Arthropods Chapter 36-37

36.1 Phylum Arthropoda

• Largest animal phylum

• insects, spiders, shrimp, and centipedes

Characteristics

• “jointed legs”

• Have body segments w/

appendages

• high degree of cephalization

(antennae and compound eyes

Body regions- • head, thorax, and abdomen • 2 or 3 can be fused together

Skeletal Structure

• Have an exoskeleton

• Made of protein &

carbohydrate = chitin

• Sheds exoskeleton

as it grows =

molting

1) Animal splits old tight exoskeleton

2) Crawls out 3) Puffs up w/ air or

water 4) Secretes new

exoskeleton (very vulnerable)

Steps of Molting

• Body Cavity & digestive

system possess mouth &

anus

• Nervous system is similar

to annelids, but w/ larger

brains

36.2 Subphylum Crustacea

• Crabs, crayfish, lobsters, shrimp, barnacles, water fleas, & pill bugs

• Cephalothorax & abdomen

• 5 pairs of walking legs (1st pair = chelipeds)

Shrimp in the wild…

Pill bug

BARNACLE

• Jaws (mandibles) are used

for crushing food

• Force water over gills or

respire thru exoskeleton

• 1 or 2 antennae

• 5 pairs of swimmerets help in locomotion & reproduction

• Regenerate lost appendages

Telson & uropods: paddle-like tail

• Open circulatory

system

Green gland:

excretory organ

36.3 Subphylum Chelicerata &

Myriapoda

Subphylum Chelicerata

• spiders, scorpions, mites, sea

spiders, horseshoe crabs

• lack antennae

• have six pairs of appendages

Class Arachnida

• spiders, scorpions, mites, ticks

–cephalothorax

•1 pr of chelicerae

•1 pr of pedipalps

•4 prs of walking legs

–abdomen

• 8 simple eyes, chelicerae (fangs)

• spinnerets produce silk threads

• respire thru spiracles that

connect to book lungs

(tracheae)

• Malpighian tubules excrete

wastes while conserving water

Spiders

• Poisonous bite paralyzes prey

• Digestive enzymes then

liquefy organs, which are

drunk later

2 dangerous U.S. species:

Black Widow

• Red hour glass design on

abdomen

• Only females’ bite are dangerous,

extremely poisonous

• Related species: Australian

Brown Widow & Japanese Red

Widow

Brown Recluse

• Southern Spider/ house spider

• Bite causes massive cell destruction

• Related species are developing potent venom

Day 3 after a brown recluse bite…

Day 9 or 10 after brown recluse bite…

Scorpions

• have large, pincerlike pedipalps

• have stinger on the last segment

of abdomen

Mites, Ticks, & Chiggers

• Has fused cephalothorax and abdomen

• Many are parasitic, some spread diseases

• Can cause Lyme disease

(deer tick)

& Rocky Mountain

Spotted Fever

(wood or dog tick)

Subphylum Myriapoda

• Centipedes &

millipedes

Class Diplopoda

• Millipedes • rounded bodies • 2 pairs of legs

per segment

• Slow moving herbivore

• Can expel cyanide gas

Class Chilopoda

• Centipedes • have flattened

bodies • 1 pair legs per

segment

• Carnivorous & have venomous claws

• Quick moving

37.1 Class Insecta

–Head: mandibles, 1 pair of

antennae

–Thorax: 3 pairs of jointed legs,

1-2 pairs of wings

–Abdomen: 9-11 segments, no

wings or legs in adults

Comparison of Crustaceans & Insects

Circulatory, Respiratory, &

Excretory

• open circulatory system

• Gas exchange occurs by air-filled

tracheae

• Malpighian tubules remove

cellular wastes while conserving

water

Nervous System

• brain and ventral nerve cord

• sensory structures:

–simple & compound eyes

–sensory hairs

–sound-sensing tympanum

Insect Development

• They go thru metamorphosis

1) Incomplete metamorphosis: nymph hatches from egg and resembles adult – no wings

– nymph molts several times to become adult

• Grasshoppers, crickets &

lice

• 3 stages: egg, nymph,

adult

2) Complete metamorphosis:

wormlike larva (caterpillar)

hatches from egg

–molts several times before

becoming a pupa

–pupa molts to produce adult

(does not look like larva or pupa)

• Most insects

(butterflies, beetles, ants,

bees, moths & flies)

• 4 stages: Egg, Larva, Pupa

(resting), & Adult

Entomology: study of

insects and other land

arthropods

Entomologists:

scientists who study

insects

Insect

Diversity

The Success of Insects

• live in almost everywhere

–ability to fly

–exoskeleton

–small size

–short life span

–jointed appendages

37.2 Insect Behavior

Communication

-Pheromones

-Sounds

-Flashes of light

Honey Bee Behavior

Worker bees: females that do not produce young

Queen bee: only reproductive female

Drones: males that develop from unfertilized eggs

Dancing Bees

2 Types:

–round dance: food is nearby

–waggle dance: direction of food

and the distance from hive

Echinoderms &

Invertebrate Chordates

Chapter 38

38.1 Phylum Echinodermata

• “ spiny-skinned”

–Sessile or motile

–pentaradial symmetry

–endoskeleton

–water-vascular system

–tube feet

Pentaradial Symmetry

Structure

Endoskeleton of calcium

carbonate plates (ossicles)

supports and protects the

body

(1st animals w/ endoskeleton)

Water Vascular System

• Network of water filled canals

• Tube feet act like suction cups for moving & feeding

Parts:

Madreporite- opening on top

Ring canal- center circle

Radial canals- go from ring canal

into each arm/ray

Ampulla- like “bulb” of an

eyedropper

Tube feet- apply suction to a surface

• Push their stomach inside out thru

its mouth when it feeds

• NO circulatory, excretory, or

respiratory organ systems

• Nervous system- nerve ring and

radial nerve that runs along each

arm

Reproduction & Development

• Most have separate sexes

• Each arm has ovaries or testes

• External

fertilization

• Can regenerate

Class Crinoidea

• sea lilies and feather stars

Class Ophiuroidea

• “snake-tail”

• largest echinoderm class

• basket stars and brittle stars

Class Echinoidea

• “spinelike”

• sand dollars and sea urchins

Class Holothuroidea

• “water polyp”

• Sea cucumbers

Class Asteroidea

• “starlike”

• Sea stars (starfish)

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38.2 Invert. Chordates

Phylum Chordata (3 Subphyla)

–Cephalochordata

–Urochordata

–Vertebrata (vertebrates)

Subphylum Cephalochordata

• lancelets

• Retain notochord, dorsal nerve cord,

pharyngeal pouches, and postanal tail

thruout life

• feed by filtering water thru slits in

pharynx

Subphylum Urochordata

• tunicates or sea

squirts

• Most are sessile

as adults

• barrel-shaped filter

feeders

• hermaphrodites