregut

   • mouth to crop/gizzard); preliminary digestion

2. Midgut

   • Stomach and gastric cecae; main site for digestion and absorption of nutrients

3. Hindgut

   • Intestine (colon) and rectum; water absorption and feces formation

Most insects are:

1. Carnivores, omnivores, or herbivores?

Herbivores

Gas exchange in insects happens in the ________ system.

Tracheal

Tracheal system structure

1. Spiracles - openings to outside of body

2. Trachea

   a. Taenidia

   • Tracheoles

Gas exchange process in insects

1. Air enters through the spiracles

2. Air flows through the trachea and into the tracheoles, where O₂ diffuses into the blood/muscles

In insects, blood plays a major role in transporting ________.

nutrients

What are two ways different aquatic insects can respire?

1. Gills; trachea run through the gill flaps and diffuse O₂ from the water into the body

2. Some insects have spiracles/breathing tube, meaning they have to surface to get air (i.e. Diving beetles)

Insect compound eyes detect ____

motion