Chapter 19: Trilobites, Chelicerates, and Myriapods

phylum arthropoda roots

arthron (joint) and podos (foot)

phylum arthropoda species count

1.1 million

what is the most diverse phylum

arthropoda

phylum arthropoda exoskeleton

chitinous, segmented

uniramous vs biramous limbs

one or two branches

mandibles or chelicerae

mouth parts

why are arthropods so diverse?

versatile exoskeleton
segmentation/appendages
respiratory system
highly developed senses
complex behaviors
metamorphosis

arthropoda diversity: versatile exoskeleton

protective yet flexible for mobility

arthropoda diversity: segmentation/appendages

efficient locomotion for division of labor

arthropoda diversity: respiratory system

tracheal system for high metabolic rate (limits body size)

arthropoda diversity: complex behaviors

social structures and symbolism

arthropoda diversity: metamorphosis

limit intraspecific competition

phylum arthropoda appendages

jointed

phylum arthropoda symmetry

bilateral with segmented body

phylum arthropoda body structure

triploblastic, reduced coelom forming hemocoel

phylum arthropoda exoskeleton

cuticular with calcium carbonate

phylum arthropoda digestive system

complete

phylum arthropoda muscular system

complex

phylum arthropoda nervous system

similar to annelids

phylum arthropoda excretory glands

coxal, antennal, maxillary, malpighian tubules

phylum arthropoda respiration

body surface (small) or tracheal system (large)

phylum arthropoda circulatory system

open

subphylum trilobita extinct for

200 years

dorsally flattened bottom dwellers and scavengers

subphylum trilobita

subphylum trilobita exoskeleton

chitinous with calcium carbonate

subphylum trilobita tagmata

head (cephalon), trunk, pygidium

antennae, compound eyes, mouth, four pairs of legs

subphylum trilobita

subphylum trilobita lack

mouthparts

giant water scorpions and horseshoe crabs are in class

merostomata

subclass eurypterida common name

giant water scorpions

subclass eurypterida current state

extinct

subclass eurypterida head

six fused segments

subclass eurypterida eyes

simple and compound

large predators with modified appendages for crushing

subclass eurypterida

subclass xiphosaurida common name

horseshoe crabs

subclass xiphosaurida current state

ancient with 4 extant

subclass xiphosaurida carapace

unsegmented, horseshoe shaped

subclass xiphosaurida long tail spike is called

telson

subclass xiphosaurida eyes

two simple on dorsal side of carapace

subclass xiphosaurida respiration

book gills

subclass xiphosaurida reproduction

high tide for thousands of mating

subclass xiphosaurida larvae resemble

trilobites

class pycnogonida common name

sea spiders

class pycnogonida species count

100

class pycnogonida habitat

shallow to deep waters

class pycnogonida body

small and thin

class pycnogonida unique feature

some segments duplicated

class pycnogonida extra legs in males

ovigers

class pycnogonida lack what systems

excretory and respiratory

class pycnogonida digestive and reproductive system

branch into legs due to limited space in body

class arachnida species count

over 80,000

what is class is among the first terrestrial arthropods

arachnida

class arachnida tagmata

cephalothorax and abdomen

class arachnida feeding

predators

class arachnida modified chelicerae

fangs

class arachnida modified pedipalps

claws

class arachnida importance

insect predators and venomous

order araneae common name

spiders

order araneae species count

40,0000+

order araneae prosoma and opisthosoma joined by

pedicel

order araneae chelicerae function

fangs, venom transfer

order araneae pedipalps function

males transfer sperm

order araneae respiration

book lungs, trachea, or both

order araneae ___ evolved independetly from insects, less efficient

tracheal system

order araneae excretion

malphighian tubules with coxal glands

order araneae eyes

eight simple

order araneae sensory

mechanoreceptors/sensory setae

order araneae silk produced by

2-3 spinnerets

order araneae silk used for

webs for prey, nests, molting

order araneae reproduction

transfer sperm via webs in pedipalps > insert in female > females lay eggs in silk nets

order araneae dangerous spiders

black widows and brown recluses

black widow species count

5

black widow venom

neurotoxic

brown recluses species count

13

brown recluses venom

hemotoxic

most ancient order of arachnids

order scorpiones

order scorpiones species count

1400

order scorpiones capture prey with

pedipalps to seize, chelicerae to shred

order scorpiones cephalothorax

short

order scorpiones eyes

one pair of big median
2-5 pairs of small lateral

order scorpiones postabdomen/metasoma

five segments with stinger at end

order scorpiones ___ serve as tactile organs

pectines

order scorpiones reproduction

mating dance > sperm on substrate > female picks up

order scorpiones development

young stays on mothers back until first molt

glows under dark light

order scorpiones

order solpugida common name

sun/camel spiders

nonvenomous, shred prey with large chelicerae

order solpugida

order solpugida habitat

desert

what order has high metabolism

solpugida

order opiliones common name

harvestmen/daddy long legs

order opiliones species count

5000

order opiliones lack

pedicel

order opiliones abdomen segmentation

external

order opiliones legs

end in claws and can regenerate

order opiliones lifestyle

carnivores and scavengers

order opiliones venom myth

not high but can bite

order acari common name

ticks and mites

most medically important arachnids

order acari

order acari species count

40,000

larges arachnids

order acari